Law A path through The Default Library ======================================== What law is for, how lawyers reason, and how the world's legal families answer the same human questions differently. Step 1. Legal Systems of the World: Same Human Problems, Different Answers -------------------------------------------------------------------------- Why: Common law, civil law, religious and customary law: where rules come from. Every society has to decide what happens when a promise is broken, someone is hurt, land is disputed, a crime is done, or power is abused. The world's legal families answer those five questions in recognisably different ways, and knowing which family you are standing in explains most of what a lawyer does there. Two friends, one in Texas and one in Mexico City, each sign a lease. Each assumes that if the landlord cheats, a court will sort it out. Both are right. But the Texan's lawyer will go looking for earlier court decisions about leases like this one, while the lawyer in Mexico City will open a code and look for the article that governs the case, and then for how the highest courts have read that article. Neither lawyer is being quirky. They were taught in different traditions. Travel a few hours further and the picture shifts again. In Berlin a student becomes a lawyer only after two state exams and two years of supervised training. In Riyadh a judge may rest a ruling on a scholarly tradition of reading the Qur'an and the Prophet's example. In Johannesburg a court applies a 1996 constitution, an English-flavoured procedure and a private law that traces back to Roman-Dutch authors. Same planet, same human troubles, different machinery. This piece is the map. It does not teach you to practise anywhere. It shows the common ground first, then the main families, then how each trains its lawyers. It describes how legal systems work; it is not legal advice, and laws differ by country and change. The course in one box Who takes itEvery law student, usually in the first year or two. In the US it is folded into other first-year courses; in much of continental Europe and Latin America it appears as an "introduction to law" or "legal history and sources" course; in England and Wales and in comparative-law programmes it is often a stand-alone course. What it is forTelling you where a rule comes from, how much weight it has and who may change it, before you read a single rule. Comes afterNothing. It is the first subject in the Law major. Leads toLegal Reasoning & Writing (35/02), Constitutional Law (35/03), Contracts & Obligations (35/04), Property (35/06), Criminal Law & Procedure (35/07), International Law & Human Rights (35/10) and European Union Law (35/11). What this piece gives youYou will not be able to say what the law is anywhere. You will be able to place a country in a family, say which sources a lawyer there would reach for first, and see why the same case is argued differently in Houston and Santiago. Easier first reads: Rights, Constitutions & the Rule of Law (18/04) and Justice: From Plato to Rawls, Nozick and Sen (05/13). The common ground: five problems every society must solve Strip away the Latin and the wigs and every legal system is answering the same five questions. Promises: when will the community force you to keep one? Harm: when must you pay for the damage you cause? Ownership: who holds a thing, and how can everyone else tell? Crime: which wrongs are the community's business, and how is guilt decided fairly? Power: what may rulers do, and who can stop them? Notice that these are human problems, not legal ones. A village of forty people has them. What law adds is a way to answer them in advance, in writing or in remembered precedent, so that strangers can rely on the answer. The families differ in where they write the answer down and who is trusted to apply it, much more than in what they want to achieve. Interactive · One problem, three answers Promise Harm Ownership Crime Power Simplified on purpose. "Latin America" means the civil-law codes of Mexico, Argentina, Brazil, Chile and Colombia, which differ among themselves; "continental Europe" means mainly France, Germany and Spain. The EU adds a layer on top (see 35/11). Read the promise row. The US asks whether something was bargained for (consideration). Chile's code, in the Bello tradition, asks for a lawful cause. France dropped "cause" as a separate requirement in its 2016 reform of the law of obligations; Germany never needed either word and leans on good faith. Four ways of drawing the line between a gift you cannot enforce and a deal you can. We return to this in Contracts & Obligations (35/04). Where rules come from: the sources of law A source of law is anything a court will accept as a reason. Every system has a stack of them: a constitution on top, then (where relevant) treaties, then statutes or codes, then regulations made under them, then court decisions, scholarship and custom. What differs is how heavily a lawyer leans on each rung. In the common-law tradition, which began in medieval England and spread to the United States, Canada, Australia, India and much of Africa, judges built large parts of the law case by case: contract, tort and property rules are still found mainly in decisions. Statutes now sit above them and can override them, but a lawyer starts by asking what courts have said. In the civil-law tradition, which grew from Roman law through the medieval universities and then the great codes, the starting point is a code or statute, and decisions illustrate how to apply it. Professors' commentaries matter more than in the US because the code is short and general. Interactive · How much does a lawyer lean on each source? US (common law) Latin America (civil) Continental Europe (civil) Mixed (e.g. South Africa) Illustrative scores from 0 (rarely cited) to 4 (the first thing a lawyer reaches for), written by the author to show a pattern, not measured. Real weights vary by field: US contract law leans on cases, but the Uniform Commercial Code is a statute. The honest picture is convergence. Common-law countries now run on statutes (tax, criminal law, consumer law, the US Constitution itself). Civil-law countries now run on precedent in practice: constitutional courts, and in Latin America the supreme courts, issue rulings that lower judges ignore at their peril. Lawyers in either family now read both kinds of source. The difference is the default, which is the thing a first-year student has to unlearn when she crosses the border. Roman law and the codes: how Europe's answer spread The civil-law family begins with Rome. In the 530s the Eastern Roman emperor Justinian had his lawyers compile centuries of Roman jurists' writings and imperial rulings into what later ages called the Corpus Juris Civilis: a Code (first issued 529, revised 534), a Digest of the jurists and a textbook, the Institutes (both 533). It was rediscovered and taught at Bologna from about 1100, and for centuries it was the shared legal language of Europe's universities. The second step was the code: a single, organised statute for a whole area of law, written for citizens as well as lawyers. France's Code civil of 1804 (the "Napoleonic Code") was the model for much of the world. Germany's Bürgerliches Gesetzbuch (BGB) entered into force on 1 January 1900 and was more abstract and technical; it influenced Japan, South Korea and others. Latin America took its own routes. Andrés Bello's Chilean Civil Code (enacted 1855, in force 1857) was adopted, with changes, by several neighbours including Colombia and Ecuador. Argentina's code by Dalmacio Vélez Sarsfield came into force in 1871 and was replaced by the new Civil and Commercial Code in 2015. Brazil's first Civil Code dates from 1916 (in force 1917) and its current one from 2002. Mexico's federal Civil Code was issued in 1928 and took effect in 1932, with each state also having its own. Interactive · Which codes exist in year ...? Year 5341804190019322016 "In force" counts from the year the code took effect, not the year it was enacted. Justinian's collection was a compilation, not a code in the modern sense. Notice what a code changes. Before 1804 a French lawyer faced hundreds of local customs plus Roman law; after it, one text. That unity was the point: one citizen, one law. It also explains the civil-law suspicion of judge-made rules. Article 5 of the French Civil Code, still in force, forbids judges from deciding cases by laying down general rules. The legislature speaks; the judge applies. Precedent: a case as a rule, or as evidence? In the common-law world a decision does two jobs: it settles the case, and its reasoning (the ratio decidendi) binds later courts below it in the same system. This is stare decisis, "stand by what has been decided". A US federal court of appeals must follow the Supreme Court; the Supreme Court is not absolutely bound by its own past, and does overrule itself. Brown v. Board of Education (1954) abandoned the "separate but equal" rule of Plessy v. Ferguson (1896) for public schools, and Dobbs v. Jackson Women's Health Organization (2022) overruled Roe v. Wade (1973). Precedent is strong, not absolute. In classic civil-law theory, a judgment binds only the parties. Prior decisions are persuasive evidence of what the code means. In practice, a line of consistent rulings from a high court (French jurisprudence constante) steers lower courts, and some countries have made that explicit. Brazil's Constitution lets the Supreme Federal Court issue súmulas vinculantes, binding summaries of settled constitutional questions, by a two-thirds vote of its ministers (a rule added in 2004). Mexico's system lets certain lines of Supreme Court rulings, called jurisprudencia, bind lower courts. The EU's Court of Justice interprets EU law for all member states, whichever family they belong to. A useful rule of thumb: in a common-law case, ask "what did the last court say about facts like mine?"; in a civil-law case, ask "what does the article say, and how have the highest courts read it?" The two questions meet in the middle more often than the textbooks admit. We practise both in Legal Reasoning & Writing (35/02). Religious, customary and mixed systems Common and civil law are the two largest families, but they are not the whole map, and they are not tidy. Three more things sit alongside them. Religious law. In Islamic law the sources are the Qur'an, the example of the Prophet (sunna) and the work of jurists (fiqh), organised in several schools of jurisprudence. Few states apply it as an uncodified whole today. Egypt's civil code of 1948, for example, was drafted on largely civil-law lines, while its constitution names the principles of Islamic law as the main source of legislation and family law draws on Islamic jurisprudence. Saudi Arabia's 1992 Basic Law names the Qur'an and the Sunna as its constitution and its courts have historically applied uncodified fiqh, though the state has recently been issuing written codes. Canon law governs the Catholic Church internally; Jewish halakha guides religious courts and, in Israel, shapes personal status law; Hindu, Muslim and other communities in India have their own personal laws for family matters. Customary law. Across Africa, the Pacific and among Indigenous peoples in the Americas, unwritten community rules about land, marriage and dispute resolution still operate alongside the state's law. Several constitutions, including South Africa's, recognise customary law, subject to the constitution's rights. It is law in the full sense: it is applied by recognised authorities and has real consequences. Mixed systems. Many places combined traditions. Scotland has civilian roots with strong common-law influence. South Africa's private law grew from Roman-Dutch authors and has English-style procedure and, since 1996, a constitution with a Constitutional Court. Louisiana's private law descends from French and Spanish civil law inside a common-law country. Quebec's Civil Code (the current one in force since 1994) governs private law while its public law follows the common-law model. Japan took French and then German codes and added American-style constitutional review after 1947. Interactive · Which family? Short labels only: every real system is a blend. Check a current source before relying on any entry. How lawyers are made: the same job, different roads You can tell a family by its classroom. In the US, law is a graduate degree: four years of any bachelor's degree, then three years for a Juris Doctor, then a state bar exam. Law school teaches by the case method, with Socratic questioning about decisions. In England and Wales you can read law at university or take any degree, and since the Solicitors Qualifying Examination began in autumn 2021 a would-be solicitor passes two exam stages and completes two years of qualifying work experience. On the continent, law is an undergraduate degree, taught from the code and the commentaries. Germany's route is the classic: about four and a half years of study (nine semesters is the standard span) and a first state exam, then two years of supervised training, then a second state exam. Spain requires a law degree, a professional master's and a state exam before one can practise as an abogado. Latin American countries typically offer a five-year degree (licenciatura or abogacía), then a professional title and registration; Brazil adds the OAB bar exam, and Chile adds a supervised practice period before the Supreme Court grants the title. Mexico requires a professional licence (cédula profesional) but has no general bar exam. Interactive · Years from starting university to practising Typical, rounded years under current rules as the author understands them. Individual routes vary by university, by year and by whether you work part-time; this is an illustration of structure, not a guide to qualifying. What a graduate just sees Before asking "what is the rule?", ask "what kind of source is it, and how much weight does it carry here?" Every system answers promise, harm, ownership, crime and power. Compare the answers, not the vocabulary. A code is a lawmaker's attempt to say it all in advance; a case is a judge saying it after the fact. Each has a failure mode: gaps for the code, inconsistency for cases. Precedent binds more in common-law courts in theory, and less than you would think in practice. High-court rulings steer civil-law judges more than the textbooks admit. Many countries are blends: South Africa, Scotland, Quebec, Louisiana, Japan, Egypt and India all are. Customary and religious law are law for the people who live under them, not a curiosity. A legal education shapes the habits of a profession: US lawyers argue from cases, German ones subsume facts under articles. Where it shows up next Legal Reasoning & Writing (35/02): how a lawyer in each family turns sources into an argument. Constitutional Law (35/03): the top rung of the stack, and the courts (American, European, Latin American) that guard it. Contracts & Obligations (35/04) and Property (35/06): where the five-problems table turns into rules. International Law & Human Rights (35/10) and European Union Law (35/11): what happens when different families must agree. In the world: every contract with a foreign party, every migration case, every multinational's compliance team, and every news story about "the court in another country". If you want to go deeper 📘 Textbook. Konrad Zweigert and Hein Kötz, Introduction to Comparative Law (Oxford, 3rd edition, translated by Tony Weir). The classic university text on legal families. 📘 Textbook. H. Patrick Glenn, Legal Traditions of the World (Oxford; check for the latest edition). Broader: includes Islamic, Hindu, Chinese and customary traditions. 📘 Gentler. John Henry Merryman and Rogelio Pérez-Perdomo, The Civil Law Tradition (Stanford University Press, 4th edition, 2018). A short book of about 190 pages for general readers and students, with Latin America included. 🌐 Free course. MIT OpenCourseWare 21H.224 Law and Society in US History (Spring 2003), a case-based look at how common law developed in one country; and 21A.219 Law and Society (Spring 2003) on law as a social institution. Both lean to the US and to anthropology; neither is a survey of the world's systems. The takeaway Every society has to answer the same five questions: promises, harm, ownership, crime and power. The families differ mostly in where the answer is written (cases or codes) and who is trusted to apply it. Most real systems blend, and a lawyer's first skill is knowing which source carries the weight where she is standing. Try this: pick a country you care about and look up whether it is common law, civil law or mixed. Then find one thing a court there decided in the last year and ask whether the judges quoted earlier cases, an article of a code, or both. Sources & Further Reading Sources. Legal families, Justinian's compilations (Code 529, revised 534; Digest and Institutes 533), the French Code civil (1804) and its article 5, the BGB (in force 1 January 1900), Bello's Chilean code and its adoption elsewhere, Vélez Sarsfield's Argentine code, Brazil's codes of 1916 and 2002, Mexico's Federal Civil Code (1928, in force 1932) and Louisiana, Quebec, Scotland and South Africa as mixed systems: Merryman and Pérez-Perdomo, The Civil Law Tradition; Zweigert and Kötz; Wikipedia's "Civil law (legal system)" as a cross-check. Brazil's Constitution, art. 103-A (binding summaries, two-thirds of the Supreme Federal Court's members, added by Amendment 45 of 2004). SQE: Solicitors Regulation Authority and Wikipedia ("Solicitors Qualifying Examination": in effect from autumn 2021; two years' qualifying work experience). Court dates: Brown 1954, Plessy 1896, Dobbs 2022, Roe 1973. Education routes are summarised from national rules and are approximate. This piece describes how legal systems work and is not legal advice. 📘 Merryman & Pérez-Perdomo, The Civil Law Tradition 📘 Zweigert & Kötz, Introduction to Comparative Law 🌐 MIT OCW 21H.224 Law and Society in US History Step 2. Legal Reasoning & Writing: From a Rule and Some Facts to an Answer -------------------------------------------------------------------------- Why: How lawyers read a case or a code and build an argument. Lawyers do not look up the answer. They build it: find the rule, state the facts, say what the words mean, and show why this case is like or unlike another. The tools differ between a US law school and a German state exam, but the skeleton is the same. A park has a sign: No vehicles in the park. A man pushes his bicycle along the path. A child drives a battery-powered toy car. An ambulance cuts across the lawn to reach someone who has collapsed. A town has mounted an old army truck on a plinth as a war memorial. Which of these break the rule? Most people answer fast, and most answers differ. That gap, between a rule everyone understands and a case nobody is sure about, is where legal reasoning lives. A lawyer does not guess. She asks what the rule is for, what its words ordinarily mean, what its authors had in mind, and what courts have done with similar things. Then she writes it up so that a stranger can check every step. This piece describes how that works across the main traditions. It is about method, not about any country's current law, and it is not legal advice; laws differ by country and change. The course in one box Who takes itEvery law student in year 1. In the US it is the legal research and writing course taught alongside doctrinal classes; in Spain, Mexico, Argentina and Chile it appears in introductory courses and in the "practical case" exercises (casos prácticos); in Germany it is learned in every exam-style case solution; in France through the dissertation and the commentaire d'arrêt. What it is forTurning a rule and a messy set of facts into an argued, checkable conclusion. Comes afterLegal Systems of the World (35/01). Leads toCriminal Law & Procedure (35/07), Civil Procedure & Evidence (35/08), and every doctrinal subject, from Contracts & Obligations (35/04) to Administrative Law (35/09). What this piece gives youYou will not learn to win a case. You will be able to read a judgment or a code article without getting lost, tell a holding from an aside, and see why the same facts are written up differently in Boston and in Berlin. Easier first read: How a Law Gets Made (18/07). The legal syllogism: a rule, some facts, a conclusion The oldest picture of legal reasoning is a syllogism. The major premise is a rule ("whoever, by fault, causes damage to another must repair it"). The minor premise is a finding about the facts ("Ben, by negligence, caused Chen's broken wrist"). The conclusion follows ("Ben must repair it"). Continental lawyers call this subsumption: placing the facts under the rule. Common-law lawyers do the same thing but find the rule in cases. Real law is rarely that tidy, because both premises are contested. Is the rule really what you say? Did the facts really happen that way, and do they fit the words? Most of a lawyer's work is on the premises, not the logic. A good way to see this is to break the rule into elements: the conditions that must all be present for the consequence to follow. Miss one and the rule does not apply. Interactive · Elements checklist France: Civil Code art. 1240 Germany: BGB section 823(1) Facts (invented): Ben left a ladder across a footpath at night. Chen tripped and broke a wrist. Tick what you think is proven; untick what the other side would dispute. A teaching device, not a prediction: real courts also look at defences, shared fault and the extent of damage, and other regimes (strict liability, insurance) may apply. The French text is one sentence. In the author's own English translation: any act of a person that causes damage to another obliges the person by whose fault it occurred to repair it. This is article 1240 of the Code civil; until the 2016 reform it was article 1382, so older books and judgments cite the old number. Four elements hide inside the sentence: an act, damage, fault and a causal link ("that causes"). The German code takes the opposite approach. Section 823(1) of the BGB lists the protected interests (life, body, health, freedom, property and "another right"), and requires wrongfulness and fault. Notice what the list leaves out: a pure financial loss is not on it. That is a rule you learn only by reading the article closely, which is the skill. Reading a code article therefore means three things. Find the facts that trigger it (the elements). Find the consequence (repair, nullity, a penalty). And check its neighbours: the exceptions, the definitions elsewhere in the code, and the heading under which it sits, because where an article is placed tells you what family of rule it belongs to. Reading a case: facts, issue, holding, reasoning A judgment is not a story and not a rule. It is a decision with its reasons attached, and a student's first job is to take it apart. Common-law casebooks teach five parts: the facts (what happened and how the case got to court), the issue (the legal question), the holding (the answer needed to decide this case), the reasoning (why), and obiter dicta, remarks "by the way" that were not needed for the result. The holding with its reasoning is the ratio decidendi, the part later courts treat as binding. Obiter may be persuasive but it is not the rule. Civil-law judgments have their own anatomy. A Spanish judgment is divided into antecedentes de hecho (facts and procedure), fundamentos de derecho (the legal grounds) and the fallo (the ruling). A German judgment separates the Tatbestand (the facts) from the Entscheidungsgründe (the reasons). French supreme-court judgments have been famously terse, traditionally one long sentence of reasoning, and the court has been moving toward fuller explanations in recent years. French students summarise a ruling on a fiche d'arrêt: facts, procedure, the parties' claims, the problème de droit and the court's solution. The labels differ; the work is the same. Interactive · Take a judgment apart An invented, simplified decision. Decide what each sentence is doing. Facts Issue Holding Reasoning Obiter Next sentenceStart again Illustrative text written for this piece; it is not a real case. Interpretation: what the words mean when the words run out Words never apply themselves. The philosopher H. L. A. Hart, in a 1958 article in the Harvard Law Review, used a "no vehicles in the park" rule to make the point: some cases fall in the clear core (a car) and others in a penumbra of doubt (a bicycle, a toy car). Lon Fuller replied in the same journal that you cannot decide the penumbra without asking what the rule is for, and offered the example of a truck mounted on a pedestal as a war memorial. The disagreement is still live: how far does a judge go beyond the dictionary? Over two centuries lawyers have named the main tools. Friedrich Carl von Savigny, writing in 1840, described four "elements" of interpretation: the grammatical, logical, historical and systematic. Spain's Civil Code puts them in a single sentence. Article 3.1 says (in the author's translation) that rules are to be interpreted according to the proper meaning of their words, in relation to their context, their historical and legislative background and the social reality of the time they are applied, attending fundamentally to their spirit and purpose. US debates use different names: textualists stress the ordinary meaning of the text, purposivists the problem the law was meant to solve, intentionalists what the drafters wanted, and some constitutional scholars argue for reading broad provisions in light of changing circumstances. Interactive · Who breaks the rule? Three readings Assumptions (invented): the rule's purpose is a safe, quiet park for people on foot; its drafters, in 1952, were responding to motor cars damaging the lawns. Different assumptions give different answers, which is the point. When the three readings agree you are in the core, and there is not much to argue. When they split you are in the penumbra, and the argument is the job. Note that none of the methods is "the" correct one. A judge's choice among them is itself something a good lawyer expects to defend. Analogy: the same facts in two traditions When no rule fits exactly, lawyers reason by analogy: this case is like that one in the ways that matter, so it should be decided alike. In common-law reasoning the "that one" is an earlier decision, and the argument is about which facts were essential. A judge can also distinguish an earlier case by showing that a fact that mattered is missing here. Edward Levi's classic An Introduction to Legal Reasoning (1949) describes this as reasoning from case to case. In the civil-law tradition the analogy is to a provision. Spain's Civil Code, article 4.1, says (author's translation) that analogy applies when a rule does not cover a specific situation but governs a similar one in which there is "identity of reason". Same logic, different anchor. Watch the two traditions handle the same facts. A famous common-law case, Donoghue v Stevenson [1932] AC 562, was decided by the House of Lords on 26 May 1932 by three votes to two. A woman drank ginger beer from an opaque bottle bought by a friend and, she said, found a decomposed snail in it. She had no contract with the manufacturer. Step through how each kind of lawyer would approach a modern version. Interactive · One bottle, two lawyers Common-law lawyer Civil-law lawyer Next stepReset Simplified. Product-liability statutes (in the EU, following a 1985 directive) now answer the snail question directly in many countries; the exercise shows the method, not the modern result. IRAC and its cousins: writing the argument down American law students learn a formula for answering an exam question or a memo: IRAC, for Issue, Rule, Application, Conclusion. State the question; state the governing rule, with its source; apply the rule to the facts, taking each element in turn and noticing the weak points; conclude. Variants exist (CREAC puts the conclusion first and last), and practitioners usually put the bottom line up front, because a busy reader wants the answer before the proof. Germany's equivalent is the Gutachtenstil ("opinion style"), the only way a state-exam case is acceptable. It has four moves: the Obersatz (a question put in the conditional: "A could claim damages under section 823(1)"), the Definition of each element, the Subsumtion (fitting the facts to the definition), and the Ergebnis (the result, now in the indicative). The conclusion comes last on purpose: it shows the reader that nothing was assumed. In judgments the order reverses (Urteilsstil: result first). French students write a plan en deux parties, two main parts each with two sub-parts, and in the commentaire d'arrêt they identify the legal problem before the solution. Spanish and Latin American students facing a caso práctico write the facts, the applicable articles and doctrine, and the conclusion. Interactive · Put the argument in order IRAC (US) Gutachtenstil (Germany) Tap the four sentences in the order a reader should meet them. Shuffle and restart Writing: bottom line first, plain words Legal writing has a reputation for Latin and long sentences, and for generations lawyers defended both as precision. The plain-language movement, in the US, the UK and elsewhere, argues the opposite: a sentence a client cannot follow does not make the law clearer, and ambiguity usually hides in the long ones. Bryan Garner's Legal Writing in Plain English is the standard American primer. The habits are simple: say the answer first; one point per paragraph; define a term once and keep it fixed; cite the source for each rule; and put the facts that hurt your side in plainly, because the other side will. What the traditions share is checkability. A good legal text lets a hostile reader see every step: this is the rule and here is where it comes from; these are the facts and here is the evidence; this is how I get from one to the other. That is the nearest thing law has to a proof. What a graduate just sees Every legal answer is a rule plus facts. Most arguments are about one of the two premises, rarely the logic. A rule is a list of elements. If one is missing, the rule does not bite, so the first question is "which element is in doubt?". A case has a holding and everything else. Only the holding, with its reasons, is the part that binds. A word has a core and a penumbra. In the penumbra, arguments about purpose, history and text compete, and none wins automatically. Analogy is the universal tool: decide the new case like the old one if the important facts match. The dispute is always about which facts are important. Different traditions write the same reasoning in different orders, but they all require the reader to see the rule, the facts and the steps between. Plain words and the answer first are not a lack of rigour. They make rigour visible. Where it shows up next Contracts & Obligations (35/04): offer, acceptance and cause are elements; most contract disputes are about whether one is present. Criminal Law & Procedure (35/07): every crime is a list of elements plus a mental state, and the prosecution must prove each. Constitutional Law (35/03): the hardest interpretation fights, because the texts are short and broad. Civil Procedure & Evidence (35/08): how the "facts" premise gets established. In the world: every legal memo, every judgment you read in the news, every terms-and-conditions clause you wonder about. If you want to go deeper 📘 Textbook. Edward H. Levi, An Introduction to Legal Reasoning (University of Chicago Press, 1949). Short and still assigned; the classic account of reasoning by example. 📘 Textbook. Glanville Williams, Learning the Law (Sweet & Maxwell; use the latest edition). Written for English first-year students; a plain guide to cases, statutes and essays. 📘 Gentler. Karl Llewellyn, The Bramble Bush (1930; reissued by Oxford University Press). Lectures to first-year law students on what courts do. 📘 Writing. Bryan A. Garner, Legal Writing in Plain English (University of Chicago Press, 2nd edition). 🌐 Free course. MIT OpenCourseWare 24.235J Philosophy of Law (Spring 2012), including the Hart and Fuller debate; and 17.245 Constitutional Law (Spring 2013) for real cases to practise on. The takeaway Legal reasoning is a rule, some facts and a chain of steps that a stranger can check. Break the rule into elements, read cases for their holdings, argue the borderline by text, purpose and history, reason by analogy, and write the answer down in a form the reader can test. Try this: take any sign or terms-and-conditions clause you meet this week. Write the rule in one sentence, list its elements, and find one real situation in its penumbra. Then say which reading you would defend and why. Sources & Further Reading Sources. Code civil art. 1240 (formerly art. 1382, renumbered by the ordonnance of 10 February 2016, in force 1 October 2016): official text via Légifrance and the French reform documentation. BGB section 823(1): the Federal Ministry of Justice's English translation. Spanish Código Civil arts. 3.1 and 4.1: the consolidated text on the BOE website. Hart, "Positivism and the Separation of Law and Morals", 71 Harvard Law Review 593 (1958); Fuller's reply, 71 Harvard Law Review 630 (1958). Savigny, System des heutigen römischen Rechts (1840). Donoghue v Stevenson [1932] AC 562 (House of Lords, 26 May 1932, 3 to 2). Court-judgment structures (antecedentes/fundamentos/fallo; Tatbestand/Entscheidungsgründe; the French fiche d'arrêt) are standard teaching formats. The park scenario, ladder facts and mini judgment are invented for teaching. English renderings of the code articles are the author's own. This piece describes legal method and is not legal advice. 📘 Levi, An Introduction to Legal Reasoning 📘 Llewellyn, The Bramble Bush 🌐 MIT OCW 24.235J Philosophy of Law Step 3. Contracts & Obligations: What Makes a Promise Bind ---------------------------------------------------------- Why: Promises the law will enforce, and what happens when they're broken. Every society must decide which promises it will back with force. The answers differ by family, but the five questions behind them do not. You tapped "I agree" on a ride-hailing app this morning, or bought a train ticket, or let a landlord keep a deposit in exchange for a key. Nobody shook a hand and nobody signed in ink, yet each of those was a promise that a court somewhere would, in the right circumstances, force someone to keep. Most of the time nobody ever thinks about this. The contract works because everybody knows it could be enforced. Every society has had to answer the same question: which promises does the community back with force, and what happens when one is broken? Too few enforceable promises and nobody can trade with a stranger. Too many and people are trapped by every careless word. The law of contracts, which many civil-law countries file under the wider heading of obligations, is the long answer. It is also the subject where the world's legal families sound most different while arriving, most of the time, at the same place. This describes how legal systems work. It isn't legal advice; laws differ by country and change. The course in one box Who takes itEvery law student. In the US it is a first-year course (the "1L" core). In the five-year law degrees of Spain, Mexico, Argentina and Chile it sits among the first private-law courses as "obligations and contracts"; in Germany it is part of the law of obligations (Schuldrecht) that every state-exam candidate must master. Business and economics programmes teach a lighter version. What it is forTelling a binding promise from a mere statement, and working out what the loser of a broken promise gets. Comes afterLegal Systems of the World (35/01). Leads toTorts & Civil Liability (35/05), which borrows its idea of "obligation"; Property (35/06), because ownership is mostly transferred by contract; and Civil Procedure & Evidence (35/08), where contracts get enforced. What this piece gives youYou will not be able to draft a contract or say whether yours is valid. You will see why a promise to give a gift is treated so differently from a promise to sell, why "good faith" means different things on either side of the Atlantic, and why a court will usually award money rather than make a seller hand over the goods. Easier first reads: Rights, Constitutions & the Rule of Law (18/04) and Justice: From Plato to Rawls, Nozick and Sen (05/13). Everyday background: The Legal Bare Minimum (04/04). The common ground, and where the families part Strip away the vocabulary and every legal system asks five questions about a promise. Did the parties really agree? Was the agreement the kind the law will enforce, or only a social arrangement? Was the agreement fairly reached, with free and informed consent? How much honesty do the parties owe each other on the way in and while performing? And if it is broken, what does the injured side get? The table shows how three big families answer. Remember that "United States" and "England and Wales" share the common-law tradition (the US inherited it) but have diverged in details, and that Latin America, Spain and much of Europe descend from the Roman-law codes, with France's 1804 Code civil and Germany's BGB (in force 1900) as the two great models. QuestionUS and EnglandLatin AmericaFrance and Germany Where the rules liveJudges' decisions, plus statutes such as the US Uniform Commercial Code (UCC) for sales of goodsNational civil and commercial codes (Mexico, Argentina 2015, Brazil 2002, Chile 1855, Colombia)The codes: France's Code civil (contract law rewritten 2016), Germany's BGB Why a promise bindsA bargain: something given or promised in return (consideration)Consent, an object, and in many codes a lawful causa (the reason for the promise)Consent and lawful content; France dropped the separate cause in 2016 Good faithRequired in performance in the US; England resists a general dutyA general principle in the codes, explicit in Argentina's 2015 codeA central principle (France art. 1104; Germany BGB §242) Default remedyMoney damagesChoice of enforcement or termination, with damagesEnforcement in kind is available; Germany treats it as the primary right At world level, cross-border sales between businesses are harmonised by the UN Convention on Contracts for the International Sale of Goods (CISG, concluded in Vienna in 1980 and in force since 1988). Its parties include the US, China, Germany, France, Mexico, Argentina and Chile (not the UK), and it applies to a sale between businesses in two of them unless the contract opts out. It is a useful neutral reference below: its authors were deliberately blending the families. Offer and acceptance: when does the deal exist? Most contracts are formed by an offer (a proposal the other side can accept to create a deal) and an acceptance. When both people are in the same room there's no puzzle. The puzzle appears at a distance. If you post an acceptance and the offeror posts a withdrawal the same day, which wins? In the 1818 English case Adams v Lindsell a wool dealer's acceptance was held to bind him when posted, even though it arrived late: the "mailbox rule". The common law (US and England) keeps it to this day: the acceptance takes effect when sent, but the withdrawal of an offer takes effect only when it arrives. The civil-law tradition and the CISG lean to receipt: a message counts when it reaches the other side. Germany goes a step further: under BGB §145, a person who makes an offer is bound by it unless they expressly excluded the binding effect, so a withdrawal doesn't free them. Under CISG art. 16, an offer can be revoked only if the revocation reaches the other side before they send their acceptance, and not at all if the offer says it stays open for a fixed time. Play with the clock. Post takes two days each way, and the offer was posted on day 0, so the earliest an acceptance can go out is day 2. Interactive · The post race Acceptance posted on day Withdrawal of the offer posted on day Acceptance arrives Acceptance is lost in the post Offer is silent Offer says "open until day 10" Illustrative simplification: a message counts on its day, and a tie between a withdrawal's arrival and an acceptance's posting is treated as the withdrawal arriving first. Real courts look at hours and facts. In common law an unpaid "open until" promise is normally still revocable (a signed merchant's offer to sell goods under the UCC is an exception). With the starting settings (acceptance posted day 3, withdrawal posted day 2, arriving on day 4), all three rules say there is a contract: the acceptance was sent before the withdrawal arrived. Move the acceptance to day 5 and the paths split: the common law and the CISG say the withdrawal got there first, so there is no deal, while Germany's binding offer means the deal still exists. Now lose the letter: the common law still finds a contract (the English Household Fire v Grant, 1879, held that a lost acceptance still bound the offeror), while a receipt rule does not. Both approaches are defensible; each puts the risk of the post on someone different. Consideration, causa and form: which promises count? Not every agreement is a contract. If you promise your aunt a lift to the airport and forget, nobody expects a court. The law needs a filter, and here the families use different filters. The common law demands consideration: each side must give or promise something in return, a "bargained-for exchange". The classic statement is Currie v Misa (1875): a benefit to one side or a detriment to the other. Notably, the law doesn't ask whether the exchange is fair. A car for one pound is still a bargain, although other doctrines (fraud, duress, unconscionability) may be available. The civil-law filter is different. Chile's 1855 Código Civil (art. 1445), like those that followed it, lists consent, capacity, a lawful object and a lawful causa as conditions of validity. Causa is the reason a person undertook the obligation. France had the same idea in the old art. 1108 until the 2016 reform replaced it with a requirement of lawful and certain content (new art. 1128); the old worries about a contract with no purpose are now handled by other rules, such as one that voids a derisory counter-performance. Germany never used causa for contracts: its filters are consent, then form and morality (§138 voids contracts contrary to good morals). The bigger difference is the promise to give for nothing. Because there is no exchange, the common law won't enforce a plain gift promise. The civil-law world won't either, but for a different reason: gifts are a special act that needs form. Germany's BGB §518 requires a notary for a promise to give, which cures itself once the gift is performed. French law requires a notarial deed for most gifts. Which promises count? Try the scenarios. Interactive · Is there a binding contract? Simplified and illustrative; not a tool to decide your rights. "Latin America" here means the Bello-style codes (Chile, Colombia) and Argentina's 2015 code, which keep causa; Mexico's federal code lists consent and an object, and details vary by country and state. Notice what comes out. For ordinary commercial bargains all families agree. They differ at the edges: gifts, grossly lopsided prices, and promises that someone relied on. The US has a special doctrine for that last case, promissory estoppel (Restatement (Second) of Contracts §90), under which a promise that the promisor should expect to induce reliance, and does, can be enforced to the extent justice requires. It was invented to patch the hole that the consideration rule leaves. Good faith: how much must you care about the other side? Does a negotiator who walks away at the last minute owe anything? This is the sharpest transatlantic contrast. The English House of Lords held in Walford v Miles (1992) that a promise to negotiate in good faith is unenforceable, because negotiators are allowed to pursue their own interests. The US imposes a duty of good faith in performing a contract (UCC §1-304, Restatement (Second) of Contracts §205), but generally leaves parties free to leave talks, with the exception that reliance can matter: in Hoffman v Red Owl Stores (Wisconsin, 1965), a would-be franchisee who sold his bakery on the franchisor's assurances recovered his losses. Continental systems start from the opposite end. Germany's BGB §242 requires performance as Treu und Glauben (good faith) and custom demand; since the 2002 reform, §311(2) makes pre-contract negotiations a relationship with duties of care, following Rudolf von Jhering's 1861 doctrine of culpa in contrahendo (fault in forming a contract). France's art. 1104 makes good faith a public-order rule for negotiation, formation and performance. Predict first, then check. Interactive · Walking away from the table Two firms negotiate for months. The day before signing, one walks away with no reason. The other has already spent money gearing up. Can it recover that spending? Yes, in every country Depends on the legal family No, never Pick a prediction to see how the systems answer. Mistake and duress: when "yes" isn't really yes A contract is the meeting of two wills, so what if one will was defective? Two kinds of defect run through every system. Mistake: one or both sides were wrong about something fundamental. The English chestnut is Raffles v Wichelhaus (1864): cotton was sold "to arrive ex Peerless from Bombay", but there were two ships called Peerless, sailing months apart, and each side meant a different one. The court would not enforce a deal in which the parties had never meant the same thing. Duress: one side was forced, by threats or by exploiting a desperate situation. The families file these under different names. The French code speaks of vices du consentement (defects of consent): erreur (error), dol (deceit) and violence, and the 2016 reform added abuse of a state of dependence. Germany lets a person avoid ("anfechten") a declaration made under a mistake (§119) or induced by deceit or unlawful threats (§123). The common law uses mistake, misrepresentation, duress and undue influence, each with its own tests. A subtle case shows how the legal families approach "pressure". A builder, halfway through a job, demands more money and the owner, who has no time to find another, agrees. In Alaska Packers' Association v Domenico (US, 1902) sailors who refused to work unless their wage was raised were held to have given no consideration for the raise, since they were already bound. The English Court of Appeal in Williams v Roffey Bros (1989) found that a practical benefit to the promisor can count, as long as there was no duress. The point for a beginner: the question is never just "did they say yes?" but "was the yes free, and was it given for something?" Remedies: damages or the thing itself? Finally, the loser of a broken promise needs something. The default in the common law is expectation damages: money to put you where you would have been had the promise been kept. The limit comes from Hadley v Baxendale (1854): a mill-owner whose crankshaft was delayed in transit could not recover profits the carrier hadn't been told about; damages cover losses that were foreseeable at the time of the contract. A court will order specific performance (do what you promised) only if money is inadequate, as for land or unique objects. Civil law starts at the other end. A creditor has a right to the performance itself: the German BGB (§241) states that the creditor may demand it, and the French reform of 2016 lists enforcement in kind first, with limits for impossibility or manifest disproportion. The CISG compromise (art. 28) tells a court it need not order specific performance if its own law wouldn't. In practice, with ordinary goods, all systems end up with money. The common law's money-first approach has a famous defender. Oliver Wendell Holmes wrote in 1897 that the duty to keep a contract at common law "means a prediction that you must pay damages if you do not keep it". Law-and-economics scholars turned this into efficient breach: if a third party values the goods more than your buyer does, the best outcome for everyone is to breach and pay the buyer's loss. Critics, such as the legal philosopher Seana Shiffrin, reply that a promise is a moral commitment and that treating it as an option to pay misdescribes what promising is. The simulation below uses the arithmetic; the argument over its morality is still open. Interactive · What does a broken promise cost? A seller promised a machine to a buyer. All amounts are illustrative units. Agreed price (P) Value of the machine to the buyer (V) Price of a replacement elsewhere (M) A third party offers the seller (T) Stylised: the seller's cost is the same either way, the third party really values the machine at T, and the buyer can cover at M. In reality, "foreseeability" limits, litigation costs and the buyer's own mitigation change the numbers. With the starting numbers (price 200, buyer values it at 300, replacements cost 300, third party offers 350), the buyer's expectation damages are 100, the seller's gain from selling to the third party is 150, so the seller pays 100 and keeps 50 more than performing would have given. Under a specific-performance regime the seller would have to negotiate a release with the buyer, who would want at least 100: a deal is still possible because the third party values it at 350 > 300. The two regimes end in the same place, with a different split of the surplus. That is the "Coase" insight: when bargaining is cheap, the remedy changes who gets the money more than who ends up with the machine. What a graduate just sees Every deal has a moment when it starts to exist; ask which rule fixes that moment, and who carries the risk of the post. A contract is a filter on promises. The common law filters by bargain (consideration), the codes by consent, content and sometimes causa, and every system filters gifts by form. "Good faith" is not one thing: honest performance (US), fair dealing in negotiation (Germany, France), or almost nothing (English negotiators). A "yes" must be free and informed; pressure, deceit and shared mistakes undo it. Damages aim at the position you would have been in had the promise been kept, not at punishing the breaker. Money is the common remedy in every system; the question is whether the court begins with the thing or with the price. When a legal rule looks arbitrary, ask who the rule makes bear the risk. Where it shows up next Torts & Civil Liability (35/05): when a duty comes from the law and not from a promise, the same questions (fault, causation, remedy) come back in a different guise. Property (35/06): buying a flat is a contract, but the ownership it transfers needs the land registry. European Union Law (35/11): consumer rules, such as the 14-day withdrawal right for distance purchases, override ordinary contract doctrine in the name of fairness. The real world: the terms you click through, the lease you sign, the freelance invoice you chase, and every international sale of goods under the CISG. If you want to go deeper 📘 Textbook. Ewan McKendrick, Contract Law: Text, Cases, and Materials (Oxford University Press). A standard English course text. 📘 Textbook, comparative. Hein Kötz, European Contract Law (Oxford University Press, 2nd ed., 2017, translated by Gill Mertens). Compares common-law and continental answers question by question and covers the 2016 French reform. 📘 Gentler. Charles Fried, Contract as Promise: A Theory of Contractual Obligation (Oxford University Press, 2nd ed.). A short, readable argument that contract law is the law of keeping promises, the view Shiffrin and others defend and law-and-economics scholars contest. 🌐 Free course. Contract Law: From Trust to Promise to Contract (HarvardX, Charles Fried and Daniel Markovits), listed on Harvard Online and edX. Free to audit when a session is open; check the page for current availability. The takeaway Every legal system backs some promises with force and not others. Most of the time they agree; they diverge at the edges, in when a deal starts, whether a gift can bind, how much good faith is owed before signing, and whether the court starts with the thing or the price. Learn the five questions (agreement, enforceability, free consent, good faith, remedy) and you can read any country's contract law. Try this: this week, pick one agreement you made (a subscription, a lease, a favour traded). Ask when it began to exist, what you each gave in return, and what you would get if the other side broke it. Sources & Further Reading Sources. Cases: Adams v Lindsell (1818) 1 B & Ald 681; Household Fire v Grant (1879) 4 Ex D 216; Currie v Misa (1875) LR 10 Ex 153; Raffles v Wichelhaus (1864) 2 H & C 906; Hadley v Baxendale (1854) 9 Exch 341; Walford v Miles [1992] 2 AC 128; Hoffman v Red Owl Stores 26 Wis 2d 683 (1965); Alaska Packers' Ass'n v Domenico 117 F 99 (9th Cir 1902); Williams v Roffey Bros [1991] 1 QB 1. Statutes: BGB §§119, 123, 145, 130, 138, 241, 242, 311, 518 (gesetze-im-internet.de); French Code civil arts. 1104 and 1128 as renumbered by ordonnance no. 2016-131 of 10 February 2016, in force 1 October 2016 (ratified by loi no. 2018-287); Chile Código Civil art. 1445; CISG arts. 16, 18 and 28 (UNCITRAL text); US UCC §1-304 and Restatement (Second) of Contracts §§71, 90, 205. Holmes, "The Path of the Law", Harvard Law Review 10 (1897). Numbers in the interactives were computed in node and checked by hand. This is a description of how legal systems work, not legal advice. 📘 McKendrick, Contract Law 📘 Kötz, European Contract Law 📘 Fried, Contract as Promise 🌐 UNCITRAL: the CISG text 🌐 The BGB in English translation Step 4. Torts & Civil Liability: Who Pays When Someone Is Hurt -------------------------------------------------------------- Why: Who pays when someone is hurt. Every accident forces a choice about who absorbs the loss. Tort law is the machinery for choosing, and the legal families built it very differently. In 1928 a woman waiting on a platform of the Long Island Rail Road was struck by a set of scales that fell over after a distant explosion. Helen Palsgraf had done nothing wrong, and the railway guard who had helped a passenger onto a train, dislodging a package of fireworks, had never seen her. She sued anyway. Judges in New York spent pages deciding whether the guard owed her anything. A century later, law students on four continents still study the case, because it asks the question every injury raises: it happened, it hurt, and someone has to bear the cost. Who? A law graduate looks at a banana skin, a faulty phone charger or a pothole and sees the same machine: a duty, a breach, a link from act to harm, and a sum of money meant to put things right. This is the law of torts in the common-law world and of civil liability (responsabilidad civil, responsabilité civile) in the civil-law world. The names differ and the problem is shared. This describes how legal systems work. It isn't legal advice; laws differ by country and change. The course in one box Who takes itEvery law student: in the US a first-year course (Torts), in Spain and Latin America part of obligations and civil liability, in Germany the law of "unlawful acts" (Deliktsrecht). Insurance, medicine and engineering programmes teach a short version. What it is forDeciding when a harm that no one promised to prevent must be paid for by whoever caused it, and how much. Comes afterContracts & Obligations (35/04), whose idea of an "obligation" it borrows. Leads toCriminal Law & Procedure (35/07), which shares the question of fault; Civil Procedure & Evidence (35/08), where claims are proved; and Administrative Law (35/09), where the state is the defendant. What this piece gives youYou won't be able to tell whether you have a claim. You will see why "careless" can be priced, why a court can say you were a cause and still not liable, and why a hospital burn in Texas and one in Lyon end in very different cheques. Easier first reads: Rights, Constitutions & the Rule of Law (18/04) and Justice: From Plato to Rawls, Nozick and Sen (05/13). The common ground: harm needs a payer Accidents are not rare. Cars collide, drugs have side-effects, ladders slip. Each society must decide who absorbs the loss: the victim (where it falls), the injurer (who may have been careless), an insurer or the public (through a fund). Tort law is the system that picks the injurer when two things are true: the injurer is in some sense responsible, and the law has a rule that makes the cost move. Its two jobs are compensation (repair the loss) and deterrence (make carelessness expensive). Some places have decided the lawsuit is the wrong tool. New Zealand's Accident Compensation scheme, in force since 1974, mostly replaced suing for personal injury with a no-fault public fund. QuestionUS and EnglandLatin AmericaFrance and Germany Starting pointSeparate torts and duties, built case by caseA general clause: whoever unlawfully harms another must repair itFrance: one general clause. Germany: a list of protected interests Main testNegligence: did the defendant fall below a reasonable standard?Fault, plus strict liability for risky things and consumer productsFault, plus strict liability for products under EU law Who decides damagesOften a jury, in the USJudges, with growing guidelines for non-economic harmJudges, with scales and guidelines Punishing the wrongdoerPunitive damages in the US; limited in EnglandRare; Argentina's consumer law has a punitive damageGenerally not available Duty of care or one big clause: how the families begin The common law grew up with separate wrongs: assault, trespass, nuisance and later negligence. The great step came in Donoghue v Stevenson ([1932] AC 562, House of Lords), where a woman who drank ginger beer from an opaque bottle and found the remains of a snail was allowed to sue the manufacturer, although she had no contract with him. Lord Atkin's answer was the "neighbour" principle: you must take reasonable care to avoid acts you can reasonably foresee would injure the people so closely affected that you ought to have them in mind. Courts later found that foreseeability alone would make liability limitless, so England now asks (Caparo v Dickman, 1990) about foreseeability, proximity and whether it is fair, just and reasonable to impose a duty. In America, Judge Cardozo's majority in Palsgraf (1928) said that a duty runs only to those within the foreseeable zone of danger. The guard owed her nothing. The civil-law codes begin with a sentence. France's old art. 1382, now art. 1240 after the 2016 renumbering, says that any act of a person that causes harm to another obliges the person by whose fault it happened to repair it. Mexico's Federal Civil Code art. 1910 says that anyone who acts unlawfully or against good customs and causes harm must repair it. Germany does not have so wide a clause. BGB §823(1) names the interests protected (life, body, health, liberty, property and "another right"), so a purely financial loss with no injury to one of them is not covered by it, and §276(2) defines negligence as ignoring the care required in dealings. The two methods meet in the middle more than their labels suggest. Where French law has one broad sentence, courts build a case law of exceptions to it. Where the common law has duties, judges stretch them. One real difference remains: the code's sentence tells a judge the default is liability for fault, whereas the common-law judge must find a duty first. Both approaches give the same result in a road accident and diverge on things like pure economic loss and harm from omissions. Negligence and the Hand formula: when is skimping careless? Fault must be judged against something. The common law uses the reasonable person; French law, until a 2014 reform, spoke of the bon père de famille (good father of the family), and now of a reasonable person. But what is reasonable? In United States v Carroll Towing Co. (2d Cir. 1947), a barge broke loose in New York harbour when its attendant was ashore. Judge Learned Hand wrote a rule of thumb: liability depends on whether B, the burden of precaution, is less than P × L, the probability of the harm times its gravity. B < P × Lcost of the precaution < chance of the accident × size of the loss, and you are negligent if you skipped it A worked number. A guard rail costs $100. Without it there is a 1% chance a year that someone falls, and a fall costs $50,000. P × L is 0.01 × 50,000 = $500. Because $100 < $500, skipping the rail is negligent. If the rail cost $1,000, it would be a waste on this arithmetic, and you would not be negligent without it. Economists such as Richard Posner defend this as what courts already do. Critics reply that nobody knows P and L at the moment of decision, that the formula ignores rights and fairness (a cheap rule that trades life for money), and that juries rarely do the sum. Hand himself offered it only as a way of bringing the idea into relief, not as a sum courts must perform. Interactive · The Hand formula Cost of the precaution (B) Chance of the accident (P) Size of the loss (L) Negligence rule Strict liability rule A stylised model: the precaution removes the risk, and the numbers are illustrative. Real cases rarely supply P and L so neatly. Notice the neat result the tool shows: under both rules the careful choice is the same, and the total cost to society is the smaller of B and P × L. What differs is who ends up paying when the precaution isn't worth taking. Under negligence the victim carries the loss in that case; under strict liability the injurer does. That is the whole case for and against strict liability in one line. Causation: was it really the defendant? Fault is not enough: the claimant must show the fault caused the harm. The usual test is "but for": but for the defendant's act, would the harm have happened? If a driver is speeding but the pedestrian would have been hit at a legal speed, the speeding was not a cause. Courts then add a second filter, because causes ripple outward for ever: proximate or "legal" cause in the US (Palsgraf again), and in German and many Spanish-language courts "adequate causation" (adäquate Kausalität), meaning the harm must be a not-unlikely result of the act. Different tools, similar question: how far down the chain should a person answer for what they started? The hardest cases are the uncertain ones: a doctor delays a diagnosis, and the patient had perhaps a 40% chance of surviving anyway. The common law's civil standard is the balance of probabilities: more likely than not. It is all-or-nothing. If the claimant proves it over 50%, the defendant pays everything; at 49% nothing. English courts held this in Hotson v East Berkshire Health Authority (1987) and refused to compensate a lost chance in Gregg v Scott (2005). French law accepts the perte de chance as a harm in itself, and compensates the lost chance in proportion. Some US states (Herskovits v Group Health, Washington, 1983) allow it in medical cases. See what the rule does across many cases. Interactive · How sure must the court be? Chance the defendant caused the harm Straight line: pay in proportionStep: all-or-nothing at 50% Imagine 100 identical cases, each with a loss of 100 units, where the defendant truly caused the harm in the share shown. Illustrative only. With the slider on 60%, the all-or-nothing rule makes the defendant pay in all 100 cases (10,000 units) though they caused only 60 of the harms (6,000): they overpay by 4,000. At 40% they pay nothing though they caused 4,000 of harm. The proportional rule gets both right on average but demands the court assign percentages, and it lets a claimant recover something from a weak case. Neither is neutral; each trades accuracy against simplicity. Strict liability and products: paying without fault For some activities the law decides not to ask about fault. The English case Rylands v Fletcher (1868) made a landowner liable when a reservoir he built burst into a neighbour's mine shafts, even if he'd been careful: he brought a dangerous thing on his land. US law kept a descendant for "abnormally dangerous activities". The idea reached its biggest scale in products. In Greenman v Yuba Power Products (California, 1963) the court held that a manufacturer is strictly liable in tort when a product with a defect injures a user; the idea was written into the Restatement (Second) of Torts §402A in 1965. Europe's Product Liability Directive of 1985 (85/374/EEC) set a regime across the EU in which the producer is liable for damage caused by a defective product regardless of fault. A defect means the product wasn't as safe as a person is entitled to expect. The EU replaced that directive with a new one, Directive (EU) 2024/2853, adopted on 23 October 2024. Member states must transpose it by 9 December 2026. It extends the notion of a "product" to include software and digital manufacturing files, which the 1985 text, written for physical goods, left uncertain. Latin America took a consumer-law route: Brazil's Consumer Defence Code (Law 8.078 of 1990) made suppliers answerable for product defects without fault, and Argentina's consumer statute (1993) does the same, joined by its 2015 Civil and Commercial Code, which treats damage caused by risky things as strict liability. Design is where strict liability and fault meet: US law judges a design by weighing risk against a reasonable alternative design, close to a negligence test in disguise. Interactive · What must the claimant prove? Fault-based rule Strict product liability Simplified teaching cases; not a prediction of any real claim. Compensation: juries, punitive damages and the rest of the world Once liability is settled, how much? Everywhere, the basic aim is compensatory: German BGB §249(1) puts it neatly, restore the situation that would exist if the harm had not happened. Money for medical bills and lost earnings can be added up. Money for pain, grief or disfigurement cannot, and the families handle it differently. Germany allows money for non-pecuniary harm only where the law provides, notably bodily injury, health and liberty (§253). France compiled a standard list of harms (the Dintilhac nomenclature, 2005) that judges apply. Spain has a statutory scale for traffic injuries (the baremo, revised in 2015). Brazil's 1988 Constitution expressly protects compensation for moral and image damage. In the US, civil juries often set these amounts, which is one reason the headline numbers there are larger and more variable. The sharper contrast is punitive damages, an extra sum meant to punish and deter rather than compensate. They exist in the US and, within narrow categories, in England (Rookes v Devlin, 1964). Most civil-law systems keep punishment for criminal law, and in 1992 Germany's Federal Court of Justice declined to enforce the punitive part of a California judgment. A few states bar punitive damages, and many cap them. On the federal level the Supreme Court has set outer limits: BMW v Gore (1996) found one award grossly excessive; State Farm v Campbell (2003) said that few awards exceeding a single-digit ratio of punitive to compensatory damages will satisfy due process and that, where compensatory damages are substantial, a 1:1 ratio can be the outer limit; Exxon Shipping v Baker (2008) fixed 1:1 for that maritime case. The best-known case is also the most misreported. In Liebeck v McDonald's (New Mexico, 1994), a 79-year-old woman was badly burned by coffee in her lap. The jury found McDonald's 80% at fault and her 20%, set compensatory damages at $200,000 (reduced to $160,000) and punitive damages at $2.7 million, which it tied to about two days of the chain's coffee sales. The judge cut the punitive award to $480,000, three times the compensatory sum, and the parties then settled for an undisclosed amount. Try the ratio yourself. Interactive · Compensatory and punitive damages Compensatory award Punitive award Liebeck: jury Liebeck: after the judge Compensatory only The ratio zones are the US Supreme Court's guideposts (State Farm, 2003), not rules. Other systems are shown for contrast. What a graduate just sees Every accident forces a choice of who absorbs the loss: victim, injurer, insurer or the public. Fault means falling below a standard, and the Hand formula is the cleanest way to see why: skimping is careless when the precaution is cheaper than the expected harm. Negligence and strict liability give the same incentive to take cheap precautions; they differ on who pays when it was not worth it. A cause isn't just "but for": courts also ask how far down the chain responsibility should run. Proof at 51% can mean 100% of the bill, which is why some systems pay for lost chances in proportion. Products are a special case: the maker pays for defects without fault, because the maker is best placed to prevent them and spread the cost. Damages compensate; only some systems punish, and the biggest headline awards usually shrink on appeal. Where it shows up next Criminal Law & Procedure (35/07): the same acts may be both a crime and a tort, with different standards of proof and different goals. Administrative Law (35/09): can you sue a government for a pothole or a wrongful order? Civil Procedure & Evidence (35/08): the balance of probabilities is a rule about proof, not about the world. The real world: insurance premiums, product recalls, the warning labels on ladders, medical malpractice cover, and the EU's rules for digital products and AI-related harm. If you want to go deeper 📘 Textbook. John Goldberg, Anthony Sebok and Benjamin Zipursky, Tort Law: Responsibilities and Redress (Aspen/Wolters Kluwer). A widely used American casebook with a clear theory of what torts are for. 📘 Textbook. Winfield and Jolowicz on Tort (Sweet & Maxwell), the standard English treatise. 📘 Comparative. Konrad Zweigert and Hein Kötz, An Introduction to Comparative Law (Oxford University Press, 3rd ed., 1998), whose chapters on tort contrast the common law, French and German approaches. 🎬 Gentler. Hot Coffee (HBO documentary, 2011, directed by Susan Saladoff) on the McDonald's case and the "tort reform" debate. It takes the claimants' side, so read it beside the critics. 🌐 Free. The Cornell Legal Information Institute's Wex entry on tort law, a free plain-English reference with links to cases. The takeaway Tort law answers who pays for an accident nobody promised to prevent. Fault is priced by comparing the cost of care with the expected harm; causation limits how far liability runs; strict liability moves cost to whoever can best prevent or spread it; and compensation is about repair everywhere, with punishment as a mostly American extra. Try this: this week, pick a small risk you noticed (a loose step, an unlit path). Guess B, P and L, and ask whether the owner would be negligent under the Hand formula, and who ends up paying if nobody fixes it. Sources & Further Reading Sources. Cases: Palsgraf v Long Island Railroad, 248 NY 339 (1928); Donoghue v Stevenson [1932] AC 562; Caparo v Dickman [1990] 2 AC 605; United States v Carroll Towing, 159 F2d 169 (2d Cir 1947); Hotson v East Berkshire HA [1987] AC 750; Gregg v Scott [2005] UKHL 2; Herskovits v Group Health, 99 Wn 2d 609 (1983); Rylands v Fletcher (1868) LR 3 HL 330; Greenman v Yuba Power Products, 59 Cal 2d 57 (1963); Rookes v Devlin [1964] AC 1129; BMW v Gore, 517 US 559 (1996); State Farm v Campbell, 538 US 408 (2003); Exxon Shipping v Baker, 554 US 471 (2008). Statutes: French Code civil art. 1240 (formerly 1382); BGB §§249, 253, 276, 823 (gesetze-im-internet.de); Mexican Código Civil Federal art. 1910; Directive 85/374/EEC; Directive (EU) 2024/2853 (adopted 23 Oct 2024, published 18 Nov 2024, transposition by 9 Dec 2026). Liebeck facts: Cornell LII and press accounts agree on the verdict and reduction; the settlement is confidential. The ratio zones are those stated in State Farm. Interactive numbers were computed in node. This describes how legal systems work; it is not legal advice. 📘 Goldberg, Sebok & Zipursky, Tort Law: Responsibilities and Redress 📘 Zweigert & Kötz, An Introduction to Comparative Law 🌐 Cornell LII Wex: Tort 🌐 EUR-Lex: Directive (EU) 2024/2853 Step 5. Criminal Law & Procedure: Guilt, Proof and Who Runs the Trial --------------------------------------------------------------------- Why: Crime, guilt and fair trials, adversarial and inquisitorial. Every legal system has to decide when the state may punish a person, and how sure it must be first. The answers differ more in how the trial is run than in what counts as a crime. A man is arrested for a robbery he did not commit. He is told that if he goes to trial and loses he faces ten years, but if he admits the lesser charge today he can go home in two. He thinks there is a one in three chance a jury convicts him. What should he do? Nearly everyone who hears the numbers says the same thing, and it is not "fight for the truth". That small, ugly calculation is the hidden centre of criminal justice in many countries. A first-year criminal law course teaches the two halves behind it. Substantive criminal law asks what counts as a crime and what mind a person must have had. Procedure asks how the state may investigate, charge, try and convict, and what happens when it gets it wrong. A graduate keeps seeing both at once: a rule about guilt is only as good as the way guilt is proved. This piece describes how legal systems work. It isn't legal advice, and laws differ by country and change. If you are facing a charge, speak to a qualified lawyer where you live. The course in one box Who takes itEvery law student. In the US it is a first-year course (with criminal procedure often a second-year elective); in the five-year degrees of Spain, Mexico, Argentina and Chile, and in Germany's state-exam subjects, criminal law is a core early subject, with procedure taught as a separate course. What it is forDeciding when the state may punish someone, what it must prove, and by what process. Comes afterLegal Reasoning & Writing (35/02) and Constitutional Law (35/03). Leads toInternational Law & Human Rights (35/10), where fair-trial rights are set down for every country. It also pairs with Cognitive Psychology (35/22, why eyewitness memory fails) and Game Theory (34/45, the strategy of bargaining). What this piece gives youYou won't be able to defend or prosecute anyone. You will see the five questions every criminal system answers, and why two honest countries can try the same crime in very different ways. Easier first reads: Rights, Constitutions and the Rule of Law (18/04) and Justice: Plato to Rawls, Nozick and Sen (05/13). This piece goes further into how guilt is actually decided. The common ground, and four ways to answer it Every society has the same problem. Some harms are too serious to leave to the victim and the offender to sort out, so the community, through the state, takes over: it names the conduct, finds the person, and decides on a penalty. That brings two dangers of its own. Power to punish can be turned on enemies, and any process can convict the wrong person. So every modern system answers the same five questions. What conduct is forbidden? What must be proved about the person's mind? What excuses or justifications are allowed? Who investigates and judges? And how sure must the judge be? The first answer is nearly universal: no crime without a prior law, in Latin nullum crimen sine lege. You cannot be punished for something that was lawful when you did it. The US Constitution bans ex post facto criminal laws (Article I, sections 9 and 10). Germany's Basic Law says an act is punishable only if the law defined it as an offence before it was committed (Article 103(2)). Argentina's constitution (Article 18) says no inhabitant may be punished without a trial based on a law in force before the offence, and Mexico's (Article 14) forbids imposing a penalty by simple analogy. The European Convention on Human Rights (Article 7) and the International Covenant on Civil and Political Rights (Article 15) say the same for dozens of countries. The rule is the reason criminal statutes must be written down and precise. FamilyHow crime is written downHow the trial is run United States (common law; England and Wales are the source)Mostly statutes today, but built on common-law ideas such as mens rea; 50 state codes plus federal law. The Model Penal Code (1962) is an influential, non-binding template.Adversarial: prosecution and defence present their cases to a neutral judge and, for serious crimes, a jury. About nine in ten convictions come from guilty pleas. Latin America (civil-law codes: Mexico, Argentina, Brazil, Chile, Colombia)A penal code per country, with constitutional rights written into the constitution.Inquisitorial, file-based procedure for most of the 20th century, replaced since the 1990s by oral, accusatory trials. Brazil keeps a jury for intentional killings. Mexico, Chile and Colombia have all rewritten procedure. Continental Europe (France, Germany, Spain; the Council of Europe)Codes. France's current penal code dates from 1994; Germany's from 1871, much amended. The European Convention applies across the continent.Judges play an active role in finding the facts, and ordinary people sit as lay judges or jurors beside professionals in serious cases. Limited forms of negotiated justice have been added since the 1980s. Mixed and other systems (Scotland, South Africa, Louisiana, Quebec; Islamic and customary law)Blends of the above. Some states apply criminal rules drawn from religious law; customary systems handle many local disputes.Varies. Treat each on its own terms rather than as a variation on one of the others. Real systems drift towards each other. The "adversarial versus inquisitorial" split is a useful map, not a wall. England, Germany and Mexico all now claim to guarantee a fair, public, reasoned trial; they simply give the judge, prosecutor and defence different jobs inside it. Guilty act, guilty mind, and the defences Most crimes need two things at once. Actus reus is the guilty act (or sometimes a failure to act where there is a duty): the conduct, the circumstances, often a result such as a death. Mens rea is the guilty mind: what the person knew, meant or risked. The old slogan, actus non facit reum nisi mens sit rea, says an act does not make a person guilty unless the mind is guilty too. Shooting someone who stepped in front of a hunter's rifle at the last second is not a murder. Law does not treat "a guilty mind" as one thing. The American Model Penal Code ladders it into four levels: acting purposely, knowingly, recklessly (consciously running an unjustified risk) and negligently (failing to see a risk a reasonable person would). Continental codes draw a similar line between Vorsatz in German and dolo in Spanish (intent, including accepting a likely result, called dolus eventualis or dolo eventual) and Fahrlässigkeit or imprudencia (negligence). Higher states of mind are punished more; some low-level offences ask for none at all and are called strict liability. Interactive · Which offences can the prosecution prove? Swerves to miss a child Texts while driving Races through a town Cuts a brake line Means to kill State of mind the court finds A simplified ladder in the style of the Model Penal Code. Real homicide offences differ by country (many systems treat extreme recklessness as murder) and each also needs an act that causes a death. Illustrative, not a statement of any one law. Look at what the sliders show. The same death is "no crime", a negligence offence, manslaughter or murder depending only on what was in the head of the person involved, which is why so much of a criminal trial is the proof of a state of mind from outward facts. Defences come in two kinds, and lawyers keep them apart. A justification says the act was right, or at least permitted: self-defence, defence of others, necessity. An excuse says the act was wrong but the person is not blameworthy: insanity (the English M'Naghten rules of 1843 are the classic test; countries now use a range of formulas), duress, and in many systems youth. German doctrine makes this structure explicit in three steps: a defined offence (Tatbestand), then no justification (Rechtswidrigkeit), then personal guilt (Schuld). Common-law courses reach the same distinctions with less tidiness. Two ways to run a trial: a contest or an inquiry Picture a dispute about what happened. One way to find out is to let the two sides fight it out in front of a referee who does not take sides: this is the adversarial idea, from England and now the United States. The other is to appoint an official to find out the truth and report to the court: this is the inquisitorial idea, developed on the European continent from the medieval church courts and the state courts that followed. In the adversarial picture the parties own the case. In the inquisitorial picture the court owns it. No country is pure. The comparative-law scholar Mirjan Damaška, in The Faces of Justice and State Authority (1986), argued that what differs is less the label than how authority is organised: whether power is concentrated in a hierarchy of officials or spread among competing parties. Try the roles in three common settings. Interactive · Who does what in the courtroom? Adversarial (US, England) Continental (France, Germany) Reformed Latin America Simplified outlines of the usual pattern in serious cases. Details differ by country, court and offence. Latin American systems differ among themselves; the reformed pattern shown is the one adopted by Chile, Colombia and Mexico. Notice the trade. In a contest, a well-funded defendant can probe the state's case hard, and an under-funded one can be steamrolled. In an inquiry, the court is meant to look for exculpatory evidence as well as incriminating evidence, but a judge who has read the entire file may have formed a view before the trial begins. Many Latin American reformers took exactly that second worry to heart, as the next sections show. Plea bargaining: the trial that almost never happens The United States Constitution promises a jury trial. In practice, the Sentencing Commission's figures for the federal courts show that in fiscal year 2023 about 97% of the 64,124 offenders sentenced had pleaded guilty, and only about 3% went to trial. State courts are less well counted, but the figure is commonly put near 90%. The Supreme Court has held that prosecutors may offer lower charges or sentences for a plea, and may threaten harsher charges if a defendant refuses (Bordenkircher v. Hayes, 1978). Critics call this a "trial penalty": defendants who exercise their right to trial risk much heavier sentences. Defenders say plea deals save scarce court time and give both sides certainty. Other systems face the same pressure and respond differently. Italy introduced patteggiamento (negotiated sentence, with a reduction of up to a third) in its 1988 code. France created the comparution sur reconnaissance préalable de culpabilité ("plaider-coupable") in 2004, and by 2009 about 11% of its correctional-court decisions went that way. Germany, which long insisted that a court must find the truth itself, regularised agreements in 2009 (section 257c of the Code of Criminal Procedure), and in 2013 its Federal Constitutional Court criticised informal "deals" that skipped the safeguards. Latin American reforms generally added abbreviated procedures too; Argentina's juicio abreviado is a well-known example. Interactive · The plea calculator Chance a trial convicts Sentence if convicted at trial Sentence offered for a plea Expected trial sentence = chance of conviction × sentence; an acquittal counts as zero. Illustrative numbers, and it ignores risk-aversion, record and other costs. If the offer is larger than the trial sentence the tool caps it. With the default numbers (a 30% chance of conviction, ten years, a two-year offer) the expected cost of trial is 3.0 years, so pleading looks better unless the chance of conviction is under 20% (2 ÷ 10). A defendant who is truly innocent but cannot be confident of a jury faces the same arithmetic. That is the problem, and it is why criminal-procedure scholars worry as much about the incentive as the outcome. Latin America's shift to accusatory oral trials For most of the 20th century the typical Latin American criminal case was a written file passed between an investigating judge, a prosecutor and a clerk. The judge investigated, then often decided on the paper record; a defendant might never see the judge in a hearing. A wave of reforms, beginning in Central America in the 1980s and 1990s and reaching the largest countries last, replaced this with accusatory systems: the prosecutor investigates, a separate judge guards rights during the investigation, and a different judge or panel decides at an oral, public, adversarial trial. The details are best learned country by country. Chile's new code was introduced in stages from 2000 and was complete by about 2005 to 2006. Colombia's 2004 law began operating by judicial district in 2005. Mexico's constitutional reform of 18 June 2008 set an eight-year transition, a single national code of criminal procedure was published on 5 March 2014, and the deadline fell in 2016. Argentina's federal accusatory code (Law 27,063, 2014) was held back for years and has been switched on district by district since 2019, beginning with Salta and Jujuy; the rollout has continued since, with some dates moved. Mexico's own constitution now states that criminal proceedings "will be oral and adversarial" (Article 20). Interactive · A reform timeline Year Dates are for the national reforms named in the text; individual states, provinces and districts moved at different times, and the dates for Colombia and Argentina are the start of phasing in, not completion. Why do it? Reformers argued that the old system was slow, secret and left suspects in jail awaiting trial; open hearings let the public see how decisions were reached. Critics and evaluators have found mixed results. Trials are faster and more transparent in many places, but new systems have struggled with training, funding and with a heavy reliance on the same plea deals the reform was supposed to limit. The honest summary is that a procedural code can change what happens in a courtroom much faster than it can change a country's policing and prisons. Wrongful convictions: what the evidence shows Every system will sometimes convict the wrong person. How often is unknowable, because the cases we learn about are only those that get overturned. In the United States, the National Registry of Exonerations listed 3,698 known exonerations since 1989 as of June 2025. In its first 873 cases, mistaken eyewitness identification played a part in 43%, perjury or false accusation in 51%, and false confessions in 16%. In a famous 2014 study in the Proceedings of the National Academy of Sciences, Samuel Gross and colleagues estimated that at least 4.1% of defendants sentenced to death in the US would be exonerated if they stayed on death row indefinitely, and the authors warn that this cannot be extended to other crimes. Wrongful convictions are not only an American problem. Statistical error has produced them too. In 1999 an English solicitor, Sally Clark, was convicted of murdering her two baby sons after a paediatrician told the jury that the chance of two cot deaths in a family like hers was "1 in 73 million" (he had squared a single-death figure, wrongly treating the two deaths as independent). The Royal Statistical Society protested, and the convictions were quashed in 2003, after it emerged that evidence of infection in one baby had not been disclosed. The deeper error is the prosecutor's fallacy: confusing "the chance of this evidence if the person is innocent" with "the chance the person is innocent, given this evidence". Interactive · A one-in-a-million match Chance a random person matches People who could have done it Assumes the source is in the pool, everyone in the pool was equally likely beforehand, and the match is the only evidence. Real cases carry other evidence; the point is the shape of the arithmetic. Illustrative. A one-in-a-million match found by searching a city of a million people leaves roughly even odds that the person matched is the source, not a million to one. Reformers' answers are practical rather than philosophical: record interrogations, run lineups so that the officer does not know which person is the suspect, require corroboration of informants, preserve biological evidence, and give convicted people a real route to review. Many of these ideas come from psychology research on memory and interrogation (see Cognitive Psychology, 35/22). What a graduate just sees A crime is a wrong the state answers for, so the state must name it in advance and prove it. "Guilty" always has two halves: what was done and what the person's mind was doing. The same death can be an accident, negligence, manslaughter or murder, depending on the mental state. Justification says "it was right"; excuse says "it was wrong, but not blameworthy". "Adversarial" and "inquisitorial" describe who owns the case, and no real country is pure. When the trial penalty is large, almost everyone pleads, so the plea offer is the real sentence. A rare match is not the same as a rare innocence: always ask how many people could have matched. A new procedural code is easy to pass and slow to make real. Where it shows up next International Law & Human Rights (35/10): the fair-trial rights of Article 6 of the European Convention and Article 14 of the ICCPR are written for every system, whatever its style. Cognitive Psychology (35/22): eyewitness memory is the main factor in many wrongful convictions. Game Theory (34/45): a plea is a bargain under a threat, and its logic is a game. In the world: a prosecutor's office deciding which charge to file, a public defender with 100 open cases, a judge in Santiago or Monterrey running an oral hearing, a news story about a retrial. If you want to go deeper Standard textbooks: Joshua Dressler, Understanding Criminal Law (US-focused, clear on mens rea and defences); Andrew Ashworth and Jeremy Horder, Principles of Criminal Law (England and Wales, philosophical depth). Check for the current edition of each. For comparison: Mirjan Damaška, The Faces of Justice and State Authority (1986). Gentler: Brandon Garrett, Convicting the Innocent (2011), built on the first 250 DNA exonerations; or, as a story, John Grisham's The Innocent Man (2006), his one work of non-fiction. Free course: the Open University's OpenLearn unit Myths in law, an adapted extract from its criminal law and courts module. The takeaway Criminal law decides when the state may punish; criminal procedure decides how it must prove it. Guilt needs an act and a mind, and the state must have named the crime first. Systems differ most in who runs the trial, a referee between contesting sides or a court that inquires, and most real cases are decided before a trial through a plea. Latin America has spent thirty years moving from file to courtroom, and every system still has to guard against the persuasive, wrong conviction. Try this: next time you read about a verdict, ask three questions. What did the prosecution have to prove about the person's mind? Was it a trial, or a plea? And how many other people could have fit the evidence? Sources & Further Reading Sources. US Sentencing Commission, 2023 federal sentencing statistics (97.2% pleas of 64,124 cases); Bordenkircher v. Hayes, 434 U.S. 357 (1978); National Registry of Exonerations (3,698 as of 28 June 2025; percentages from the first 873 cases, per its Wikipedia summary); Gross, O'Brien, Hu & Kennedy, PNAS 111(20), 2014; Sally Clark case (convicted 1999, quashed 2003); Basic Law Art. 103(2); Argentina's constitution Art. 18; Mexico's constitution Arts. 14 and 20; Brazil's constitution Art. 5 XXXVIII; Mexican reform of 18 June 2008 and the CNPP of 5 March 2014; Argentina Law 27,063 (2014) and the federal rollout from 2019. Plea bargaining in France, Germany and Italy: Wikipedia summary of national codes. Model Penal Code (American Law Institute, 1962). Damaška (1986). Dates for Chile and Colombia are approximate and come from a World Bank-style summary of the regional reforms. 🌐 OpenLearn: Myths in law 🌐 US Sentencing Commission: 2023 Federal Sentencing Statistics 📘 Dressler, Understanding Criminal Law 📘 Garrett, Convicting the Innocent Step 6. Constitutional Law: The Rules for the People Who Make the Rules ----------------------------------------------------------------------- Why: Constitutions, rights and the courts that guard them. Every country has to decide who may tell the government "no", and what happens when a parliament passes a law that breaks the highest law. The American, European and Latin American answers are different inventions, and each one fits the history that produced it. A legislature passes a law. A citizen says it violates her rights. Who decides? The legislature itself has an obvious interest in saying no. The executive, who enforces the law, has an interest too. So societies have invented an outsider: a judge, or a special court, whose job is to say that the law, though properly passed, is void. Where that power sits, who may invoke it, and what a ruling does afterwards are the main differences between constitutional systems. In the United States any court can refuse to apply an unconstitutional law. In Germany, only one court can strike it down. In Mexico, a man can go to a federal judge in person and ask for protection, called an amparo, but the ruling will traditionally protect him alone. These are three solutions to the same problem. This piece describes how constitutional systems work and is not legal advice; constitutions and court rules differ by country and change, and some systems (Mexico's judiciary, for one) have been reformed recently, so check current sources. The course in one box Who takes itLaw students in year 2 (the US first-year or second-year core; a core course in Europe and Latin America), plus political-science students. Constitutional law is also taught as "public law" or "derecho constitucional", and comparative constitutional law is an elective in many programmes. What it is forUnderstanding the highest rules in a country: how power is organised and limited, what rights are protected, and who has the last word. Comes afterLegal Systems of the World (35/01). Leads toCriminal Law & Procedure (35/07), Administrative Law (35/09), International Law & Human Rights (35/10) and European Union Law (35/11). It is also a core course in Political Science (see Comparative Politics, 35/13). What this piece gives youYou will not be able to brief a constitutional case. You will see the main designs for judicial review, why a Mexican amparo and a German constitutional complaint work differently, and what an amendment rule says about a country. Easier first reads: Rights, Constitutions & the Rule of Law (18/04) and How a Law Gets Made (18/07). Why a constitution: rules about the rule-makers A constitution does two jobs. It organises power (who makes laws, who enforces them, how courts are chosen, how regions fit in) and it limits power (rights that even a majority cannot simply vote away). Those two jobs require one more feature: it must be harder to change than an ordinary law. A constitution that parliament could rewrite by a simple vote would limit nothing. That is why every serious constitution has special rules for its own amendment, which we return to at the end. Constitutions come in many sizes. The US Constitution of 1789 has seven articles and 27 amendments. Brazil's 1988 Constitution is a large document that goes into detail on social rights. Mexico's 1917 Constitution, born of the Revolution, was one of the first to include social rights such as labour protections. The United Kingdom has no single codified constitution; its fundamental rules are spread across statutes, court decisions and conventions, and Parliament is sovereign. The question "who has the last word?" gets a different answer in each. Judicial review: who decides when a law breaks the constitution? The American story starts with Marbury v. Madison, decided on 24 February 1803 (5 U.S. (1 Cranch) 137). Chief Justice John Marshall, writing for the Court, held that a provision of the Judiciary Act of 1789 gave the Supreme Court a power the Constitution did not, and that a law contradicting the Constitution could not stand. His reason, in one line: "It is emphatically the province and duty of the judicial department to say what the law is." The Constitution does not say in terms that courts may strike down laws; Marshall derived it from the Constitution's status as supreme law, an argument that Alexander Hamilton had already made in Federalist 78. The result is a diffuse model: any court, deciding any ordinary lawsuit, can refuse to apply a statute that violates the Constitution, and the Supreme Court has the last word. Europe took a different path. The Austrian jurist Hans Kelsen argued that having every judge decide constitutional questions would produce chaos and that the job needed one special court. Austria's 1920 constitution created such a court, the first in a form Kelsen designed; Czechoslovakia's 1920 constitution also provided for one, which first sat in 1921. After the Second World War, Germany (Basic Law of 1949, with the Federal Constitutional Court beginning work in 1951), Italy, and later Spain and Portugal built their own. Under this concentrated model, ordinary judges cannot strike down a statute; if they think one is unconstitutional, they stop the case and refer the question up. When the constitutional court annuls a law, it is gone for everyone. Kelsen called the court a "negative legislator". Many countries mix the two. Brazil lets any judge set aside an unconstitutional law in a case, while the Supreme Federal Court also hears direct challenges whose results bind everyone. Colombia's Constitutional Court (created by the 1991 constitution) hears abstract challenges and reviews rights decisions from lower courts. France, which long distrusted judges overruling parliament, created the Conseil constitutionnel in 1958 to check bills before promulgation, and since 2010 lets litigants raise constitutional questions about laws already in force. The United Kingdom keeps parliamentary sovereignty: courts can declare a statute incompatible with human rights (Human Rights Act 1998), but the statute remains valid until Parliament changes it. Interactive · A law is challenged. What happens? Simplified summaries of each system's main route. Each country has several, with deadlines and conditions. Mexico's judicial institutions were restructured by a 2024 constitutional reform; check current rules. Amparo: rights you can take to court yourself Latin America's characteristic invention is a fast, simple court action for someone whose constitutional rights are being violated. It began in Mexico. Manuel Crescencio Rejón designed the first version in the 1841 constitution of the state of Yucatán, and Mariano Otero carried it to the federal level in the Acta de Reformas of 1847. It was repeated in the federal constitutions of 1857 and 1917 (article 107 in the current one). Otero's rule, the Otero formula, says an amparo ruling protects only the person who asked for it. The law may remain on the books, and a neighbour whom it also hurts has to file her own case. The idea spread. Argentina's Supreme Court recognised amparo by decision in the Siri case (1957), followed the next year by Kot; a statute followed in 1966, and the 1994 constitutional reform wrote it into article 43. Colombia's 1991 constitution created the tutela (article 86), a rapid action that any person can bring before any judge. Chile has a recurso de protección for rights violations. Spain and Germany reached a similar place from Kelsen's direction: Spain's recurso de amparo and Germany's Verfassungsbeschwerde let individuals bring complaints to the constitutional court after other courts have ruled. The United States has no stand-alone equivalent; individuals raise constitutional claims inside ordinary lawsuits, in criminal defences, in habeas corpus petitions, or in civil-rights suits against officials. Compare the effect of a ruling. Under the Otero formula, 100 people may be hurt by a law, but if only 20 sue, 20 are protected. Under Kelsen's model, once the constitutional court annuls the law, everyone is protected. Mexico's 2011 reforms opened a route to a general declaration of unconstitutionality after repeated rulings, with a demanding voting threshold, so the formula is no longer absolute. The trade-off is real: relative effects respect the legislature and the individual case, but leave people unprotected unless they can afford to sue; general effects protect everyone but give a court the power to remove a law. Interactive · One bad law, a crowd of people Relative effect (Otero formula) General effect (law annulled) People the law affects Share who file a case in time Arithmetic on invented numbers to show the structure. Real systems have filing deadlines, class and collective actions, and government practice of following rulings. Rights and their limits: tiers of scrutiny and proportionality No right is absolute. Free speech yields to defamation law; property to taxation. So the question in a rights case is always: when is a restriction justified? Systems have developed two main structures for answering. US courts apply tiers of scrutiny. The more important the right (or the more suspect the classification), the harder the government's job. Under rational-basis review, a law survives if it is rationally related to a legitimate aim. Under intermediate scrutiny, the aim must be important and the means substantially related to it. Under strict scrutiny, the aim must be compelling and the law narrowly tailored, which in practice means no less restrictive way would do. The famous footnote 4 of United States v. Carolene Products (1938) is usually credited with hinting that laws burdening certain rights and minorities deserve closer inspection. Germany, and many courts influenced by it (including Canada's, after R. v. Oakes in 1986, and the European Court of Human Rights), use proportionality. The court asks four questions in order: is the aim legitimate? is the measure suitable to achieve it? is it necessary, meaning is there a less restrictive way that would work as well? and is it proportionate in the strict sense, meaning do the benefits outweigh the harm to the right? The German Federal Constitutional Court's Lüth decision (1958) is a classic starting point for the idea that rights are not only shields against the state but also values that shape the whole legal order. Proportionality has a built-in balance; tiers have a built-in sorting step. Critics of proportionality say it lets judges substitute their own weighting for the legislature's; critics of tiers say the sorting is arbitrary and hides the real weighing. Both camps are serious. Interactive · Test a restriction two ways Scenario (invented): a city bans all marches on its main road at rush hour. Set how strong the city's reason is, how much it cuts into the right, and whether a lighter option (such as lane closures) would do. Political speech Commercial advertising Business licensing Strength of the city's reason (1 to 5) Severity of the restriction (1 to 5) A lighter alternative exists No lighter alternative A toy model of the structure of each test, with invented thresholds; it does not predict any court's result. Splitting power: separation and federalism Constitutions also fight tyranny by dividing power. Montesquieu's The Spirit of the Laws (1748) argued that liberty is safest when the powers to make, enforce and judge laws are held by different hands. James Madison, in Federalist 51 (1788), turned it into a design principle: "Ambition must be made to counteract ambition." Different bodies, with different interests, check each other. Constitutions arrange the pieces differently. In a presidential system, an elected president and the legislature have separate mandates and can end up in opposition; the US, Mexico, Argentina, Brazil, Chile and Colombia are examples. In a parliamentary system (Germany, Spain), the government depends on the confidence of the legislature, so there is less separation but fewer deadlocks. France is semi-presidential. And power is divided vertically, too: federal states (the US, Mexico, Argentina, Brazil, Germany) give regions constitutional powers that the centre cannot simply take away; unitary states (France, Chile, Colombia) delegate power downwards. Spain sits between, with autonomous communities. The US presidential veto shows the mechanics. The Constitution (Article I, section 7) lets the president veto a bill; Congress can override with a two-thirds vote in each chamber. Notice that the 60-vote threshold that often decides what passes in the Senate is not in the Constitution at all. It is a Senate rule, which the Senate can change. Interactive · Can the opposition get its bill past a veto? Share of seats held by the president's opponents (both chambers) US Congress sizes: House 435 seats, Senate 100. Assumes every member votes the party line and all are present; real votes are messier, and a 50-50 Senate is broken by the vice-president. Changing the constitution: how hard should it be? The amendment rule is a constitution's way of describing how much it trusts the present. If it is too easy to change, the document protects nobody. If it is too hard, it freezes the arrangements of a past generation and pressure builds up elsewhere, often in judicial interpretation. The US Constitution requires two-thirds of both houses of Congress (or a convention called by two-thirds of the states), then ratification by three-quarters of the states: 38 of 50. Only 27 amendments have passed since 1789, the first ten in 1791. Germany needs two-thirds of the Bundestag and two-thirds of the Bundesrat votes (Basic Law, Article 79(2)); and Article 79(3) puts some principles, such as human dignity and the federal, democratic and social character of the state, beyond amendment altogether. Brazil requires three-fifths of the members of each house in two rounds of voting (Article 60), and also protects a core of "stone clauses" from change. Mexico requires two-thirds of the legislators present in Congress and then approval by a majority of the state legislatures (Article 135). Spain's ordinary route needs three-fifths of each chamber, and a stricter route with a referendum exists for the most basic provisions. Courts can also police the limits. India's Supreme Court held in Kesavananda Bharati (1973) that Parliament's power to amend does not extend to destroying the constitution's "basic structure". And when a country tries to replace its constitution altogether, it can fail: in Chile, voters rejected a proposed new constitution in a plebiscite on 4 September 2022, with 61.87% voting against. Interactive · Could this amendment pass? Legislators in favour Second body in favour Main route only; shares are of the body described (members, members present, or states, as the country's rule says). Some countries add referendums or other routes. Thresholds are examples for learning, not advice. What a graduate just sees Ask who has the last word on a constitutional question, and what their ruling does to the law afterwards. "Diffuse" (any judge) and "concentrated" (one court) are two designs for judicial review, and many countries mix them. An amparo-style remedy brings the constitution to the individual; the price is that relative effects leave the law standing for everyone else. A right is a claim plus a test for when it can be limited, and the test (tiers or proportionality) shapes outcomes. Separation of powers is built from veto points. Count them to predict how hard it is to change anything. An amendment rule shows how much a constitution trusts the present. Easy rules invite rewriting; hard rules invite creative interpretation. Rules of a legislature (like the 60-vote Senate threshold) are not the same as rules of the constitution. Where it shows up next Administrative Law (35/09): the constitutional limits on agencies, and the courts that check them. Criminal Law & Procedure (35/07): the rights of the accused are mostly constitutional rights. International Law & Human Rights (35/10) and European Union Law (35/11): when a regional court or treaty sits above the national constitution, or a constitution makes a treaty equal to it. Comparative Politics (35/13): how electoral rules and the executive-legislature relationship shape stability. In the world: every news story about a court striking down a law, a government refusing to obey a ruling, or a country drafting a new constitution. If you want to go deeper 📘 Textbook. Erwin Chemerinsky, Constitutional Law: Principles and Policies (Wolters Kluwer/Aspen; use the latest edition). A standard US law-school text. 📘 Textbook. Vicki C. Jackson and Mark Tushnet, Comparative Constitutional Law (Foundation Press). The standard comparative casebook, including Kelsenian courts and proportionality. 📘 Gentler. Akhil Reed Amar, America's Constitution: A Biography (Random House, 2005), a readable story of the US text; and Mark Tushnet, Advanced Introduction to Comparative Constitutional Law (Edward Elgar) for the wider world. 🌐 Free course. MIT OpenCourseWare 17.245 Constitutional Law: Structures of Power and Individual Rights (Spring 2013), covering judicial review, federalism and separation of powers through US cases. For the texts of the world's constitutions, the Constitute project publishes them in searchable form. The takeaway A constitution organises and limits power and is harder to change than ordinary law. Someone has to say when a law breaks it: any judge in the American model, one special court in Kelsen's, or a mix. Latin America added the amparo, which brings the constitution to the individual. And every design embodies a trade-off between the legislature's power, the individual's protection and the court's authority. Try this: find the amendment clause of a constitution you care about (the Constitute site has them) and work out how many people have to say yes. Then ask whether that country amends its constitution often or rarely. Sources & Further Reading Sources. Marbury v. Madison, 5 U.S. (1 Cranch) 137 (decided 24 February 1803), opinion by Chief Justice Marshall; the quoted sentence is from the opinion. Federalist 51 (1788) and 78. Kelsen and the Austrian and Czechoslovak courts: Wikipedia, "Constitutional court" (Czechoslovak constitution of 1920, court convened 1921; Austrian court; German Basic Law 1949). Amparo history (Rejón, Yucatán 1841; Otero, Acta de Reformas 1847; the Otero formula in the 1857 and 1917 constitutions): academic and Mexican congressional sources. Argentina's Siri (1957), Kot (1958), Law 16,986 (1966), article 43 (1994) and Colombia's tutela (article 86): Spanish Wikipedia, "Acción de amparo". German Basic Law Article 79(2) and (3): the Federal Ministry of Justice's English translation. Brazil Constitution Article 60 (three-fifths of each house, two rounds). Mexico Constitution Article 135 (two-thirds of those present and a majority of the state legislatures). Chile's 2022 plebiscite: 61.87% reject, 4 September 2022 (Wikipedia, citing the electoral service). Tiers of scrutiny, proportionality, Carolene Products (1938), Lüth (1958), R. v. Oakes (1986), Kesavananda Bharati (1973): standard constitutional-law texts. US congressional sizes and veto rules: Article I. This piece describes how constitutional systems work and is not legal advice. 📘 Jackson & Tushnet, Comparative Constitutional Law 📘 Amar, America's Constitution: A Biography 🌐 MIT OCW 17.245 Constitutional Law 🌐 Constitute: the world's constitutions Step 7. Property: Who Gets to Say No ------------------------------------ Why: What it means to own something. Ownership is a bundle of rights, proved by paper or a register, ripened by time, and limited by everyone else. Every legal family builds the bundle differently. A man puts up a fence. Another man, three streets away, plants his flag on a mountain and says he owns it. A farmer in Oaxaca can pass his field to his daughter but not sell it to a stranger. A songwriter's lyrics are protected for seventy years after she dies in much of the world, and for a hundred in Mexico. Each of these is "property", and each works differently. A law graduate hears the word mine and asks, almost without noticing: mine against whom, for how long, and who says so? Every society must answer how people get to use things that other people also want. Allow no exclusive claims and nobody will invest in a field or a house. Allow too many, with no limits, and some people end up with nothing and the common good is lost. Property law is the long, patched-together answer. It is also where the world's legal families, and the world's peoples, differ most about what a "right" even is. This describes how legal systems work. It isn't legal advice; laws differ by country and change. The course in one box Who takes itEvery law student: Property is a first-year course in the US; in the five-year degrees of Spain, Mexico, Argentina and Chile it is "derechos reales" (real rights) in the early years; in Germany Sachenrecht sits beside the law of obligations in the state-exam core. Surveyors, planners and economists meet parts of it. What it is forSaying who may use, sell and exclude others from a thing, how that is proved, and when the right expires or must give way. Comes afterLegal Systems of the World (35/01). Leads toNothing else in the major requires it, but it feeds Constitutional Law (35/03), whose property clauses protect owners; Civil Procedure & Evidence (35/08), where land disputes are decided; and International Law & Human Rights (35/10), which covers indigenous land rights. What this piece gives youYou won't be able to say who owns a particular plot. You will see why "ownership" is a bundle of separate rights, how a squatter can become an owner, why land registers exist, why shared pastures decay without rules and why some thrive, and why the same song can be free to copy in one country and protected for decades more in another. Easier first reads: Political Economy (31) for the big systems that set property rules, and Rights, Constitutions & the Rule of Law (18/04). The common ground: who gets to say no? Strip away the vocabulary and every system asks the same questions about a thing. Who may use it? Who may stop others? How can the right be passed on, and how can a buyer be sure the seller really has it? What happens when someone has treated it as theirs for a long time? And when can the state, or the community, override the owner? The families answer these with different instincts: the common law with a patchwork of "estates" and decades of judicial gloss; the civil codes with Roman-law ownership (dominium, propiedad) as a single, strong right and a short list of lesser "real rights" such as usufruct and servitudes. QuestionUS and EnglandLatin AmericaFrance and Germany Core ideaA bundle of rights; land held as an estateOwnership (propiedad) as a strong right with a social functionOwnership as the fullest right over a thing, with duties Proof of titleUS: recorded deeds plus title insurance. England: a state registerProperty registries, usually state or provincialGermany: the Grundbuch register. France: notaries and recorded deeds Long possessionAdverse possessionUsucapión / prescripción adquisitivaUsucapion / Ersitzung Communal rightsCommons, trusts, native titleEjidos, resguardos, indigenous territoriesCommons and communal lands exist; fewer in the codes What ownership is: a bundle with duties Ask a layperson what ownership is and they say "it's mine". A lawyer says it is a bundle of separate rights that can be held by different people. The Oxford jurist Tony Honoré, in a 1961 essay, listed the "standard incidents" of full ownership: the rights to possess, use, manage, take the income, transfer, leave to heirs, and use it as security, along with the duty not to use it to harm others and the liability to have it taken for a debt. Each can be handed out separately: a tenant gets possession and use, a lender gets security, a trust gives income to one person and control to another. The codes begin with a strong right and then qualify it. The French Code civil (art. 544) describes ownership as the right to enjoy and dispose of things in the most absolute manner, provided no use is made that laws or regulations forbid. Germany's BGB §903 lets the owner deal with a thing as he likes within the law and others' rights, and the Grundgesetz (art. 14) adds that "property entails obligations": its use should also serve the public good. Mexico's Constitution (art. 27, 1917) goes furthest: land and water within the territory belong originally to the Nation, which may transmit ownership to individuals as private property, and may impose limits on it for the public interest. Whichever the starting point, the endpoint is the same: no owner has an unlimited right. Interactive · Who holds which rights? Simplified and illustrative; the exact rights depend on the country, the contract and the type of land. "Limited" means the right exists with conditions. Read across: the mortgaged home-owner has most rights but not free ones, since the lender stands behind every sale. The ejidatario, a member of a Mexican ejido (see below), has strong use and inheritance rights but limited power to sell. None of the four holds exactly "ownership" in the layperson's sense, and every one holds something real. Possession and the clock: how a squatter can become an owner Possession, holding and using a thing as if it were yours, is the oldest evidence of ownership, and law treats it generously. Anyone who is in peaceful possession is protected against being dispossessed by force, even if they have no title, and with enough time possession can turn into ownership. The common law calls this adverse possession, the civil law usucapion (usucapión, prescription acquisitive). The reason is practical: records get lost, claims go stale, and a society needs someone to be the owner of the land that people have in fact been using for decades. The time required depends on the country and on whether you started in good faith. In England and Wales, 12 years for unregistered land; for registered land (Land Registration Act 2002), after 10 years the squatter may apply, the registered owner is notified, and an objection usually stops the claim. France requires 30 years, or 10 with a just title and good faith. Argentina's 2015 code: 10 years with good faith and a just title, otherwise 20. Chile: 5 and 10. Mexico, as commonly stated: 5 and 10. In the US each state sets its own rule, from about five to forty years. All demand that the possession be open and continuous, and in the common law "hostile", meaning without the owner's permission. Interactive · The possession clock Years of possession Started in good faith with a flawed deed Simply took over, no title Simplified teaching data; each also needs other conditions (public, peaceful, continuous, and so on). Mexico and Argentina's rules vary by state and code, and the US varies by state. Not a guide to anyone's claim. At 11 years the starting settings show how the systems part: England's unregistered rule has not yet run (12), France needs 10 if the possessor had a flawed deed in good faith and so can claim, Argentina's short period (10) has passed, and so have Chile's and Mexico's (5). Change to "no title" and most need many more years. Registers: who owns it when the paper lies? How can a buyer know the seller owns the land? There are two basic answers. In a deeds system, the buyer follows the chain of past transfers (the US keeps public records of deeds, and buyers rely on title searches and title insurance). The rule is the old Roman one, nemo dat quod non habet ("no one gives what they do not have"): a forged deed passes nothing, however many honest buyers come after. In a title register, the state keeps a register that says who owns each plot, and the register itself creates the right. Germany's Grundbuch is the model: ownership transfers when the new owner is entered (BGB §873), and under §892 a good-faith buyer can rely on the register even if it is wrong, unless an objection is recorded or the buyer knows it's wrong. Sir Robert Torrens introduced the same idea to South Australia with the Real Property Act 1858, and the "Torrens system" spread across Australia, New Zealand, much of Canada, Ireland, Singapore and beyond. England and Wales moved to a state register over the twentieth century, and the Land Registration Act 2002 extended it. France, by contrast, records deeds through a notary system (publicité foncière) but does not guarantee title, apart from Alsace-Moselle, which kept its German-era land register. In Chile the Conservador de Bienes Raíces is where an inscription transfers real-estate ownership; the property registries of Spain and Mexico record and protect rights. The tension is this: the more the register is protected, the safer a buyer is, and the more the true owner is at risk if someone forges. Take the classic case. Alice owns a house. Mallory forges a deed giving it to Bob, who is entered on the register. Bob sells to Carol. Who owns it? Interactive · The forged deed Deeds system (US-style) German Grundbuch Torrens register Carol bought in good faith Carol knew about the forgery No warning on the register Alice had recorded a warning A simplified summary of the general rule in each system; real statutes have more exceptions and the Torrens jurisdictions differ (the cited Frazer v Walker is a 1967 Privy Council decision on a New Zealand case). The commons: when everyone's property is no one's In 1968 the ecologist Garrett Hardin published "The Tragedy of the Commons" in Science. Picture a pasture open to all herders. Each herder gains the whole benefit of adding one more cow but shares the cost of overgrazing with everyone else. So each adds a cow, and together they destroy the pasture. Hardin's conclusion was that open access leads to ruin unless resources are privatised or governed by the state. Elinor Ostrom's life's work, Governing the Commons (1990), and her 2009 Nobel prize in economics, showed the argument leaves out a third path. Real commons are rarely open to everyone; they have defined boundaries and members. Communities from the Swiss Alps to Japanese forests and Spanish irrigation huertas have run commons for centuries with their own monitoring and penalties. The conditions that help: clear boundaries, rules that fit local conditions, a say for users in making rules, monitoring, graduated sanctions, and a recognised right to organise. Hardin himself later said he should have called it the tragedy of the unmanaged commons. The lesson for law: "private vs public" is a false choice, and the third option, community property, needs the legal system to recognise it. The model is simple. Suppose each cow yields 100 minus the number of cows (the pasture thins as it fills) and costs 20 to keep. The profit per cow is then 80 − N, and the total is N × (80 − N). Interactive · The shared pasture Cows on the pasture (N) Open access: herders keep adding Managed: one owner or agreed quotas A stylised model with invented numbers (yield 100 − N per cow, cost 20 per cow), in the spirit of Hardin's example. It shows incentives, not any real pasture. The total profit peaks at 40 cows, at 1,600. Open access pushes the herd to 80, where the profit is zero: every herder works for nothing. At 40 cows, the private gain from adding the 41st is still positive (39) while the gain to the group is negative (−1): the temptation is built in. Rules, or an owner, remove it. Intellectual property: ownership of ideas, with an expiry date Property in things that can be copied is a modern invention, and a bargain. A copyright protects an author's expression (not the idea) and, under the Berne Convention (1886), lasts at least for the author's life plus 50 years. Most of the world has lengthened this: the EU, Argentina, Brazil and Chile use life plus 70; Colombia 80; Mexico 100 for works still protected when its term was extended in 2003; India 60; China 50. A patent gives a monopoly on a new invention, normally for 20 years from filing (TRIPS, 1994), in exchange for publishing it. Trademarks protect names and logos and can be renewed for ever while used. The deal is a trade: society grants a temporary monopoly to reward creators, then the work joins the public domain. How long the term should be is a live argument: critics say extending terms, as the US did in 1998, rewards no new creation, while defenders point to longer lives and the wish to match trading partners. Interactive · When does it become free? The author died in Illustrative: each current term counted from the author's death, with copyright ending at the end of the calendar year. Real answers depend on the work, when it was published, transition rules when terms were extended, and corporate or anonymous authorship. In the US, works published before 1931 are already in the public domain (as of 2026), by a separate 95-year rule. For an author who died in 1980, the term is over in the EU, Argentina, Brazil and Chile at the end of 2050 (free from 2051), in Mexico at the end of 2080 (free from 2081). That is the difference between a one-line law and a century. Indigenous and communal land: ownership that isn't one person's Much of the world's land is held neither by a private owner nor by the state but by a community. In Mexico the ejido and the indigenous comunidad are the clearest example. After the Revolution, the 1917 Constitution (art. 27) allowed the redistribution of large estates to peasant communities, and the programme grew under President Cárdenas from 1934. The land belongs to the community, and its members, ejidatarios, hold rights to use their parcel and to pass it on. Selling was restricted until 1992, when art. 27 was amended to allow ejido land to be privatised under conditions, together with a new Agrarian Law and a titling programme (PROCEDE). Official figures from the National Agrarian Registry put social property (ejidos and agrarian communities) at around half of Mexico's territory, about 100 million hectares of 196 million (about 50.7%, the registry's 2017 count). The 1992 reform is still argued about: its supporters said titles would let farmers borrow and invest, critics said it opened the door to land sales and rural dispossession. Elsewhere the same question arises under different names. Colombia's constitution recognises collective resguardos; Brazil's 1988 Constitution recognises indigenous peoples' original rights to the lands they traditionally occupy, and the "marco temporal" dispute over whether only land occupied in October 1988 counts is still moving through the courts and the legislature. The Inter-American Court of Human Rights held in Awas Tingni v Nicaragua (2001) that communal indigenous property is protected as property. In Australia, Mabo v Queensland (No 2) (1992) rejected the idea that the continent was terra nullius and recognised native title, and Canada's Supreme Court made the first declaration of Aboriginal title in Tsilhqot'in Nation v British Columbia (2014). The UN Declaration on the Rights of Indigenous Peoples (2007) states the principle. Does formal titling help the poor? The Peruvian economist Hernando de Soto argued in The Mystery of Capital (2000) that giving informal holders legal title unlocks capital, because a house with a title can be mortgaged. Others found it is not so simple: a study of squatters in Buenos Aires by Galiani and Schargrodsky found titling raised investment in housing but did not increase access to credit. The honest summary is that titles help, but not by themselves. What a graduate just sees "Ownership" is a bundle: possess, use, exclude, lease, sell, bequeath, mortgage. Ask which sticks someone really holds. Every property system balances the owner against the public: "property entails obligations." Long, open possession can create ownership, because societies would rather settle who owns land than leave it open for ever. A register trades the safety of buyers against the safety of true owners; ask what it protects. Open-access resources decay, but the cure isn't only privatisation or the state: communities with boundaries and rules can manage a commons. Intellectual property is a time-limited deal, and the length of the time is a political choice that differs by country. A large share of the world's land is communal or customary, and law has had to learn to recognise it. Where it shows up next Constitutional Law (35/03): property clauses, such as the compensation owed when the state takes land, are among the oldest constitutional rights. Administrative Law (35/09): zoning, planning permission and expropriation are the daily contacts between owners and the state. International Law & Human Rights (35/10): indigenous land rights, and the treaties (Berne, TRIPS) that fix intellectual-property terms. The real world: a mortgage and a title search, a tenant's deposit, an app's licence terms, a village's forest rules, and the date a song enters the public domain. If you want to go deeper 📘 Textbook. Jesse Dukeminier, James Krier, Gregory Alexander and Michael Schill, Property (Aspen/Wolters Kluwer), the standard US casebook. 📘 Textbook. Kevin Gray and Susan Francis Gray, Elements of Land Law (Oxford University Press), the standard English text. 📘 Gentler. Elinor Ostrom, Governing the Commons: The Evolution of Institutions for Collective Action (Cambridge University Press, 1990), written for a general academic reader and full of real cases. 🎧 Free talk. Ostrom's 2009 Nobel lecture, "Beyond Markets and States", on the Nobel Prize site. 🌐 Free reference. The Cornell Legal Information Institute's Wex entry on property. The takeaway Property is not one thing but a bundle of rights, held with duties, proved by paper or a register, and ripened by time. Resources held by no one decay; the cure is rules, whether private, state or communal. Ideas are held for a limited term; peoples hold land in common. Every system is a choice about who bears the risk of a mistake. Try this: this week, take something you "own" (a flat, a phone, a bike) and list which sticks of the bundle you really hold: who could stop you selling, lending, or changing it? Then check how long a song you like stays protected where you live. Sources & Further Reading Sources. Honoré, "Ownership" in Guest (ed.), Oxford Essays in Jurisprudence (1961). French Code civil art. 544; BGB §§873, 892, 903 (gesetze-im-internet.de); Grundgesetz art. 14(2); Mexican Constitution art. 27 (1917; amended 1992). Hardin, "The Tragedy of the Commons", Science 162 (1968); Ostrom, Governing the Commons (1990) and 2009 Nobel Prize in Economic Sciences. Torrens: Real Property Act 1858 (South Australia); Frazer v Walker [1967] 1 AC 569 (PC). Possession periods: Land Registration Act 2002 sch. 6 and Limitation Act 1980 for England; the civil codes of France, Argentina (2015), Chile and Mexico, as summarised in secondary sources (Wikipedia, "Adverse possession"), so check the code of your own country; US states vary from about five to forty years. Copyright terms: Berne Convention (1886); the national terms are from secondary summaries (Wikipedia, "List of countries' copyright length"); TRIPS art. 33 (20 years). Mexico: 100 years for works protected on or after 23 July 2003. Ejido share: Registro Agrario Nacional, 2017 (99,714,952 ha, 50.7% of 196,437,500 ha); later official counts give about 51%. Mabo (No 2) (1992) 175 CLR 1; Awas Tingni v Nicaragua (IACtHR 2001); Tsilhqot'in Nation v BC 2014 SCC 44; UNDRIP (2007). De Soto, The Mystery of Capital (2000); Galiani & Schargrodsky, "Property rights for the poor", Journal of Public Economics (2010). Interactive numbers computed in node. This describes how legal systems work; it is not legal advice. 📘 Dukeminier et al., Property 📘 Ostrom, Governing the Commons 🎧 Ostrom's Nobel lecture 🌐 Cornell LII Wex: Property Step 8. Civil Procedure & Evidence: How a Dispute Becomes a Case, and What Counts as Proof ------------------------------------------------------------------------------------------ Why: How a dispute becomes a trial, and what counts as proof. The rules that decide who can sue whom, where, how the facts are found and how sure a judge must be are as important as the rules of right and wrong themselves. Two neighbours fall out over a fence. One says the other built it three metres onto her land. The other says the surveyor drew the line wrong in 1998. Each is certain. In the story that matters, though, neither is a lawyer yet, and the real question is not who is right. It is: what has to happen before anyone with power will decide? Someone has to be given the dispute. Both sides have to be heard. Somebody has to find out what the land records say. And at the end, a judge must be convinced, to some degree, that one account is the better one. That chain of steps is civil procedure, and the rules about what the judge may look at and how much it must believe are evidence. Law students sometimes find them the dullest part of the degree. Practising lawyers know that most cases are won or lost inside them. This describes how legal systems work and isn't legal advice. Procedure differs by country, court and kind of case, and it changes. For a real dispute, ask a qualified lawyer or your local court's self-help service. The course in one box Who takes itLaw students everywhere. The US first-year core has a full Civil Procedure course (with Evidence usually an upper-level course); in the five-year degrees of Spain, Mexico, Argentina and Chile, and in Germany's state-exam subjects, procedural law is taught as its own subject beside the substantive private law. What it is forTurning a private quarrel into a decision that a court will enforce, fairly and in finite time. Comes afterLegal Reasoning & Writing (35/02). Leads toEverything that ends in a court: Contracts & Obligations (35/04) and Torts & Civil Liability (35/05) say who should win, and this subject says how that gets decided. It also connects to Game Theory (34/45), the maths of settlement. What this piece gives youYou won't be able to file a claim. You will understand why discovery is a US habit that most of the world avoids, what "balance of probabilities" does and does not mean, and why most disputes never reach a judgment. An easier first read: How Government Actually Works (18/01). This piece goes further into the courtroom. The common ground: a referee for private quarrels Every society must give people a way to settle disputes other than force. The answer is the same everywhere: a neutral third party with power to decide and enforce. Then every system has to answer four questions. Who may bring a case and in which court? How are the facts found? How sure must the decider be? And how are the costs shared, since a system that no one can afford is no remedy at all? FamilyWho drives the caseHow facts are found United StatesThe parties. The Federal Rules of Civil Procedure (1938) govern federal courts; each state has its own rules.Broad pre-trial discovery by the parties; a jury is available in many civil cases (Seventh Amendment in federal court). England and WalesThe parties, supervised by judges using the Civil Procedure Rules (1998).Disclosure of documents; mostly judge-alone trials today. Latin America (Mexico, Argentina, Brazil, Chile, Colombia)The judge directs the process under a national code; recent reforms have added oral hearings.Written claim and defence, then the judge orders the evidence. Colombia's General Procedure Code (2012) and Brazil's Civil Procedure Code (2015) are modern examples. Continental Europe (France, Germany, Spain; EU rules for cross-border cases)The judge manages the case; parties still present arguments and name evidence.The judge decides what evidence is needed. Parties produce their own documents; there is no US-style fishing for the other side's papers. Notice what is shared: written pleadings, a right to be heard, and a reasoned judgment. The differences are about who does the digging and how much. How a dispute becomes a case Courts cannot decide everything. A claim gets in the door through jurisdiction, which has two faces: the power to hear this kind of dispute, and the power over this defendant. In the US, the Supreme Court's 1945 decision in International Shoe v. Washington said a state may hear a case against an out-of-state defendant who has "minimum contacts" with it. In the EU, the Brussels I Recast Regulation (1215/2012) takes a plainer default: sue the defendant in the courts of the country where they are domiciled, with listed exceptions such as contract performance. Civil-law countries generally follow some form of that domicile rule. The claim must then be written down. In the US, a complaint must state facts that make the claim plausible, a standard fixed by Bell Atlantic v. Twombly (2007) and Ashcroft v. Iqbal (2009); a defendant can ask the judge to dismiss a claim that fails it. Civil-law systems also begin with a written claim, but the judge's focus is whether the claim fits a rule in the code. Interactive · From quarrel to judgment US federal-style Civil-law style (code, judge-led) Step A general outline of an ordinary first-instance civil case. Real procedure varies by court, claim size and country (small claims, family and commercial courts follow their own paths). Discovery or judge-led fact-finding: who does the digging? The sharpest difference in the world's civil procedure is who finds the evidence. In the United States, after the complaint, each side may demand documents, written answers, and sworn testimony from the other side and from outsiders (depositions). The idea is that if both sides see everything before trial, cases settle on their merits and "trial by ambush" ends. Since December 2015 the federal rules limit discovery to what is "proportional to the needs of the case", because it was being used as a weapon: whoever can afford to bury the other in requests can force a settlement. England and Wales has "disclosure", narrower and supervised by the judge from the start. Most of continental Europe and Latin America see US discovery as a private investigation conducted outside a judge's view; the party who relies on a fact must name and produce the evidence, and the judge may order specific documents, but not a general search of the other side's files. This clash is real: American court orders for evidence abroad regularly meet resistance from foreign courts and data-protection law. Interactive · Who digs, and what it costs United States England and Wales France / Germany Latin American codes Documents to review Documents a reviewer reads per hour Cost per reviewer hour Cost = documents ÷ speed × hourly rate, with a single pass and no technology-assisted filtering. Illustrative figures, not a quotation. Real projects use software to cut the pile first. With the defaults, half a million documents at 60 an hour is about 8,300 hours of reading, or roughly $830,000 at $100 an hour. That is why a threat of discovery can force a settlement, and why proportionality limits exist. Burdens and standards of proof Evidence settles facts, but never perfectly, so the law uses two dials. The burden of proof says who loses if the evidence is balanced: the person who asserts the fact. The standard of proof says how sure the judge must be. In US civil cases the usual standard is "preponderance of the evidence"; in England and Wales, the "balance of probabilities". Both mean, informally, "more likely than not". Some civil claims, like fraud allegations in some states or removing a parent's rights, need "clear and convincing evidence". In criminal cases the standard is higher: "beyond reasonable doubt", which the US Supreme Court held to be constitutionally required in In re Winship (1970). English judges tell juries to be "sure". In France and many civil-law systems, criminal and civil judges decide according to intime conviction ("inner conviction"): the judges are asked to examine, in good conscience, what the evidence has done to their own reason, without a numerical test. German civil courts likewise evaluate evidence freely rather than counting it. Reformed criminal codes in Latin America have imported the language of "beyond reasonable doubt" (más allá de toda duda razonable). Courts almost never attach percentages to these standards; the thresholds below are rough illustrations only, and studies of judges and jurors give a wide range. Interactive · How sure is "sure enough"? How likely the claim seems, after the evidence Thresholds are illustrative: more likely than not = just over 50%; clear and convincing, drawn at 75%; beyond reasonable doubt, drawn at 95%. Judges do not use numbers, and intime conviction has none. Informal pictures of the dials, not rules. The dial means a 60% claim wins a civil case and loses a criminal one. It also means the claimant who has the burden loses at exactly 50-50: the system accepts that error on purpose, to force a choice. Hearsay: why "I heard that…" is treated with suspicion In the US, the hearsay rule excludes an out-of-court statement offered to prove that what it says is true (Federal Rule of Evidence 801(c)). The reason is practical: the speaker was not under oath, the jury cannot watch them, and the other side cannot cross-examine. The rule is full of exceptions (Rules 803 and 804 list excited utterances, business records and others) and exclusions (for example, a party's own statements used against that party). England and Wales largely abandoned it in civil cases in the Civil Evidence Act 1995, leaving hearsay to be judged on weight. Civil-law courts have no equivalent rule, because a professional judge, not a jury, is assumed able to discount weak evidence, but they prefer witnesses heard directly. In criminal cases across Europe, Article 6(3)(d) of the European Convention gives the accused a right to examine witnesses against them. Interactive · Predict, then reveal Statement Hearsay problem Not a hearsay problem Simplified examples in the style of the US Federal Rules of Evidence. Whether a statement is excluded depends on the exact facts and local rules. Settling, arbitrating, mediating, and getting to court at all Most civil disputes never reach a judgment. Parties settle because trial is slow, costly and risky, and the rules about costs matter: in the US each side usually pays its own lawyer (the "American rule"), while in England and Wales and many civil-law countries the loser pays a share of the winner's costs. Two other routes leave the courts altogether. Arbitration hands the decision to a private decider the parties choose. It has enforcement behind it through the New York Convention of 1958, which about 172 states had joined as of January 2023, so an award made in one can be enforced in the others. Mediation keeps the decision with the parties, with a neutral helping them to find a deal. Brazil's 2015 code places a conciliation or mediation hearing early in ordinary cases; many systems encourage or require some attempt at it first. Interactive · To sue or to settle? Each side pays its own Loser pays costs Amount claimed Chance of winning Legal costs for each side Settlement offer Assumes both sides spend the same costs, the winner recovers its costs in full under "loser pays" (real recovery is partial), and the defendant can pay. Illustrative money, not advice. With the defaults, a claimant expects $30,000 from going to court under the American rule and $36,000 under loser-pays. An offer of $35,000 is therefore worth taking in the first system and not in the second. The rule, not the facts, changed the answer. There is also the question of who can reach a court at all. The World Justice Project estimates that about 5.1 billion people, roughly two-thirds of the world, lack meaningful access to justice. In the US, the Legal Services Corporation's 2022 report found that low-income Americans got no or too little legal help for 92% of the problems that substantially affected them in the past year. The scholars Mauro Cappelletti and Bryant Garth, in the Florence Access-to-Justice Project (1978), described three "waves" of reform: legal aid for the poor, procedures for group and public interests, and simpler, cheaper processes including mediation. The US Constitution guarantees a lawyer to a poor person charged with a crime (Gideon v. Wainwright, 1963) but, in general, not in a civil case (in Lassiter v. Department of Social Services, 1981, the Court held there is no automatic right to a lawyer even when a parent may lose a child). What a graduate just sees Every dispute passes through the same gates: who can sue, where, and with what facts. Who digs for evidence, the parties or the judge, is the biggest difference between legal families. A burden says who loses a tie; a standard says how sure the judge must be. "More likely than not" is a rough dial, not a number a judge computes. Hearsay rules are about reliability and cross-examination, and many systems manage without them. Whether the loser pays costs changes which cases get filed and settled. A right with no affordable way to enforce it is a promise, not a right. Where it shows up next Contracts & Obligations (35/04) and Torts & Civil Liability (35/05): every rule there is only as strong as the process that enforces it. Game Theory (34/45): settlement bargaining is a game in which each side's offer depends on its guess of the other's. International Law & Human Rights (35/10): the right to a fair hearing in Article 6 of the European Convention applies to civil disputes too. In the world: a landlord-tenant hearing, an international company choosing arbitration, a legal-aid clinic, a court that moves to oral hearings after a reform. If you want to go deeper Standard textbooks: Stephen Yeazell and co-authors, Civil Procedure (a standard US casebook); Mueller and Kirkpatrick, Evidence (US). For the English system, Adrian Zuckerman, Zuckerman on Civil Procedure. Check for current editions. Comparative: Mirjan Damaška, Evidence Law Adrift (1997), on why common-law and continental systems treat evidence differently. Gentler: Jonathan Harr, A Civil Action (1995), a true story of a toxic-water lawsuit that shows discovery, burden of proof and settlement pressure at work. Free course: the Open University's OpenLearn unit Judicial decision making, adapted from its civil justice and tort law module. The takeaway Before a court can say who is right, it must decide who can sue, where, on what facts, with what proof and at what cost. Systems agree on the problem, a neutral referee, and disagree on who gathers evidence, how sure the judge must be and who pays. Most disputes never reach judgment, and the price of reaching one decides who even tries. Try this: next time you read about a lawsuit, ask who has to prove what, how sure the court must be, and whether the loser pays. You can often guess the likely outcome, and the likely settlement, from those three answers. Sources & Further Reading Sources. Federal Rules of Civil Procedure (1938; proportionality amendment effective 1 December 2015, per the discovery summary); International Shoe Co. v. Washington, 326 U.S. 310 (1945); Bell Atlantic v. Twombly (2007) and Ashcroft v. Iqbal (2009); Regulation (EU) 1215/2012; In re Winship, 397 U.S. 358 (1970); Civil Evidence Act 1995; Federal Rule of Evidence 801 and Rules 803-804; Article 6(3)(d) ECHR; New York Convention 1958 (172 parties as of January 2023, per its Wikipedia summary); World Justice Project estimate of 5.1 billion (as summarised on Wikipedia, "Access to justice"); Legal Services Corporation, The Justice Gap (2022); Cappelletti and Garth (1978); Gideon v. Wainwright (1963); Lassiter (1981). Details of Latin American codes (Colombia 2012, Brazil 2015) are general descriptions of the reforms, not article-level citations. 🌐 OpenLearn: Judicial decision making 📘 Yeazell and co-authors, Civil Procedure 📘 Harr, A Civil Action 📘 Damaška, Evidence Law Adrift Step 9. Political Theory: Justice, Power, Legitimacy and Liberty ---------------------------------------------------------------- Why: Justice, legitimacy and why law binds at all. Four questions every society answers whether it knows it or not: who rules, why anyone obeys, how free people should be, and what a fair share looks like. Thinkers from Athens, Qufu, Pataliputra and Tunis gave different answers, and each is still in use. select{font-family:-apple-system,sans-serif;font-size:.9rem;min-height:44px;max-width:100%;min-width:0;border:1px solid var(--line);border-radius:10px;background:var(--hi);color:var(--ink);padding:6px 8px} .row{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:6px 0} .row>*{min-width:0} .chips button{min-width:0} A traffic light turns red at 3 a.m. on an empty street, and you stop. Nobody is watching. Why? Because it is the law, because it is sensible, because everyone else stops, because someone could be coming. Now scale that up: why do millions of people hand over a slice of their pay every year, accept a verdict from a stranger in a robe, or send their sons and daughters to fight when an official signs a paper? Political theory is the study of that ordinary miracle, and of whether it is justified. It is not the same as political science that counts votes. It asks what a government is for, when it has the right to command, and what we owe each other. The strongest answers come from every continent, and a good course reads them side by side rather than treating Europe as the default. The course in one box Who takes itPolitical science, philosophy and law students, usually in year 1 or 2. It is the opening course of Oxford's PPE politics paper, MIT's Course 17 and Sciences Po, and the heart of Oxford's Jurisprudence. English majors meet the same ideas in novels. What it is forGiving you the concepts to say why a law, a tax or a regime is fair or unfair, rather than only that you like it. Comes afterNothing. It is the starting point. Leads toComparative Politics (35/13), and for law students Constitutional Law (35/03) and International Law & Human Rights (35/10). The ideas here also feed Political Economy (35/17). What this piece gives youYou will not settle the debates; nobody has. You will recognise six big answers, who gave them and what each one's critics say. It takes no side on today's partisan fights. Easier first reads: The Social Contract: Why Obey a State at All? (18/14), What Is Freedom? (18/11) and Justice: From Plato to Rawls, Nozick and Sen (05/13). This piece goes further and lets you test the arguments. Why have a state at all? Nature, contract and the fish Start from a thought experiment: no government. What would life be like? Thomas Hobbes, writing during the English civil war, said in Leviathan (1651) it would be a "war of all against all", with life "solitary, poor, nasty, brutish, and short". Not because people are wicked, but because they fear each other, and the safest move against a fearful neighbour is to strike first. The only escape is to give up your freedom to a sovereign strong enough to keep everyone in awe. The same worry appears elsewhere. The Indian tradition of statecraft speaks of matsya-nyaya, "the law of the fishes", where the big fish eat the small. Kautilya's Arthashastra (attributed to the Mauryan minister of about 300 BCE; Patrick Olivelle's 2013 translation argues the text took its present shape around the first century CE from older material) makes the king, and his rod of punishment, the cure. Ibn Khaldun, in the Muqaddimah (1377), argued that people need a restraining authority because aggression is natural to them. Aristotle in his Politics disagreed in a different way: humans are by nature political animals who flourish only in a community, so the state is not an invention but a fulfilment. The social contract tradition says a state is justified by an agreement, real or imagined. John Locke (Second Treatise, 1689) thought people in nature already have rights to life, liberty and property, and form governments to protect them, so a government that violates them may be resisted. Jean-Jacques Rousseau (The Social Contract, 1762), opening with "Man is born free, and everywhere he is in chains", argued legitimacy comes only from the general will of the people governing themselves. Hobbes wanted a strong sovereign; Locke a limited one; Rousseau a self-governing one. Hobbes's logic is a game you can run. Each person chooses to keep the peace or to grab. If everyone keeps the peace each gets 3; a grabber facing a peaceful person takes 4 and leaves them 0; two grabbers fight and each get 1. Grabbing wins in every pairing, so peace collapses. Now add a sovereign who punishes grabbers. How much punishment is enough? Interactive · Hobbes's trap Penalty on a caught grabber Chance a grab is caught Share keeping the peace at the start Payoffs: peace–peace 3 each; grab vs peaceful 4 and 0; grab–grab 1 each. Expected penalty = penalty × chance. Strategies spread in proportion to their advantage (a replicator model, 200 rounds). A toy: it ignores the cost of the sovereign, and who watches the watcher. The answer is neat: an expected penalty above 1 is enough, whatever the starting mix, because it removes the temptation exactly. But notice what the toy leaves out. Who punishes the sovereign? That is Locke's question, and the reason constitutions limit power. Who should rule, and for whose sake? Plato's Republic (about 375 BCE) answered: those who know. Rule should belong to philosopher-guardians trained to see the good, as a ship should be steered by a navigator, not by a vote of the crew. Aristotle's Politics asked two more practical questions of every regime. How many rule: one, few or many? And for whose benefit: the common good, or the rulers' own? Combine them and you get six constitutions, three good and three corrupted. Interactive · Aristotle's six regimes One rules A few rule The many rule For everyone's good For the rulers' own gain Aristotle, Politics III. His term for rule of the many in their own interest is "democracy", which he saw as rule of the poor majority; "polity" is his name for the good form of rule by the many. Notice the question under Aristotle's grid: not "who is in charge?" but "is power used for everyone?" Other traditions ask the same. Confucius (551 to 479 BCE) held that government begins with the ruler's own conduct; a leader who is himself upright needs few orders. Mencius, his follower, said the people matter most, the state next, the ruler least, and that a ruler who abuses the people loses the Heaven-given mandate to rule, an idea that justified rebellion in Chinese history. Kautilya's king serves the welfare of his subjects, whose happiness is his, though the Arthashastra is frank about spies, deception and war in a way that Confucian texts avoid. Machiavelli, centuries later, separates what rulers should be from what they must do to keep power. Each of these is a view about the same two variables. Why people obey: power, legitimacy and the tipping point Power is the ability to make others do things. Legitimacy is the belief that the power is rightful. Max Weber, in lectures of 1919 (Politics as a Vocation), defined the state as the body that claims the monopoly of legitimate force within a territory, and gave three sources of legitimacy: tradition ("it has always been so"), charisma (a leader's personal appeal) and legal-rational rules (offices and procedures). Ibn Khaldun added a cycle: a dynasty rises on asabiyya, the solidarity of a tight group, then its rulers grow comfortable, solidarity fades, and after about three generations, which he counted as roughly 120 years, a hardier group replaces it. Legitimacy is not only a feeling. It works as a prediction about everyone else. Mark Granovetter's threshold model (1978) says each person has a threshold: they will join a protest if enough others already have. Some people join first at nothing; some join at ten others; some need half the street. Whether a crowd tips depends on the whole distribution, not the average. The economist Timur Kuran used this idea to explain why East Germany's regime seemed stable until the autumn of 1989 and then fell. Interactive · Who joins the crowd? Thresholds 0, 1, 2 ... 99 Same, but the "1" needs 2 Bell-shaped (use sliders) Average threshold Spread of thresholds 100 people. Each joins when the number already in the crowd reaches their threshold. The first mode is Granovetter's own example: nudging one person's threshold from 1 to 2 turns a full riot (100) into a crowd of one. Bell-shaped thresholds are spaced by the normal distribution. A model, not a forecast. The moral of the model is that a regime's support can be much thinner than it looks, and also that a crowd's size can hide how fragile it is. Legitimacy lives in expectations about other people, which is why regimes work hard at appearing strong, and why sudden changes surprise even the people living through them. Liberty: where does my freedom end? John Stuart Mill's On Liberty (1859) gave the most famous rule: the only purpose for which power can rightfully be used against a member of a community, against their will, is to prevent harm to others. Their own good, physical or moral, is not a sufficient warrant. This is the harm principle. Isaiah Berlin (1958) sorted freedom into negative liberty (freedom from interference) and positive liberty (the capacity to run your own life), warning that talk of the "real self" can excuse tyranny. Philip Pettit and the republican tradition, from Rome to Madison, defined freedom as non-domination: you are unfree if someone merely can interfere at will, even if they are kind. Confucian thought sees the person as made by relationships and duties, so freedom detached from role and community seems thin. Nozick treats each person as the owner of their body and property. These lenses give different answers to concrete questions. Choose a case below. The answers are how a thinker in each tradition would typically reason, our extrapolation, not quotations. Interactive · Five lenses on one law Case Lenses: Mill (harm principle), Nozick (self-ownership and property), Rawls (equal basic liberties, fair terms), Confucian (roles, virtue and harmony), republican (freedom as non-domination, after Pettit). Each lens is a family of views, with internal disagreements. The point is not to find the winning lens but to see that people who agree on "freedom is important" can disagree on a helmet law for honest reasons: they are counting different things. Justice: the veil, the entitlement and the flute John Rawls (A Theory of Justice, 1971) asked what rules we would choose for society if we did not know our place in it: rich or poor, clever or slow, man or woman, believer or not. Behind this veil of ignorance, he argued, we would choose equal basic liberties and allow inequalities only if they work to the benefit of the least advantaged: the difference principle. He thought a cautious chooser would follow the "maximin" rule, maximising the worst outcome. John Harsanyi replied that a rational chooser would maximise the average instead. The truth may lie between, and your own fear of the bottom sets where. Interactive · Behind the veil Four invented societies, each with five income groups (thousands per year). You will be placed in one group at random. How much you fear landing at the bottom Average only (Harsanyi) Worst case (maximin) Incomes are illustrative. "Equal-share value" is the sure income you would swap for the gamble, using constant-risk-aversion utility: fear 0 is the plain average, 1 is the geometric mean (log utility), 10 or more is treated as the pure minimum. Robert Nozick, in Anarchy, State, and Utopia (1974), objected from another direction. Justice is not a pattern of shares but a history of how they came about: if holdings were acquired fairly and transferred freely, the result is just, whatever it looks like. His example: start from any distribution you like, and suppose a million fans each freely pay 25 cents to watch the basketball star Wilt Chamberlain play. He ends up rich. To keep the pattern you would have to keep stopping free exchanges. Critics replied that markets rest on rules the community sets (Rawls's "background justice"), and that G. A. Cohen argued the freedom of the poor is also reduced by the property system. Interactive · Wilt Chamberlain in a village Fans who pay Each fan's payment (out of 100 coins) A village of 100 people, each starting with 100 coins (perfect equality, Gini 0). The Gini coefficient runs from 0 (equal) to 1 (one person has all). Amartya Sen (The Idea of Justice, 2009) came at it from a third angle. We do not need a perfect blueprint of a just society to know that famine or slavery is unjust; we need ways to compare real options. He asks what people are actually able to do and be (their capabilities), not only what they own. His example: three children quarrel over a flute. The first can play it, the second is poor and has no toys, the third made it. A utilitarian, an egalitarian and a libertarian each have a good reason to pick a different child, and none is simply wrong. Sen's moral is that plural, reasoned argument matters more than a single formula. Whose voices were left out of the contract? Great theories have blind spots, and some of the best political theory is the critique of the blind spots. Mary Wollstonecraft's A Vindication of the Rights of Woman (1792) argued that women's supposed unfitness for citizenship was produced by an education built to make them pleasing instead of rational, so the argument for equal rights applied to them too. Mill's The Subjection of Women (1869) made the same case from liberal premises. Karl Marx and Friedrich Engels (Communist Manifesto, 1848) argued that the question "what is a fair contract?" hides that workers must sell their labour to survive, so political equality can coexist with deep economic unfreedom; defenders of markets reply that Marx's predictions failed and that voluntary exchange raises the poorest. (31 Political Economy covers that debate.) Carole Pateman (The Sexual Contract, 1988) and Susan Moller Okin (Justice, Gender, and the Family, 1989) asked why theories of justice rarely examined the household. Charles Mills (The Racial Contract, 1997) argued that the social contract was in practice a contract among whites that excluded others. Communitarians such as Michael Sandel (Liberalism and the Limits of Justice, 1982) said Rawls's chooser, stripped of identity, is not a real person. Gandhi's Hind Swaraj (1909) questioned whether modern states, even self-governing ones, deliver freedom. These challenges did not end the older traditions, which have replies; they widened the conversation about who counts. What a graduate just sees Every government answers four questions (who rules, why we obey, how free, how fair), whether it says so or not. A state can be justified as nature's fulfilment (Aristotle), a bargain (Hobbes, Locke), a general will (Rousseau), or a protector (Kautilya). Each carries a different limit on power. Ask "how many rule, and for whom?" before arguing about names. Aristotle's two questions still sort most regimes. Legitimacy is a belief about what others believe. Regimes can look stable and be brittle, as in a threshold cascade. "Freedom" has at least three meanings (no interference, capacity, no domination), and people can honestly disagree while using the same word. Justice theories answer differently: a fair procedure (Rawls), a fair history (Nozick), or fair real options (Sen). Ask which one an argument is using. A thought experiment is a tool for isolating a variable, and its strength depends on what it assumes away. Who is left out of a theory is as informative as who is in it. Where it shows up next Comparative Politics (35/13): Aristotle's grid becomes the study of presidential and parliamentary systems, democracies and autocracies; Weber's legitimacy becomes the question of why some regimes last. Constitutional Law (35/03) and International Law & Human Rights (35/10): Locke's limits and Mill's harm principle live on in bills of rights and proportionality tests. Political Economy (35/17): Rawls, Nozick and Marx are the three poles of the argument about markets and fair shares. In the world and in books: every constitutional debate, every tax argument, and every novel about a tyrant or a rebellion. Literature students find these arguments in dystopias and in epics from the Mahabharata to Orwell. If you want to go deeper 📘 Textbook. Will Kymlicka, Contemporary Political Philosophy: An Introduction (Oxford, 2nd edition, 2002). The classic survey of utilitarianism, liberal equality, libertarianism, communitarianism, feminism and multiculturalism. 📘 Textbook. Adam Swift, Political Philosophy: A Beginners' Guide for Students and Politicians (Polity; later editions). Clear and problem-led. 📘 Gentler. Michael Sandel, Justice: What's the Right Thing to Do? (2009). Everyday dilemmas leading into the big theories. 🌐 Free course. Yale Open Courses, PLSC 114 Introduction to Political Philosophy (Steven B. Smith): Plato to Rawls, with lectures and transcripts. Also Sandel's Justice course from Harvard. The takeaway Political theory gives names to the questions every society answers: why a state, who should rule and for whom, why people obey, how free we should be, and what is fair. No single tradition has the last word, and the best answers have been argued across Athens, China, India, the Islamic world and modern Europe; the best critics asked who was left out. Try this: next time you hear an argument about a law, name what it assumes. Is it about harm to others, about fairness of procedure, about a fair history, or about what people can actually do? Then ask which of the other three it leaves out. Sources & Further Reading Sources. Primary texts are in the public domain: Plato's Republic, Aristotle's Politics (III), the Analects and Mencius, Hobbes's Leviathan (1651, ch. 13), Locke's Second Treatise (1689), Rousseau's Social Contract (1762), Wollstonecraft (1792), Marx and Engels (1848), Mill (On Liberty 1859; Subjection of Women 1869). Later works are described, not quoted: Weber (Politics as a Vocation, 1919), Berlin, "Two Concepts of Liberty" (1958), Rawls (1971), Nozick (1974), Pettit (1997), Sen (2009), Granovetter, "Threshold Models of Collective Behavior" (American Journal of Sociology, 1978), Kuran, "Now Out of Never" (World Politics, 1991), Pateman (1988), Okin (1989), Mills (1997), Sandel (1982). Arthashastra: Olivelle, King, Governance, and Law in Ancient India (Oxford, 2013), which dates the finished text to the early centuries CE; the traditional attribution to a Mauryan minister about 300 BCE is contested. Ibn Khaldun's dynastic cycle: Muqaddimah (1377), with the three-generation, 120-year figure as he gave it. Every number in the interactives was computed in node (the Hobbes toy, the threshold cascade, the equal-share values and the Gini coefficients); incomes and populations are invented for illustration. 🌐 Yale Open Courses: PLSC 114 Introduction to Political Philosophy 🌐 Harvard: Justice with Michael Sandel 📘 Kymlicka, Contemporary Political Philosophy Step 10. Administrative Law: How Government Is Held to the Law -------------------------------------------------------------- Why: How governments are held to the law. Most of what a state does to you is done by an official, not a legislature or a court. Administrative law is the set of rules that make the officials answer. A woman applies for a disability benefit and is refused in a two-line letter. A restaurant is shut by a health inspector the day before a holiday. A mining company is told its permit is cancelled. A journalist asks a ministry for the contract behind a new bridge and gets silence. None of these decisions came from a parliament or a judge. Each was made by an official acting under a law, and each can change a life. Modern governments do thousands of such things every day, because statutes are written in broad terms and someone must apply them to the individual case. So the question for lawyers is not whether officials may decide, but how they can be made to stay inside the law: what is the power, what is the procedure, who can challenge it, and who can look at the papers? That is administrative law. A graduate keeps seeing a pattern in every news story about an agency: power, limits, review. This describes how legal systems work and isn't legal advice. Laws, deadlines and courts differ by country and change. If a government decision affects you, check the time limits for appeal with a lawyer or advice service where you live. The course in one box Who takes itLaw students, usually in years 2 or 3 (in the US an upper-level elective or a required course; in the five-year degrees of Spain, Mexico, Argentina and Chile a standard public-law subject, often called derecho administrativo; in Germany Verwaltungsrecht in the state exams). Public-policy and political-science students often take a version of it. What it is forKeeping the power of officials lawful, reasoned, fair and open to challenge. Comes afterConstitutional Law (35/03). Leads toInternational Law & Human Rights (35/10), European Union Law (35/11) and Public Policy (35/16), since policy is carried out through administrative decisions. What this piece gives youYou won't be able to challenge a real decision. You will see the four ways a court can say an official went wrong, why deference is the hot argument, how proportionality works, and why one country sends the same complaint to a special court and another to the ordinary courts. Easier first reads: How Government Actually Works (18/01) and Rights, Constitutions and the Rule of Law (18/04). The common ground, and three ways to build the court The human problem is as old as rulers: someone with power makes decisions about people who cannot easily answer back. The common solution is the rule of law: officials may do only what a law lets them do, and a person affected can go to an independent body. A modern state also needs to keep its agencies expert and quick. All systems balance those two aims. Where they differ is who does the reviewing. Germany's Basic Law is blunt: "Should any person's rights be violated by public authority, he may have recourse to the courts" (Article 19(4)). Brazil's constitution is even more sweeping: the law may not exclude from review by the judiciary any injury or threat to a right (Article 5, XXXV). The question is which courts. FamilyWho reviews officialsDistinct features United StatesOrdinary federal courts, under the Administrative Procedure Act of 1946 and the Constitution.Courts set aside action that is "arbitrary and capricious" or beyond statutory power. Judicial review of government itself dates to Marbury v. Madison (1803). England and WalesThe Administrative Court and tribunals, by "judicial review".Largely developed through case law; reasonableness, fairness and legality; the Human Rights Act 1998 adds a rights-based layer. France and continental EuropeSeparate administrative courts, topped in France by the Conseil d'État; Germany has its own administrative court branch.A body of public-law rules distinct from private law; judges trained in public law. Latin AmericaMixed. Brazil and Argentina use the ordinary judiciary; Colombia has a Consejo de Estado at the top of a separate administrative jurisdiction; Mexico has a federal administrative tribunal alongside the amparo.The amparo (and Colombia's tutela) is a fast procedure to protect constitutional rights against officials and sometimes private actors. Seen from a distance the divide is between systems with one set of courts for everything and systems with a second court branch specialised in the state. Convergence is the story: European Union law, the European Convention on Human Rights and inter-American human-rights law have pushed every system toward similar standards. Four ways an official can go wrong When a court looks at a decision it does not usually ask "was this the best decision?", which would make the judge the official. It asks whether the decision was lawful. English law, in the House of Lords' GCHQ case (1985), grouped the grounds into illegality (acting beyond the power the law gives), irrationality (a decision so unreasonable that no reasonable authority could have made it, the old Wednesbury test of 1948) and procedural impropriety (unfair process). US law uses similar ideas: a decision can be "arbitrary and capricious" if the agency ignored an important factor or offered no reasoned explanation (Motor Vehicle Manufacturers v. State Farm, 1983). A fourth ground has spread across the world: proportionality, below. Procedure is its own ground. A person facing a decision should know the case against them, be able to answer it, and get reasons. The US Supreme Court's test in Mathews v. Eldridge (1976) weighs three things: the private interest, the risk that the procedure gets it wrong (and what extra safeguards would add), and the government's burden. The tool below checks your instincts. Interactive · Which ground is it? Case Illegality Irrationality Unfair procedure Disproportionate Invented examples. Real cases often raise several grounds at once, and the labels vary by country. Deference: who gets to read the statute? The hottest argument in the field is how much a court should defer. Agencies have expertise, accountability to elected leaders, and the day-to-day problems in front of them. Courts have independence and the job of saying what the law means. In the US the Chevron decision (1984) told courts that where a statute is ambiguous, they must accept the agency's reasonable reading. On 28 June 2024, in Loper Bright Enterprises v. Raimondo, the Supreme Court overruled Chevron (6 to 2; Justice Jackson took no part): courts must use their own judgment about what the statute means, giving an agency's view only the weaker respect that its persuasiveness earns (the Skidmore approach). Earlier decisions made under Chevron were not overturned. Supporters of Loper Bright say it returns the meaning of the law to judges and stops agencies enlarging their own power. Critics say it hands policy to judges and makes regulation slower and less expert. Other countries have their own mix: Many other courts leave expert and policy judgments to the agency while checking the legal framework. Interactive · A toy model of deference No deference Some weight (Skidmore-like) Strong deference (Chevron-like) The court's best reading of the law The agency's reading A toy: readings sit on a 0 to 10 line; the agency's reading is upheld if it lies within a window around the court's own (0 with no deference, 1 with some weight, 3 with strong deference). Real law has no such scale. It illustrates the mechanism only. Proportionality: the test most of the world uses When a measure limits a right, many legal systems ask four questions in order. Is the aim legitimate? Is the measure suitable, does it actually help? Is it necessary, is there a gentler way that works nearly as well? Is it proportionate in the narrow sense, do the benefits outweigh the harm to the right? The idea grew in German administrative courts in the late 19th century (the Prussian Higher Administrative Court limited police discretion this way) and was developed by the Federal Constitutional Court from the 1950s, famously in its 1958 Pharmacy decision. Canada adopted a version in R v. Oakes (1986), the Court of Justice of the EU and the European Court of Human Rights use it routinely, and constitutional courts in many countries, including Colombia and Brazil, use proportionality-style tests. The United States is the notable outlier: its constitutional doctrine mostly uses "tiers of scrutiny" (rational basis, intermediate, strict) rather than proportionality, though proportionality appears in Eighth Amendment cases on punishments. Defenders of proportionality say it forces reasoning into the open. Critics, including some of its own scholars, say the last step asks judges to weigh things that cannot be weighed, and that it can invite judges to substitute their values for the legislature's. Interactive · The four-step test Importance of the aim How well the measure achieves it A gentler measure achieves this much as well Harm to the right A toy to show the order of the steps; courts do not use numbers, and the aim is assumed legitimate. Suitable if the measure scores at least 3; fails the necessity step if a gentler measure does at least 80% as well; balanced if benefit (aim × effectiveness ÷ 10) is at least the harm. With the defaults the measure passes the first two steps (the aim is legitimate and the measure helps) and passes necessity (a gentler option does only half as well). It fails at the last step: benefit is 7 × 6 ÷ 10 = 4.2, against a harm of 5. Slide the numbers and watch which step stops it first. The order matters: a measure that fails an early step never reaches the balancing, which is the step most open to argument. The French model: a court inside the state France built a different answer in the aftermath of the Revolution. Revolutionary lawmakers distrusted ordinary judges, so they forbade them from interfering with the administration. The state's own Conseil d'État, created by Napoleon's government in 1799 to advise on laws and settle disputes, grew into a real court. A law of 1872 gave it the power to decide cases itself; its case law shaped modern public law, including state liability (the Blanco decision, 1873) and the tool of the recours pour excès de pouvoir, an open, cheap action to annul any administrative act that breaks the law. Today it is both the government's adviser on draft laws and the top administrative court, with lower administrative courts since 1953 and administrative appeal courts since 1987. Does the arrangement work? Supporters say judges steeped in public administration are expert and firm, and that the action to annul is open to anyone. Critics worry about a court that is also an adviser to the state. Germany has its own branch of administrative courts, separate from its ordinary courts; the English and American systems chose not to separate. The lesson is not that one design is correct, but that every country must decide how to make the state judge itself less. Interactive · Where does a complaint go? United States England and Wales France Germany Brazil Colombia A simplified picture of the usual route for challenging an administrative decision. Real routes depend on the subject (tax, immigration, benefits), have time limits, and are changed by reform. Watchdogs and open files: ombudsmen and transparency laws Courts are slow and expensive, so most systems add cheaper watchdogs. The ombudsman investigates complaints against officials and recommends fixes. Sweden created the first modern one in 1809; Finland followed in 1919, Denmark in 1955, New Zealand in 1962 and the United Kingdom's Parliamentary Commissioner in 1967. Spain's Defensor del Pueblo came with its 1978 constitution, Mexico's national human-rights commission (CNDH) in 1990, and the European Union has its own Ombudsman, established in 1995. Most can recommend but not command, so their power rests on reputation and on officials' wish not to be named. The other tool is the right to see the papers. Sweden's 1766 law on freedom of the press is the oldest, giving public access to official documents. Finland followed in 1951, the US passed its Freedom of Information Act in 1966, and France its law on access to administrative documents in 1978. The world wave came later. Mexico passed a federal law in 2002; India's Right to Information Act and Germany's federal law both date from 2005; Chile's access law took effect in 2009; Brazil's detailed access law is from 2011 and Argentina's national law from 2016. A dozen countries had such laws in 1990 and more than 85 by 2011, according to one count. In 2006 the Inter-American Court of Human Rights recognised access to state-held information as part of freedom of expression, in Claude Reyes v. Chile. Such laws can also be undone. In 2025 Mexico dissolved its autonomous transparency institute (INAI) and moved its functions into a new anticorruption secretariat of the executive branch. The government said transparency would be preserved, and civil-society groups warned that the body deciding whether to release information was now part of the government itself. It is a live argument, not a settled one. Interactive · The spread of access-to-information laws Year Twelve countries picked for this piece, with the year of a first general national access law as given in the sources (Brazil: the 2011 procedures law; the UK: in force 2005; Chile: in force 2009). Not a world count, and "first law" is not the same as an effective one. What a graduate just sees Officials may do only what a law lets them do, and a court can check. A court usually asks whether a decision was lawful, not whether it was best. Illegality, irrationality, unfair procedure and disproportion are four different ways to lose. Deference is a dial between expert agencies and independent judges, and the settings change with the politics. Proportionality is an ordered checklist, and an early failure ends the case. Some countries have a second set of courts for the state; others have one. A watchdog or a public file is a cheap check, but only as good as its independence. Where it shows up next Constitutional Law (35/03): the same courts that guard rights review the officials. European Union Law (35/11): proportionality is a general principle of EU law (Article 5 of the Treaty on European Union), applied to national and EU measures. Public Policy (35/16): every policy is delivered through permits, rules and benefits that can be reviewed. In the world: a benefits tribunal, an environmental permit fight, a freedom-of-information request by a newsroom, a regulator that loses in court. If you want to go deeper Standard textbooks: Stephen Breyer, Richard Stewart, Cass Sunstein, Adrian Vermeule and others, Administrative Law and Regulatory Policy (US casebook); Peter Cane, Administrative Law, or Carol Harlow and Richard Rawlings, Law and Administration (UK and comparative). Check for current editions. Comparative: Aharon Barak, Proportionality: Constitutional Rights and Their Limitations (2012). Gentler: James Q. Wilson, Bureaucracy: What Government Agencies Do and Why They Do It (1989). Free course: the Open University's OpenLearn law units, for example Judicial decision making, which covers how courts reason about decisions. The takeaway Government acts through officials, so the law of government is the law of officials: the power must come from a law, the process must be fair, the reasons must make sense, and a person must be able to challenge it. Countries differ on which courts review, how much they defer, and whether they ask the proportionality questions. Watchdogs and open-records laws add cheaper checks, and all of these can be strengthened or weakened by politics. Try this: next time an agency does something in the news, name the power it claims, the process it followed, who could challenge it and where, and whether the public can see the papers. Sources & Further Reading Sources. Loper Bright Enterprises v. Raimondo (28 June 2024; 6-2; overruled Chevron (1984)); Basic Law Art. 19(4) (English translation, Federal Ministry of Justice); Brazil Constitution Art. 5 XXXV; Conseil d'État history (1799; 1872; tribunaux administratifs 1953; cours administratives d'appel 1987), per Wikipedia and public sources; Blanco (1873), Wednesbury (1948), GCHQ (1985), Mathews v. Eldridge (1976), State Farm (1983), Marbury (1803), the Pharmacy decision (1958) and R v. Oakes (1986) are standard case-law landmarks taught in every public-law syllabus. Origins of proportionality in Prussian administrative courts: summary on Wikipedia, "Proportionality (law)". Ombudsman dates: Wikipedia, "Ombudsman". Freedom-of-information dates: Wikipedia, "Freedom of information laws by country" (Sweden 1766, Finland 1951, France 1978, Colombia 1985, Brazil 1991 and 2011, Chile 2009, Argentina 2016, India and Germany 2005); US FOIA 1966, UK FOIA 2000, Mexico 2002 are standard references. Mexico's INAI: Mexican press reports of March 2025 (Expansión, Por Esto, Excélsior). The 2006 Inter-American Court judgment: Claude Reyes v. Chile. 🌐 OpenLearn: Judicial decision making 📘 Breyer et al., Administrative Law and Regulatory Policy 📘 Harlow & Rawlings, Law and Administration 📘 Barak, Proportionality Step 11. International Law & Human Rights: Rules Between Nations Without a World Police --------------------------------------------------------------------------------------- Why: Treaties, human rights courts and law between nations. Nobody can arrest a state. Yet ships dock, planes land, borders mostly hold and a handful of dictators have ended up in the dock. How law works when the only lawmakers are the ones it binds. select{font-family:-apple-system,sans-serif;font-size:.9rem;min-height:44px;max-width:100%;min-width:0;border:1px solid var(--line);border-radius:10px;background:var(--hi);color:var(--ink);padding:6px 8px} .row{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:6px 0} .row>*{min-width:0} .opt{display:block;width:100%;text-align:left;border-radius:12px;margin:6px 0} Park an embassy car in front of a fire hydrant in almost any capital in the world and the ticket will quietly go nowhere. The diplomat inside cannot be arrested or sued in the country where they serve, under a treaty (the 1961 Vienna Convention on Diplomatic Relations) that nearly every state has joined. No police force makes anyone keep it. States keep it because each of them wants its own diplomats treated the same way abroad. That is the whole puzzle of this subject in one parking space. Inside a country, law has a legislature that writes it, courts that apply it and police who enforce it. Between countries there is no world parliament, no court every state must obey, and no world police. The international lawyer Louis Henkin put the surprising result well in 1979: almost all nations observe almost all principles of international law and almost all of their obligations almost all of the time. The headlines are about the exceptions. This piece is about why the rule is so often the rule. The course in one box Who takes itLaw students in their later years (an elective in many US law schools; a standard course, Derecho Internacional Público, in the five-year degrees of Spain and Latin America), and political science and international relations majors. What it is forTelling a rule that states are bound by from a mere aspiration, and knowing which body, if any, can say so. Comes afterConstitutional Law (35/03): you need to know what a domestic legal order is before asking what changes when there are many. Leads toEuropean Union Law (35/11), the deepest case of states sharing sovereignty, and International Relations (35/14). What this piece gives youYou will not be able to argue a case at the Hague. You will see where the rules come from, why a veto matters, which court hears what, and why compliance is common even without police. It describes how legal systems work and is not legal advice; treaties change and countries differ. Easier first reads: The International Institutions: What They Can and Can't Do (18/10) and Rights, Constitutions & the Rule of Law (18/04). Where the rules come from: treaties, custom and principles Every legal system has to answer one question first: what counts as law? Statute and precedent answer it at home. Between states, the answer is written in Article 38 of the Statute of the International Court of Justice (1945), which lists what the Court applies: treaties, custom, and general principles of law recognised by civilised nations (an old phrase, now read as principles found in the world's legal systems, such as good faith). Court decisions and scholars' writings are only "subsidiary means" of finding the law. A treaty binds the states that join it, because of a rule so basic it is the first rule of the subject: pacta sunt servanda, agreements must be kept (Article 26 of the 1969 Vienna Convention on the Law of Treaties). A treaty usually says when it comes into force, often after a number of ratifications. Custom is harder to see. It is a practice states follow because they believe the law requires it. Two ingredients: what states actually do (state practice) and why they do it (opinio juris, the sense of legal obligation). The International Court asked for practice that is "extensive and virtually uniform", including among the states most affected, in the North Sea Continental Shelf cases (1969). Custom matters because it binds even states that never signed anything. A state that objects from the start and keeps objecting (a persistent objector) can escape a new custom, but not the few peremptory norms (jus cogens), such as the bans on genocide and slavery, which no treaty can override (Article 53 of the Vienna Convention). Interactive · Is it custom yet? Share of states that act this way Most-affected states do it Most-affected states don't "Because the law requires it" Courtesy or convenience A teaching toy: score = practice × (1 if the most-affected states join, else 0.6) × (1 if from a sense of legal duty, else 0.25). Real tribunals weigh evidence, not scores. At 70 or above: likely custom; 40 to 70: emerging or doubtful; below 40: not custom. Why does "courtesy or convenience" matter? Because ships of every flag stay out of each other's way at sea, but that alone is a habit; custom needs the belief that doing otherwise would be a breach. Now the treaty side: a treaty is not law for anyone until enough states say yes. Interactive · When does a treaty start to bind? Treaty Vienna Convention on the Law of Treaties (1969) Rome Statute of the ICC (1998) Law of the Sea Convention (1982) Paris Agreement (2015) Ratifications so far Share of world emissions those parties cover (Paris only) Thresholds: Vienna Convention 35 ratifications (Art. 84); Rome Statute 60 (Art. 126); Law of the Sea 60, then a 12-month wait (Art. 308); Paris Agreement 55 parties covering at least 55% of emissions (Art. 21). Real entry into force also counts days after the last deposit. Each of the three families of states treats the result differently at home. This is the first big comparison in the subject: when a treaty binds the country, does it also bind its courts and citizens automatically? FamilyHow treaties enter domestic law United States (common law)A treaty the Senate approves by two-thirds is "supreme law of the land" (Constitution, Art. VI), but courts treat many as non-self-executing: they need a statute before a private person can invoke them. The US has not joined the Rome Statute and has signed but not ratified the American Convention on Human Rights. Latin America (civil law)Often generous. Argentina's 1994 constitution gives listed human rights treaties constitutional rank (Art. 75 no. 22); Colombia's courts speak of a bloque de constitucionalidad (Art. 93); Brazil's 2004 amendment gives human rights treaties approved by supermajority the rank of constitutional amendments; Mexico's 2011 reform puts treaty rights alongside the constitution's own (Art. 1). Continental EuropeFrance's 1958 constitution puts ratified treaties above statutes (Art. 55); Germany ranks general rules of international law above statutes (Art. 25) while treaties generally have statute rank. The UK is dualist: a treaty needs a statute, which is why it passed the Human Rights Act 1998. The Charter's bargain: force is banned, the Council decides The biggest treaty of all is the UN Charter, signed at San Francisco on 26 June 1945 and in force from 24 October 1945. Its central rule is Article 2(4): states must refrain from the threat or use of force against another state's territorial integrity or political independence. It had two exceptions: self-defence against an armed attack (Article 51), and action authorised by the Security Council under Chapter VII. That second exception is the Charter's bargain, and it shows why the subject is half law and half politics. The Council has 15 members, five of them permanent: China, France, Russia (which took the Soviet seat), the United Kingdom and the United States. A resolution needs nine "yes" votes, and under Article 27(3) a negative vote by any permanent member blocks it: the veto. A permanent member that merely abstains does not block it, by long practice. The design is deliberate: in 1945 the founders thought a rule that the great powers could outvote would be a rule they would leave. Interactive · Can this resolution pass? United States United Kingdom France Russia China Elected members voting yes (of 10) Rule (Charter Art. 27): at least 9 yes votes of 15, and no permanent member voting no. Abstentions count as neither. Notice what the veto does not do: it does not make the underlying rule disappear. A blocked resolution leaves Article 2(4) in place; it only removes the Council as the body that can authorise enforcement. When the Council is stuck, the General Assembly can debate and condemn (its resolutions are recommendations, not law), and the International Court can give opinions. In March 2022 the Court, by 13 votes to 2, ordered Russia to suspend its military operations in Ukraine while the case was heard. The order was binding in law and was not followed in fact. Both halves of that sentence are part of the subject. Courts for states and for people: the ICJ and the ICC Two courts in the Netherlands are constantly confused. The International Court of Justice (ICJ, the "World Court", at the Peace Palace in The Hague) is the UN's main judicial organ. Fifteen judges, elected for nine-year terms, settle disputes between states, and give advisory opinions when UN bodies ask. The catch is consent: a state can be sued only if it has accepted the Court's jurisdiction, by treaty clause, by a special agreement, or by a standing declaration. Nicaragua v. United States (1986), where the Court found the US had breached customary law by supporting the Contras and mining Nicaraguan harbours, shows both sides: a state can be judged, and the judged state can ignore it. Judgments are meant to be enforced through the Security Council (Charter Art. 94), where the veto sits. The International Criminal Court (ICC) is a different animal: a treaty court created by the Rome Statute (adopted 17 July 1998, in force 1 July 2002) that tries individuals for genocide, crimes against humanity, war crimes and aggression. It is a court of last resort: under complementarity, it acts only when national courts are unable or unwilling to genuinely investigate. The ICC says 125 states were parties in mid-2026; several states have filed notices of withdrawal that take effect in 2027. The US, China, Russia and India are not parties. Supporters say it ended the idea that rank protects; critics say its docket has been uneven and its cases dependent on state cooperation for arrests. Both statements describe real features: the Court has no police of its own. Interactive · Which forum? Predict, then reveal Next case Human rights courts: Europe, the Americas and Africa Human rights law turns the traditional picture around. Treaties between states used to be about what states owed each other. After the horrors of the Second World War, the Universal Declaration of Human Rights (General Assembly, 10 December 1948; adopted 48 to 0 with 8 abstentions) said every person has rights against their own government. The Declaration is not a treaty. Two treaties made it binding in 1966 (in force 1976): the Covenants on Civil and Political Rights and on Economic, Social and Cultural Rights. The global system mostly works through committees that review reports. The sharper teeth are regional. SystemFounding textWho can bring a caseCourt Europe (Council of Europe)European Convention on Human Rights, signed 1950, in force 1953Any individual, directly, after exhausting national remedies (since 1998)European Court of Human Rights, Strasbourg The Americas (OAS)American Declaration (1948); American Convention (1969, in force 1978)Individuals go to the Commission (Washington) first; the Commission or a state brings the case to the CourtInter-American Court, San José, Costa Rica Africa (AU)African Charter on Human and Peoples' Rights (1981, in force 1986)The Commission (Banjul); direct individual access to the Court only if the state made a special declarationAfrican Court, Arusha, Tanzania The European system is the most used: its judgments are routinely followed, partly because they are supervised by the Council of Europe's ministers, and partly because Europeans' own courts cite them. Russia was expelled from the Council of Europe in March 2022 and ceased to be a party to the Convention in September 2022. The Inter-American Court's landmark is Velásquez Rodríguez v. Honduras (1988): a student who disappeared at the hands of state agents. The Court held that a state must prevent, investigate and punish such violations, even when it did not itself commit a particular one. Later it developed "conventionality control": national judges should check domestic law against the Convention. The African Charter is distinctive in listing the rights of peoples and the duties of individuals alongside individual rights. Its Court's reach is thinner: of the few states that accepted direct individual petitions, several (including Rwanda, Tanzania, Benin and Côte d'Ivoire) have since withdrawn the declaration. The same pattern appears elsewhere: courts are strongest where governments choose to leave their doors open. Rights are also not the same everywhere. The Charters differ on which rights, how they are limited, and whose duties come with them. A fair summary is that they share a core (life, freedom from torture, fair trial) and differ at the edges. Enforcement without a world police If nobody enforces, why comply? Lawyers and political scientists give overlapping answers, and they do not all agree on the weights. Reciprocity: a state that breaks a treaty invites others to break it back. Reputation: a state known to cheat finds fewer partners next time, and nearly every state is in a long series of repeated dealings. Countermeasures and sanctions: injured states can respond in proportion; the Security Council can impose sanctions. Domestic courts and politics: in many countries judges apply international law, and a government answers to voters, press and its own officials. Habit and shared interest: air traffic, mail and borders work because everybody gains from the rule. Realists such as Hans Morgenthau and, more sceptically, Jack Goldsmith and Eric Posner argue that states follow law when it matches their interest and that the rule's apparent force is mostly coincidence. Institutionalists and Henkin's tradition argue the rule itself changes states' calculation and what they can justify. The data cannot settle this, because the easy cases are chosen by the states themselves. What both sides agree on: the cases of defiance are costly and rare, and powerful states can resist more cheaply. Interactive · Should this state break the rule? Gain from breaking it Chance the breach is noticed and attributed Cost of retaliation if noticed Value of a good reputation for keeping promises No veto (retaliation fully applies) Holds a veto (Council sanctions off the table) Expected net gain = gain − chance × (retaliation + reputation lost). In this toy half of retaliation runs through the Security Council, so a veto-holder escapes that half. Invented numbers, in arbitrary units: it shows how the factors interact, not what any real state would do. Drag the chance of being noticed to 100% and the reputation value up: even a big gain stops paying. Drag it to 10% and the same rule becomes a suggestion. That is why transparency (inspections, reporting, a free press) does so much work in international law: it raises the chance of being noticed. Who judges the judges: universal jurisdiction, immunity and the critics One more route fills part of the gap. Some crimes (torture, genocide, war crimes) are so serious that any state's courts may try them wherever they happened: universal jurisdiction. In October 1998 British police arrested the former Chilean ruler Augusto Pinochet in London on a Spanish judge's warrant; the House of Lords held that a former head of state could not claim immunity for torture, and he was eventually sent home on health grounds rather than tried abroad. A US court in Filártiga v. Peña-Irala (1980) heard a Paraguayan family's claim over a torture death. The offence was committed abroad by a foreigner. It cuts both ways. Immunity protects serving heads of state and diplomats from foreign courts, to let governments function (the ICJ confirmed it in the Arrest Warrant case, 2002). Critics from Africa and the Global South have charged that universal jurisdiction and the ICC are used against weaker states while great powers escape; defenders answer that the answer to selective justice is more justice, and that national courts, including Argentina's under universal jurisdiction, have opened cases the home courts would not. The honest summary: international law is a real, imperfect, evolving legal order, strongest where states have chosen to bind themselves and weakest where power and law collide. What a graduate just sees Ask first: which source, treaty or custom? A treaty binds only parties; custom can bind everyone; jus cogens binds even over a treaty. Consent is the master key: jurisdiction, treaties and judgments all begin with a state saying yes. Reading a news item about a court, ask "which court, who can sue, who is the defendant?" before anything else. The ICJ tries states, the ICC tries people. A veto is not a ruling that the rule is gone, only that the Council will not enforce it. Compliance is the norm and defiance the news; most of the work is done by reciprocity, reputation and being watched. The regional human rights systems have different founders, different doors, and different records. "International" is not one thing. Whenever a state is accused, the first reply is usually jurisdiction or immunity, not the facts. Learn the objection as well as the claim. Where it shows up next European Union Law (35/11): the same ideas pushed further. The EU's court made its treaties directly effective for individuals, which is exactly what an ordinary treaty does not do. International Relations (35/14): realists, liberals and constructivists disagree about precisely the compliance question above. Constitutional Law (35/03): how a constitution lets treaties in (see the table above) is part of every national legal system. In the world: trade disputes at the WTO, maritime boundaries and fishing rights, refugee protection, sanctions, war crimes investigations, climate treaties, and the ICC's Ukraine and Palestine investigations. If you want to go deeper 📘 Textbook. Malcolm Shaw, International Law (Cambridge University Press, 9th edition, 2021). A widely assigned, comprehensive survey. 📘 Textbook. James Crawford, Brownlie's Principles of Public International Law (Oxford, 9th edition, 2019). The other standard choice, strong on sources and state responsibility. 📘 Gentler. Philippe Sands, East West Street (2016): how two lawyers, Lauterpacht and Lemkin, invented "crimes against humanity" and "genocide", told as a family detective story. 🌐 Free course. The United Nations Audiovisual Library of International Law: free lectures by leading international lawyers, plus the texts of the treaties themselves. The takeaway International law is law made by the states it binds: treaties by consent, custom by practice believed to be obligatory. The UN Charter bans force and gives enforcement to a Council with five vetoes; the ICJ judges states if they consent; the ICC tries individuals when national courts will not; regional courts give people direct rights where governments allow. With no police, it works through reciprocity, reputation and being watched, which is why it usually holds and sometimes fails where it matters most. Try this: next time international law is in the news, write down three things before reading the story: which source (treaty or custom), which court or body, and whether that body's jurisdiction depends on the accused state's consent. Sources & Further Reading Sources. Statute of the ICJ, Art. 38; Vienna Convention on the Law of Treaties 1969 (Arts. 26, 53, 84); UN Charter (Arts. 2(4), 27, 51, 94); ICJ, North Sea Continental Shelf (1969), Nicaragua v. United States (1986), Arrest Warrant (2002), and the order of 16 March 2022 in Ukraine v. Russian Federation (13 to 2); Rome Statute (adopted 17 July 1998, in force 1 July 2002; 125 states parties per the ICC Assembly of States Parties Presidency, June 2026, with withdrawals by Burkina Faso, Mali and Niger taking effect in 2027); ECHR, American Convention and African Charter texts; Council of Europe resolution and Russia's cessation of membership (March and September 2022); Velásquez Rodríguez v. Honduras (Inter-American Court, 1988); African Court Art. 34(6) declarations and the withdrawals of Rwanda, Tanzania, Benin and Côte d'Ivoire (African Court and Pretoria Centre for Human Rights statements); Henkin, How Nations Behave (1979); Goldsmith & Posner, The Limits of International Law (2005). Constitutional article numbers are from the national texts and should be checked against current versions. The interactives' numbers are toy models computed in node; thresholds from the treaty articles. 🌐 UN Audiovisual Library of International Law 📘 Shaw, International Law; Crawford, Brownlie's Principles of Public International Law 📘 Sands, East West Street Step 12. European Union Law: The Deepest Legal Union, and Its Rivals -------------------------------------------------------------------- Why: The world's deepest legal union, and its rivals in Latin America and Africa. Twenty-seven countries let one court tell their own judges which law wins. How that happened, how it works, and which regions in Latin America and Africa tried the same thing and what they kept. select{font-family:-apple-system,sans-serif;font-size:.9rem;min-height:44px;max-width:100%;min-width:0;border:1px solid var(--line);border-radius:10px;background:var(--hi);color:var(--ink);padding:6px 8px} .row{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin:6px 0} .row>*{min-width:0} .grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(104px,1fr));gap:6px;margin:8px 0} .grid button{border-radius:10px;padding:6px 6px;font-size:.78rem;min-width:0} .steps{font-family:-apple-system,sans-serif;font-size:.92rem;padding-left:1.3em} .steps li{margin:.3em 0;color:var(--muted)} .steps li.on{color:var(--ink);font-weight:700} A phone charger bought in Lisbon works in Warsaw. A Greek engineer can take a job in Finland without a work permit. A bank in Dublin can lend to a company in Madrid under one set of rules. None of this is an accident of friendly neighbours. It is the visible surface of a legal system in which a court in Luxembourg, whose judges come from every member state, can tell a judge in Rome or Riga that a national law must be set aside. Nothing like it exists between ordinary states. In International Law & Human Rights (35/10) you saw that a treaty normally binds governments, not individuals, and that no court can override a national parliament. EU law broke both rules. That makes it the most studied experiment in sharing sovereignty, and a natural comparison for every region that has tried regional integration since. The course in one box Who takes itLaw students across Europe, usually in years 3 to 5, where it is compulsory in most countries' law degrees; an elective in the US, Canada and Latin America; also political science majors. What it is forKnowing which rules come from Brussels and Luxembourg rather than your own capital, and how a person can use them. Comes afterConstitutional Law (35/03) and International Law & Human Rights (35/10). Leads toCompetition, trade, data-protection and migration law; Comparative Politics (35/13) and Political Economy (35/17). What this piece gives youYou will not be able to brief a case at the Court of Justice. You will see why direct effect and supremacy made this order unusual, how the single market and the voting rules work, and what the imitators kept and left out. It describes how legal systems work and is not legal advice; EU law changes and each country applies it differently. Easier first read: The International Institutions: What They Can and Can't Do (18/10). A new legal order: direct effect and supremacy The European Economic Community began with the Treaty of Rome (signed 1957, in force 1958) among six states: Belgium, France, Italy, Luxembourg, the Netherlands and West Germany. On paper it was an ordinary treaty. Two judgments from its Court of Justice, within eighteen months of each other, turned it into something else. In Van Gend en Loos (Case 26/62, 5 February 1963) a Dutch transport firm objected to a customs duty on a chemical imported from Germany, relying on a Treaty article that banned new duties between member states. Could a private company invoke a treaty article against its own government before its own judge? The Court said yes: the Community was "a new legal order of international law" whose subjects were not only states but their citizens. This is direct effect. The test the Court gave: the provision must be clear and precise, unconditional, and not need further national measures to work. In Costa v ENEL (Case 6/64, 15 July 1964), an Italian lawyer protesting the nationalisation of electricity claimed the Italian law clashed with the Treaty. The Court held that law stemming from the Treaty, "an independent source of law", could not be overridden by domestic provisions without losing its character as Community law. This is supremacy (or primacy): where the two collide, EU law wins. Later cases added that a national judge must set aside the clashing national law at once, without waiting for parliament (Simmenthal, 1978), and that a state that fails to implement EU law can owe damages to those harmed (Francovich, 1991). The EU's legal acts come in kinds (Treaty on the Functioning of the EU, Art. 288). A regulation applies directly in every state. A directive binds states as to a goal but leaves the method to them, so it needs national law to implement it. A directive can be invoked against the state once the deadline has passed, but not directly against a private company. Interactive · Can I rely on this rule in a national court? The EU rule is A Treaty article A regulation A directive against The state or a public body A private company or person Clear, precise and unconditional Vague or needs further measures Directive deadline has passed Deadline not yet passed Simplified from Van Gend en Loos (1963), Van Duyn (1974), Defrenne II (1976, equal pay between private parties), Marshall (1986), Marleasing (1990) and Francovich (1991). Real cases turn on the exact wording. The four freedoms and the single market The purpose of all this was a common market with four freedoms: goods, persons (workers and, later, citizens), services and capital moving across borders as they do inside a country. Customs duties between members were removed by 1968. The harder barriers were rules. If every state forbids what another allows, goods still stop at the border. The key case is Cassis de Dijon (Case 120/78, 20 February 1979). Germany required fruit liqueurs to contain at least 25% alcohol. A French blackcurrant liqueur, legal in France, was around 15 to 20%, so a German importer was refused. The Court held that a product lawfully sold in one member state should in principle be sold in all: mutual recognition. A state may still block it, but only for a real public-interest reason (health, consumer protection, the environment, fair trade) and only if the rule is proportionate: no more restrictive than needed. Germany's argument, that consumers should be protected from weak drinks, failed, because a label would do the job. The Court's later Keck judgment (1993) carved out ordinary "selling arrangements" (shop hours, say) applied equally to all, which are not caught. Interactive · Is this national rule allowed? Case A simplified test: (1) a pure selling arrangement treated equally is outside the rules (Keck); (2) otherwise a rule that hinders imports needs a genuine public-interest aim and no less restrictive alternative. Real courts weigh the evidence, case by case. Toggle each fact to see what changes. The institutions: who proposes, who decides The EU's institutions do not map neatly onto a national government. Think of five jobs. The European Commission (one commissioner per state, 27) holds the monopoly of proposing most laws and acts as "guardian of the Treaties", bringing infringement cases against states (Art. 258 TFEU). The European Parliament (720 members, directly elected since 1979; the current size dates from the June 2024 election) and the Council of the EU (ministers of the 27 governments) co-decide most laws in the "ordinary legislative procedure". The European Council (heads of state or government) sets direction but does not legislate. And the Court of Justice of the European Union in Luxembourg, with a judge per member state, interprets the Treaties. These arrangements come from the Lisbon Treaty (signed 2007, in force 1 December 2009), which also made the Charter of Fundamental Rights binding. The Council usually votes by qualified majority: at least 55% of member states (at least 15) representing at least 65% of the EU's population (Art. 16 TEU). To block, you need at least four states. Population matters, but the small states count too. Try building a majority. Interactive · Build a qualified majority Germany, France, Italy, Spain The six founders Everyone but the big four All 27 Clear Populations: Eurostat, 1 January 2025 (total 450.4 million), rounded in the page. Rule: 15 states, 55% of states and 65% of population in favour. A blocking minority needs at least four states and more than 35% of the population. Most laws also need a majority in Parliament. The Court and the preliminary reference How does a court in Luxembourg shape law in 27 countries without an army of its own? Through the national judges. Under Article 267 TFEU, any national court may pause a case and ask the Court of Justice what a rule of EU law means (or whether an EU act is valid). A court of last resort must ask when the question is real and not already settled (the CILFIT exceptions, 1982). The Court answers the question, not the case. The national court applies the answer. This keeps the system decentralised: each ordinary judge in Europe is also an EU judge, and the Court gets cases from people who sued for the most ordinary reasons. Van Gend itself arrived this way, from the Dutch tax tribunal, and so did hundreds of landmark rulings on worker rights, product safety and data protection. The cost is time: a reference often adds well over a year. Interactive · A reference, step by step BackNext step When national courts push back Supremacy is the Court of Justice's view. National constitutional courts have their own, and the friction is part of the law. Germany's Federal Constitutional Court said in Solange I (1974) that it would check EU measures against German basic rights "so long as" the EU lacked its own protection; in Solange II (1986) it stepped back, as the EU's protection had matured. In May 2020 the same court, in the PSPP decision on European Central Bank bond purchases, held that a Court of Justice ruling had gone beyond its powers, something the EU Court insists only it can decide. In October 2021 Poland's Constitutional Tribunal (judgment K 3/21) held parts of the EU Treaties incompatible with the Polish constitution, which the Commission and many Polish and European lawyers contested because that tribunal's independence was itself in question. Both episodes show the same thing: supremacy depends on national courts accepting it, and on their willingness to let the EU Court have the last word. And the exit door is real. Article 50 of the Treaty on European Union lets a state leave. The United Kingdom did, on 31 January 2020. Rivals and imitators: Latin America and Africa Regional blocs elsewhere borrowed the European template, but each stopped at a different point, and for reasons law students should understand rather than dismiss. Presidents in Latin America and Africa were wary of handing sovereignty to a court, and many blocs were built to trade and to protect young states, not to dissolve borders. BlocFoundingCourtHow far it goes Mercosur (Argentina, Brazil, Paraguay, Uruguay, Bolivia since 2024; Venezuela suspended since 2016)Treaty of Asunción, 26 March 1991Permanent Review Tribunal, Asunción (Protocol of Olivos, 2002)Intergovernmental: rules must be incorporated by each state's own procedure. Tribunal rulings bind the parties but there is no direct effect for individuals and no supremacy doctrine; advisory opinions to national courts are not binding. Andean Community (Bolivia, Colombia, Ecuador, Peru)Cartagena Agreement, 26 May 1969; Chile left 1976, Venezuela 2006Andean Court of Justice, Quito (treaty 1979; working since the 1980s)The closest to the EU: community decisions apply directly and prevail over national law; national courts of last resort must ask the Court for an interpretation, modelled on Article 267. ECOWAS (West Africa; Mali, Burkina Faso and Niger left in January 2025)Treaty of Lagos, 1975; revised 1993Community Court of Justice, AbujaSince 2005 individuals can bring human rights cases against member states directly, an EU-like step; compliance depends on national governments. Free movement of persons since 1979. African UnionConstitutive Act, Lomé 2000; launched Durban 2002 (replacing the OAU of 1963)The planned Court of Justice never became operational; the African Court sits at ArushaUnusual rights-of-intervention clause (Art. 4(h)) and suspension of governments that take power unconstitutionally; free trade area (AfCFTA) trading since 2021. The pattern is instructive. The Andean model copied Luxembourg closely and has been used, yet the Community has shrunk. Mercosur grew politically (new members, a Parliament) with a thin legal core. West Africa's court won individual access while its member states' commitment wavered. And the Southern African Development Community's own tribunal was suspended in 2010 after it ruled against Zimbabwe's land seizures in Campbell v Zimbabwe (2008), and later lost individual access: the clearest case of what happens when a regional court rules against a government that can switch it off. What made the EU different? Defenders credit post-war trust, deep economic interdependence, and national judges willing to act as EU judges. Sceptics add that the EU's courts also benefited from member states that let the Court expand its powers without a vote, which is itself contested inside Europe. What a graduate just sees The EU is a legal order, not only a market: its rules reach individuals and prevail over national law. Direct effect asks one question: is the rule clear, unconditional and ready to apply without more national law? A regulation is a law; a directive is an order to make a law, and it is the state, not a firm, that is held to it. "Mutual recognition" means: if it is legal in one member state, begin by assuming it can be sold in all. Qualified majority voting needs both heads and heads of population. Small states can block; big ones cannot rule alone. A preliminary reference lets any national judge ask Luxembourg; the Court answers the question, the national court decides the case. Supremacy is a conversation: constitutional courts accept it with conditions. Regional courts elsewhere reflect how far each bloc's governments were willing to be bound. Where it shows up next Comparative Politics (35/13): compare the EU to a federation (the US) and to a looser confederation; each answers who holds sovereignty. Political Economy (35/17): the euro and the single market's effect on trade and inequality. In the world: the GDPR (2018), roaming charges, passenger rights on flights, product labels, the "Brussels effect" on companies that follow EU rules globally, and the post-Brexit arguments over trade rules with the UK. In your own career: a lawyer in Madrid, a diplomat in Brasília dealing with Mercosur-EU trade talks, or a compliance officer in Lagos exporting to Europe will all deal with this law. If you want to go deeper 📘 Textbook. Paul Craig and Gráinne de Búrca, EU Law: Text, Cases, and Materials (Oxford University Press, 8th edition, 2024). The standard comprehensive text, strong on cases. 📘 Textbook. Damian Chalmers, Gareth Davies and Giorgio Monti, European Union Law (Cambridge University Press). A more critical and political-economy-minded alternative; check the current edition. 📘 Gentler. John Pinder and Simon Usherwood, The European Union: A Very Short Introduction (Oxford). Short, few legal terms. 🌐 Free resources. EUR-Lex, the EU's free database of treaties and judgments (including Van Gend, Costa and Cassis in all official languages), and the Court of Justice's own site. The takeaway EU law is what you get when a treaty is allowed to reach individuals (direct effect) and to win over national law (supremacy), enforced through ordinary national judges who can ask Luxembourg (the preliminary reference). Four freedoms and a qualified-majority vote make the single market. Elsewhere, the Andean Community copied the court, Mercosur and the African Union kept their sovereignty, and West Africa went partway. The measure of any regional law is how far its governments are willing to be bound. Try this: look at the bottom of a product you own, a charger, toy or food label. Find the CE mark or an EU-style label. It is the single market's rules, printed on an object. Sources & Further Reading Sources. CJEU: Van Gend en Loos (26/62, 1963), Costa v ENEL (6/64, 1964), Van Duyn (41/74), Defrenne II (43/75), Simmenthal (106/77), Cassis de Dijon (120/78), Marshall (152/84), Marleasing (C-106/89), Francovich (C-6/90), Keck (C-267/91), CILFIT (283/81); TFEU Arts. 258, 267, 288; TEU Arts. 16, 50; Lisbon Treaty (signed 13 December 2007, in force 1 December 2009). Bundesverfassungsgericht, Solange I (1974), Solange II (1986), PSPP (5 May 2020); Polish Constitutional Tribunal K 3/21 (7 October 2021). Populations: Eurostat, 1 January 2025 (via the Wikipedia list of EU states by population; total 450,380,300). Mercosur (Treaty of Asunción 1991; Olivos 2002; Bolivia a full member since July 2024; Venezuela suspended since December 2016), Andean Community (Cartagena Agreement 1969; Andean Court seated in Quito), ECOWAS (Treaty of Lagos 1975; Sahel states' exit January 2025), AU Constitutive Act (2000). Textbook editions: Craig & de Búrca, 8th ed., OUP 2024 (bookseller listings; check the publisher). The qualified-majority calculation was computed in node; the national-rule and direct-effect tools are simplified teaching models. 🌐 EUR-Lex 🌐 Court of Justice of the European Union 📘 Craig & de Búrca, EU Law: Text, Cases, and Materials Step 13. Business Law & Ethics: Who Is Allowed to Do What, and Who Pays When It Goes Wrong ------------------------------------------------------------------------------------------ Why: Companies, contracts and ethics in business. Every company is a bundle of promises, a legal person that can be sued, and a set of people with duties. The rules differ by country in ways that decide who loses when a business fails. You tap "I agree" on terms nobody reads, buy a coffee, start a job, open a shop. Each act is quietly legal. The coffee is a sale contract. The job is an employment contract with rules the law adds whether you wrote them or not. The shop may be a "company", which the law treats as a separate person that owns the lease and owes the suppliers, so that you, the owner, can walk away from its debts. Most of that is invisible until something breaks: a supplier does not pay, a customer is hurt, a founder is fired, a boss lies to investors. Then the questions are old and practical. Was there a deal? Who is responsible? How much? A business graduate does not become a lawyer. They learn which questions to ask before a lawyer is needed, and that the answers change at a border. This piece describes how legal systems work in general. It is not legal advice, and statutes, courts and thresholds change. For a real decision, ask a lawyer qualified where you are. The course in one box Who takes itBusiness students, usually in years 1 to 3, as "legal studies" or "business law" (it is part of the Wharton core), and managers in MBA courses on ethics and corporate accountability. Programmes differ in how much is law and how much is ethics. What it is forKnowing what a promise, a company, a product and a job oblige you to, and what a manager owes to owners, staff and the public. Comes afterNothing in the map; it is a standalone entry point. Leads toNothing is formally built on it, but it sits behind Strategy & Competition (34/54, where antitrust lives), Entrepreneurship (34/56) and Organizational Behavior & Leadership (34/53). The Law major on the roadmap will reuse it. What this piece gives youYou will not be able to draft a contract or argue a case. You will see why a handshake deal may or may not bind in two countries, why owners of a company usually cannot be chased for its debts, and why famous scandals are rarely the story the internet tells. An easier first read: The Legal Bare Minimum (04/04). Two families of law, and a layer on top A judge faces a dispute that no rule clearly covers. What does she do? In the common-law family she looks at how earlier judges decided similar disputes and follows them (the principle of precedent, stare decisis). The law grew case by case in England and travelled with the British Empire: the United States, Canada (except Quebec's private law), Australia, India, Nigeria and many more. Statutes matter a great deal, but they are read against the decisions. In the civil-law family she starts from a code, a systematic text drafted by scholars and legislators: France's Code civil (1804, the "Napoleonic Code"), Germany's BGB (in force 1900). She finds the article, interprets it, and decides. Earlier decisions are not formally binding, though in practice courts watch each other closely. Latin America is overwhelmingly civil-law: Chile's Civil Code was drafted by Andrés Bello in the 1850s, Brazil's current code dates from 2002, and Mexico has federal codes plus state codes. Some places mix both: Scotland, Louisiana, Quebec, South Africa. The honest picture is convergence. Common-law countries pass vast statutes; civil-law courts publish decisions and mostly follow them. The difference is in the starting point and the habit of reasoning, which still shapes how contracts are written (long and defensive in the common-law world, shorter where the code supplies the gaps). On top sits EU law, a third layer for 27 member states. Regulations apply directly everywhere (the data-protection regulation GDPR). Directives set a goal and each country writes its own law to meet it. The European Court of Justice established in Van Gend en Loos (1963) and Costa v ENEL (1964) that EU law can be invoked by individuals and wins over conflicting national law. Interactive · Which family, which main source? Simplified summaries of how each system is usually classified; real systems blend sources. A contract is a promise the law will enforce Not every promise binds. "I'll lend you my bike" does not; "I'll sell you my bike for 100" does. English-style common law asks for offer (a definite proposal), acceptance (agreement to exactly those terms; a changed term is a counter-offer, not an acceptance), consideration (each side gives something of value, though it need not be fair: a peppercorn can do) and an intention to be legally bound. A promise by deed, a formal signed document, needs no consideration. A promise for something already done ("thanks for last week, I'll pay you 50") is past consideration and generally fails, with narrow exceptions such as Pao On v Lau Yiu Long. Civil-law codes ask instead for consent, capacity and a lawful content. Some also demand a cause, the reason the party binds themselves. Chile's Civil Code (art. 1445) lists capacity, consent, a lawful object and a lawful cause; Spain's code asks for consent, object and cause, and says that in a contract that rewards a service, the cause is that service (art. 1274). So Spain would enforce the "thanks for last week" promise where England would not. France removed "cause" as a separate requirement in its 2016 contract-law reform, keeping similar protection through other rules, and Germany's BGB needs neither consideration nor cause. Everywhere, a bare promise to give something away needs a formal act: a deed in England, a notary in Germany (BGB §518). Interactive · The contract checker Sell a bike for 100 Promise a friend a gift Pay for last week's help Accept but change the price Deal to rob a bank Gift of a house, signed deed Offer made Accepted on the same terms Both adults of sound mind Lawful purpose Signed deed / notary Something in return Nothing: a pure gift Thanks for a past favour A teaching model of the general rules described above, not the law of any single country; real codes add many form and exception rules. A company is a person, and limited liability moves the loss Run a business as yourself (a sole trader or ordinary partnership) and its debts are your debts, down to your savings and often your home. Register a company and the law creates a separate legal person that owns the assets and owes the debts. Shareholders can lose what they put in, but creditors generally cannot chase them personally. That is limited liability. The English House of Lords confirmed it in Salomon v A Salomon & Co (1897): a boot-maker who had turned his business into a company was not personally liable for its debts, because the company was "at law a different person altogether". The names change with the country: the UK private "Ltd", the US corporation or LLC, Germany's GmbH, France's SARL and SAS, Spain's S.L., Brazil's "Ltda.", and in Mexico the S.A. de C.V., the S. de R.L. de C.V. and, since 2016, the simplified S.A.S. Rules on capital differ: a German GmbH needs €25,000 of share capital (€12,500 paid in on registration), while its cheaper cousin the UG can start from €1. Banks often undo the shield by asking the owner for a personal guarantee on a loan, and courts may "pierce the veil" in cases of fraud. The shield protects against bad luck, not against wrongdoing. Interactive · Who pays when the business fails? Sole trader Limited company Money you put in Debts the business cannot pay Your personal assets Personal guarantee you signed Illustrative figures in any currency. Ignores veil-piercing, taxes and insolvency costs. Torts: owing care to strangers, and product liability A tort is a wrong done to someone you have no contract with. The great case is Donoghue v Stevenson (House of Lords, 1932): May Donoghue said a decomposed snail came out of an opaque ginger-beer bottle in a Paisley café. The facts were never tested in court, because the manufacturer died and the claim settled in 1934. But the ruling on the law stood: a manufacturer owes a duty of reasonable care to the final consumer, which Lord Atkin built on the idea of a "neighbour", someone you ought reasonably to have in mind. How much care is enough? Judge Learned Hand gave a famous rule of thumb in United States v. Carroll Towing (1947): you are negligent if the burden of the precaution (B) is less than the probability of the harm (P) times its size (L). Courts and juries seldom compute it, but it explains why a cheap fix for a deadly risk is a duty. Product liability goes further: in strict liability the question is not whether the maker was careful but whether the product was defective and caused harm. The EU's 1985 directive was strict; a new one (Directive 2024/2853) replaces it, explicitly covers software, and member states must write it into law by 9 December 2026. Interactive · Negligence or strict liability? Negligence (Hand rule) Strict liability Cost of the precaution (B) Chance the harm happens (P) Size of the harm (L) Product was defective Tort stories are often told wrong. In Liebeck v. McDonald's (1994), a 79-year-old woman suffered third-degree burns on 6% of her body, spent eight days in hospital for skin grafts, and the jury found her 20% at fault. It awarded $200,000 in compensation (reduced to $160,000) and $2.7 million in punitive damages, which the judge cut to $480,000, a total of $640,000. The parties then settled for an undisclosed sum. Not the "spilled coffee, millions" of the joke. Intellectual property: ideas are free, expressions and inventions are not Three main rights protect creations, and they protect different things. A patent protects a new, non-obvious invention for 20 years from filing (the international minimum in the TRIPS agreement; Mexico also uses 20), in exchange for publishing how it works. Copyright protects the particular expression of a work (a song, a book, source code) automatically, but never the bare idea; a boy-wizard-school premise belongs to everyone. A trademark protects a name or logo that tells buyers who made something, and can last indefinitely if renewed and used. A trade secret is no registered right at all: it lasts as long as you keep it secret and the law protects it against theft. Copyright terms are where countries differ most. The Berne Convention sets a floor of the author's life plus 50 years; the EU, UK and US use life plus 70; Colombia 80; Mexico 100 for works in copyright since 2003. So one author's work can be free to copy in one country and protected in another. In the US, the 1928 film that introduced Mickey Mouse, Steamboat Willie, entered the public domain on 1 January 2024; only that early version, not the modern character. Interactive · Which right protects it? Patent Copyright Trademark Trade secret None Next item Author died in Terms for works by individual authors in countries with the standard rules; older works, anonymous works and recent changes can differ. The public-domain year is the 1 January after the term ends. Employment: "at will" is the exception, not the rule In the US the default is at-will employment: an employer can end a job at any time for almost any reason, and an employee can quit likewise. Only Montana, since its 1987 Wrongful Discharge from Employment Act, requires good cause after a probation period. There are exceptions everywhere in the US (discrimination, retaliation, union and implied contracts), but no general severance pay by federal law. Most of the rest of the world sits at the other end: dismissal needs a recognised reason, notice, and often payment. The EU has no single dismissal law, only minimum rules (for example on collective redundancies), so each country keeps its own. The UK sits in between. After a qualifying period, unfair dismissal is a claim; the Employment Rights Act 2025 (royal assent 18 December 2025) lowers that period to six months, though its provisions come in stages. Germany's protection law offers a statutory option of half a month's pay per year of service in certain redundancy dismissals (§1a KSchG). France sets a minimum legal dismissal payment of a quarter of a month's pay per year, rising to a third beyond ten years, after eight months' service. Spain's unfair-dismissal compensation is 33 days per year, capped at 24 months. Mexico's federal labour law ties an unjustified dismissal to a constitutional indemnity of three months' wages plus further amounts per year of service. These are floors that depend on circumstances; check the current text. Interactive · What does losing a job cost the employer? Years of service Monthly gross pay Formulas for one narrow case in each country (see text); illustrative, in any currency. Real cases depend on contract, sector, collective agreements and the court. Who the board answers to: fiduciary duty and the stakeholder debate Directors and managers hold power over other people's money, so the law gives them fiduciary duties. In the common-law world the two classics are the duty of care (decide with reasonable information and attention) and the duty of loyalty (do not put your own interest ahead of the company's). Courts are slow to second-guess honest decisions: the business judgment rule protects a board that acted informed and in good faith, even when the result was bad. Loyalty breaches, like self-dealing, get far less slack. To whom is the duty owed? Shareholder primacy says the owners, who bear the residual risk; Milton Friedman put it in a 1970 New York Times Magazine essay: the social responsibility of business is to increase its profits within the law. The case people cite for it, Dodge v. Ford (Michigan, 1919), did order Ford to pay an extra dividend of $19.3 million, but the line about running a corporation for shareholders' profit is obiter dictum, and scholars such as Lynn Stout argue it is misread as a binding rule. Stakeholder views say employees, customers, suppliers and communities count too. The UK's Companies Act 2006 (s.172) says directors act for the members' benefit while "having regard" to such interests. Germany's 1976 law gives employees half the seats on the supervisory board of companies with more than 2,000 employees. In 2019 the US Business Roundtable statement, signed by 181 chief executives, committed to all stakeholders; critics have argued that this changed little in practice. Scholars still disagree; both sides have serious arguments. Ethics cases, told correctly Ethics asks what you should do where the law is silent or lets you. The famous cases teach most when the myth is separated from the record. CaseWhat is establishedWhat is told wrong or still disputed Ford Pinto, 1970sA 1973 Ford report weighed about $11 per vehicle for fuel-system fixes against valued deaths (about $200,000 each). In Grimshaw v. Ford the jury awarded $127.8 million; the judge cut the punitive part to $3.5 million. Ford recalled about 1.5 million cars in 1978.The memo covered all manufacturers and a federal rule, not Ford's own lawsuit costs. Magazine claims of 500 to 900 deaths are unsupported; Gary Schwartz argued the Pinto's fire record was about average for its class. Tylenol, 1982Seven people died from poisoned capsules in Chicago. Johnson & Johnson recalled about 31 million bottles and reissued the product in tamper-resistant packs; share fell from 35% to 8% and recovered in about a year.Nobody was ever charged with the poisonings. The case is a model of putting safety before sales, but the company was acting under heavy public and regulatory pressure. Volkswagen, 2015Software detected emissions tests and switched controls on only then; about 11 million cars worldwide. VW's total global cost reached about $33 billion by mid-2020.Who at the company knew, and when, is still being settled in court in several countries. Sources: see Sources & Further Reading. What a graduate just sees A promise binds only when it fits the legal recipe, and the recipe differs by family: consideration in common law, cause or form in many civil codes. Before arguing "who is right", ask "which law applies, and which court?" A company is a separate person; limited liability moves loss from owners to creditors, which is why lenders ask for guarantees. Negligence asks whether you were careful; strict liability asks whether the product was defective. Ideas are free; expression, inventions and brands are protected for different times, and trade secrets only while secret. US at-will employment is the outlier; most countries require reasons, notice or payment. Directors owe duties of care and loyalty; courts rarely punish honest mistakes but punish self-dealing. "Legal" and "right" are different questions, and a viral scandal story usually has a documented version that is more interesting. Where it shows up next Strategy & Competition (34/54): antitrust law is the legal limit on how far strategy can go. Entrepreneurship (34/56): choosing a company form, shareholder agreements, IP and employment contracts are the first legal decisions of any startup. Corporate Finance (34/51): limited liability and debt priority are what make creditors price risk. In the world: compliance jobs, in-house counsel, procurement, HR, and any founder signing a first lease. If you want to go deeper 📘 Textbook. Clarkson, Miller and Cross, Business Law: Text and Cases (Cengage, many editions). Widely assigned US business law course text with cases. 📘 Textbook. Constance Bagley, Managers and the Legal Environment (Cengage). Written for managers and used on business-school courses. 📘 Across countries. Zweigert and Kötz, An Introduction to Comparative Law (3rd ed., Oxford, 1998), and H. Patrick Glenn, Legal Traditions of the World (5th ed., Oxford, 2014). 📘 Gentler. Jay Feinman, Law 101 (Oxford). An accessible tour of the US system. 🌐 Free course (ethics half). Michael Sandel's Justice course from Harvard, eight lectures online. The takeaway Law is a set of recipes for who is bound, who is liable and who answers to whom, and the recipes are written differently in common-law, civil-law and EU systems. A business student learns the recipes that decide who bears the loss: the contract, the company, the product, the job and the board. Try this: take one agreement you accepted this week (a lease, a phone contract, an app's terms). Find who the parties are, what each gives, and what happens if one stops. Sources & Further Reading Sources. Legal families, precedent, Costa v ENEL (15 July 1964) and Van Gend en Loos (1963): standard comparative-law accounts (Zweigert & Kötz; Glenn). Consideration, past consideration and Pao On v Lau Yiu Long: standard English contract law. Chile Código Civil art. 1445 (capacity, consent, lawful object, lawful cause): Biblioteca del Congreso Nacional. Spain Código Civil art. 1274 (cause in remuneratory contracts) and France's 2016 reform removing "cause" as a separate validity condition: stated as the reform is commonly described, not re-checked against the primary text in this session. Salomon v Salomon [1897] AC 22 (House of Lords, 16 November 1897). GmbH €25,000 capital, UG from €1: German GmbH law. Donoghue v Stevenson [1932] AC 562; facts never proven, settlement 1934. United States v. Carroll Towing (2d Cir. 1947). EU Directive 2024/2853 (adopted 23 October 2024; transposition deadline 9 December 2026) replacing Directive 85/374/EEC. Liebeck v. McDonald's: figures from court and press records as summarised in standard references. Patents 20 years: TRIPS; copyright terms by country: Berne Convention minimum 50 years, national laws (EU, UK, US 70; Colombia 80; Mexico 100). Steamboat Willie entered the US public domain 1 January 2024. Montana Wrongful Discharge from Employment Act 1987. UK Employment Rights Act 2025 (royal assent 18 December 2025; six-month qualifying period, commencement staged). KSchG §1a (half a month's pay per year); France service-public.gouv.fr (legal dismissal pay, 8 months' service); Spain Estatuto de los Trabajadores art. 56 (33 days per year, 24-month cap, as commonly stated). Mexico's three months plus per-year amounts: from the constitutional and labour-law framework; confirm in the current Ley Federal del Trabajo. Dodge v. Ford (Mich. 1919); Friedman, New York Times Magazine, 13 September 1970; Companies Act 2006 s.172; Mitbestimmungsgesetz 1976; Business Roundtable statement, August 2019. Ford Pinto: Grimshaw v. Ford (1978); Gary Schwartz, "The Myth of the Ford Pinto Case", Rutgers Law Review (1991). Tylenol: 1982 recall of about 31 million bottles. Volkswagen: 2015 EPA notice; cost figure as of June 2020. Every number in the interactives was computed in node (see the formulas in the text). 🌐 Harvard Justice with Michael Sandel 📘 Zweigert & Kötz, An Introduction to Comparative Law 📘 Glenn, Legal Traditions of the World 📘 Clarkson, Miller & Cross, Business Law: Text and Cases Step 14. Microeconomics: Why Nothing Is Free and Every Price Is a Message ------------------------------------------------------------------------- Why: Law and economics starts with incentives. Everything costs what you gave up, choices happen one step at a time, and a price is the signal that makes strangers cooperate. Until it is wrong, and then you can see exactly how wrong. A coffee shop raises its flat white from 3.50 to 3.80 and, somehow, still looks busy. A ride-hailing app doubles its fares in the rain and, ten minutes later, there are more cars on the road. A city starts charging drivers to enter its centre, and the jam thins out without a single new rule about who may drive. Nobody commanded any of this. A price moved, and thousands of people each did a small, selfish, sensible thing. An economics graduate watches those three scenes and sees the same few ideas working: everything costs something you gave up, decisions happen one step at a time, and a price is a signal that tells buyers to hold back and sellers to show up. That toolkit is microeconomics: how individuals and firms choose, and what happens when those choices meet in a market. It is also the friendliest door into the whole subject, because you already use it every time you shop. The course in one box Who takes itEveryone on an economics, business or marketing degree, usually in year 1 as "principles" and again in year 2 as "intermediate microeconomics", with calculus. MIT puts its principles course (14.01) at the gateway to Course 14-1; business schools such as Wharton teach the same toolkit as "managerial economics". What it is forPredicting how people and firms respond when prices, taxes, rules or competitors change, and judging whether the result is good for anyone besides the people making the trade. Comes afterCalculus I (34/01): "one more" is a derivative. Leads toMacroeconomics (34/43), Game Theory (34/45), Behavioral Economics (34/46), International Trade & Finance (34/47), Public Economics (34/49), Strategy & Competition (34/54), Marketing Management (34/57) and Pricing (34/61). What this piece gives youYou won't be able to estimate a demand curve from real data. You will see why a price cap makes queues, why a tax costs more than it raises, and why a market with five firms behaves differently from one with one. Easier first reads: Where Money Actually Comes From (04/02), Pricing Without Fear (04/03) and Capitalism: How Markets, Prices and Private Property Organise an Economy (31/01). This one puts numbers and sliders on the same ground. All the markets below are illustrative, not data. Scarcity and opportunity cost: the real price is what you give up Wants have no ceiling; time, land, labour and money do. That gap is scarcity, and it makes every choice a trade. The honest price of anything is its opportunity cost: the best thing you gave up to get it. A two-hour film costs the ticket plus whatever else those two hours could have been. A university degree's biggest cost is often the wages you didn't earn. Economists draw this as a production possibilities frontier: the most of one good you can make for each amount of another. It bows outward because resources aren't equally good at everything. The first fields moved from wool to wheat are the ones best suited to wheat; the last fields are poor wheat land. So each extra unit costs more than the one before. This rising cost, not any law of nature, is what lets prices carry information. Interactive · A farm's frontier Wheat grown Illustrative farm: wool = 100 − wheat²/100. The cost of the next unit is wool(now) − wool(after one more wheat). At 40 wheat the farm can have 84 wool. One more wheat costs 0.81 wool. At 80 wheat the same extra unit costs 1.61 wool, twice as much. Nothing got worse; you just ran out of the easy fields. Remember this shape whenever someone says "just do more of it". Thinking at the margin: only the next unit matters People rarely choose all or nothing. They choose one more: one more hour of study, one more loaf baked, one more floor on the building. The margin is the edge where the decision lives. The rule an economics graduate carries: keep doing something while its marginal benefit is at least its marginal cost, and stop when the next unit would cost more than it brings in. do more while marginal benefit ≥ marginal costfor a seller facing a market price, marginal benefit is just the price A bakery sells loaves at a fixed price. Its cost of the next loaf rises as the oven gets crowded and staff go onto overtime (an illustration, not a real bakery). The slider below is the owner's decision. Watch the profit hump: the top is exactly where the cost of the next loaf meets the price. Interactive · How many loaves? Price per loaf Loaves baked Illustrative: total cost = q + 0.05q², so the next loaf costs about 1 + 0.1q. At a price of 6 the best output is 50 loaves and profit is 125. At 40 loaves the owner is leaving money on the table; at 60 she is baking loaves that cost more than they sell for. A higher price pushes the best output up: at 10 it is 90. Lining up each price with its best output is exactly how a supply curve is built. Supply and demand: the price that clears the market Demand says that, other things equal, buyers want less as the price rises. Supply says that sellers offer more as it rises (the bakery just showed why). Draw both against price and they cross at one point: the equilibrium price, where the quantity buyers want equals the quantity sellers offer. Above it there is a surplus and sellers cut prices; below it there is a shortage and buyers bid up. The price is pulled to the crossing without anyone setting it. The key habit: separate moving along a curve (the price changed) from shifting it (something else changed: tastes, income, input costs, a frost). Try three shocks in a market whose starting point is price 30, quantity 40. Interactive · Shift the curves Reset Demand rises (a fad) Supply falls (a frost) Both Demand shift (units at every price) Supply shift (units at every price) Illustrative: demand Q = 100 − 2P, supply Q = 2P − 20, then shifted sideways. A fad lifts both price (35) and quantity (50). A frost lifts the price to the same 35 but cuts the quantity to 30. Same price, opposite quantities: a graduate reads the quantity to tell whether demand or supply moved. When both shift by 20 the price jumps to 40 and the quantity barely changes, because the two effects on quantity cancel. Elasticity: how loudly buyers react A price rise always lowers the quantity demanded. The question that matters is how much. Price elasticity of demand is the percentage fall in quantity for a 1% rise in price. If it is below 1 in size, demand is inelastic: buyers shrug (salt, insulin, petrol in the short run). If it is above 1, demand is elastic: buyers walk (one brand of cereal, a restaurant meal). elasticity = % change in quantity ÷ % change in pricesellers' revenue rises with price when demand is inelastic, and falls when it is elastic A real case: from January 2014 Mexico taxed sugary drinks at one peso a litre, commonly described as roughly a tenth of the price. Purchases of the taxed drinks fell about 6% over 2014, and about 9% in the lowest-income households (Colchero and colleagues, BMJ, 2016). If the whole tax reached shelf prices, that is an elasticity around 0.6: buyers responded, but less than one-for-one. It is a rough reading, since pass-through to prices varied. Interactive · What does a 10% price rise do? Staple (0.3) Unit elastic (1) Restaurant meal (2) One brand (3) Elasticity (size) Price Illustrative constant-elasticity demand: Q = 100 × (P ÷ 10)−e. Real elasticities differ by market, time horizon and how many substitutes exist. With elasticity 0.5, a 10% price rise cuts quantity by about 4.7% and raises revenue by about 4.9%. At 2, the same rise cuts quantity by 17.4% and revenue by 9.1%. That is why a monopolist never charges where demand is inelastic: it could earn more by charging more. Surplus and the triangle nobody gets A trade happens only if it makes both sides better off. Consumer surplus is the gap between what a buyer would have paid and what they did pay. Producer surplus is the gap between what a seller received and the least they would have taken. In the market above, each is worth 400, so the total is 800. A competitive market, left alone and free of side effects, produces exactly the trades that make that total as large as it can be. Now interfere. A tax drives a wedge between what buyers pay and sellers keep, so some trades that were worth doing no longer happen. A price ceiling below the equilibrium makes sellers supply less than buyers want. Either way the lost trades are the deadweight loss: surplus that went to nobody. It is a triangle, so it grows with the square of the wedge. Interactive · A tax, or a price cap Tax per unit Price ceiling Tax per unit Same market as above (price 30, quantity 40, surplus 800). For the cap, the best case is assumed: the buyers who value the good most get it. Real rationing is usually worse. A tax of 10 shrinks the quantity from 40 to 30, raises 300, and destroys 50 of surplus. Double the tax to 20 and the deadweight loss does not double, it quadruples to 200, while revenue rises only to 400. A ceiling at 20 leaves 20 units on sale where buyers want 60: a shortage of 40, a loss of 200 even in the best case, and an invitation to queue, bribe or build a black market. Note what a tax can do that a cap cannot: it raises money that can be spent. The next piece in this thread, Public Economics (34/49), is about who ends up actually paying it. Market structures: from a thousand sellers to one "Supply and demand" assumes sellers are too small to move the price. That holds for a farmer selling wheat, not for an electricity grid or a search engine. Economists line up a spectrum. At one end is perfect competition: many sellers, identical goods, so each takes the price as given and price is driven to marginal cost. At the other is monopoly: one seller, who can choose the price, and who restricts quantity to keep it high. In between are oligopoly (a few firms who watch each other) and monopolistic competition (many firms with slightly different products, like restaurants). The simplest model that shows the whole spectrum is Cournot's, from 1838: firms choose quantities, each knowing the others do the same. The more firms, the more each fears flooding the market, and the closer price falls to cost. Interactive · How many rivals? Firms compete on quantity Perfect competition Number of firms Illustrative: demand P = 100 − Q, each firm's marginal cost 20. One firm sets 40 units at 60. Cournot with n firms: Q = 80n ÷ (n+1). One firm charges 60 and sells 40; two firms get 46.7; five get 33.3; twenty get 23.8, nearly the competitive 20. Buyers gain as firms are added (consumer surplus goes from 800 with one firm to about 2,900 with twenty), and the deadweight loss shrinks from 800 to about 7. This is the economic case for competition policy, and the reason Strategy & Competition (34/54) is a whole course. Entry matters more than the headcount, though: a market with one firm but easy entry can behave better than a market with three that are protected. Externalities and public goods: when prices miss something Prices work when the buyer and seller bear all the costs and benefits of the trade. An externality is a cost or benefit that lands on someone else: smoke from a factory, a neighbour's loud party, or, on the good side, a beekeeper's bees pollinating the orchard next door. The market quantity is too high for harms and too low for benefits, because the decision-maker ignores the third party. The classic fix is a Pigouvian tax (A. C. Pigou, 1920): charge the polluter the damage they cause, so the private price includes the social cost. London's congestion charge, which began on 17 February 2003 at five pounds a day (the standard rate is now £18 as of January 2026), is a price on road space for exactly this reason. Ronald Coase argued in 1960 that, where bargaining is cheap and rights are clear, the parties can sort it out themselves with no tax at all. Both are alive in every environmental debate. Interactive · A factory that pollutes Damage per unit made, to neighbours No policy Tax equal to the damage Same market as before. Making each unit costs the neighbours the amount on the slider. With damage of 10 per unit, the market still makes 40 units but the best quantity is 30. The ten extra units each cost society more than they are worth: a loss of 50. A tax of 10 moves the market to exactly 30. The other kind of miss is a public good: something nobody can be excluded from and that one person's use doesn't use up (a lighthouse, clean air, a vaccine's herd effect). Each person would like someone else to pay, so private markets undersupply it. When a resource is shared but rivalrous, a commons, Garrett Hardin's 1968 "tragedy of the commons" warned of overuse. Elinor Ostrom's field work, in Governing the Commons (1990) and her 2009 Nobel Prize, showed that communities from Swiss pastures to fisheries often build rules that avoid it without privatising or handing it to the state. The honest version is "it depends on the rules". More on this in Public Economics (34/49). What a graduate just sees Every choice has an opportunity cost, and it usually rises: the first unit is cheap, the thousandth is not. Decisions happen at the margin. Sunk costs and averages are the wrong numbers to look at. A price is information. When it moves, ask which curve shifted, and read the quantity to tell. Whether a price rise helps a seller depends on elasticity, which depends on substitutes and time. A price cap makes a shortage and a tax makes a wedge; the deadweight loss grows with the square of the wedge. "More competitors" and "freer entry" push price toward cost; fewer push it away. When someone else bears the cost or gets the benefit, the market quantity is wrong, and the fix is to make the price carry it. Markets can fail, but "the government fixes it" is a claim to check too: compare real alternatives, not an ideal against a market. Where it shows up next Macroeconomics (34/43): the same supply-and-demand logic, scaled up to the price level, interest rates and the whole labour market. Game Theory (34/45): when the firm count is small, strategy replaces the price-taking assumption. The oligopoly dial above is a simple game. Public Economics (34/49): externalities, public goods and who bears a tax become the whole subject. In the world: a surge price on a ride app, a carbon price, a minimum wage debate, antitrust cases against big platforms, and every "should we charge for this?" meeting in a company. If you want to go deeper 📘 Textbook. N. Gregory Mankiw, Principles of Microeconomics (Cengage). The most widely assigned introduction in the US and much of the world: clear, short chapters. 📘 Textbook. Daron Acemoglu, David Laibson and John List, Economics (Pearson), or Paul Krugman and Robin Wells, Microeconomics (Worth). Two modern alternatives: the first leans on evidence and experiments. 📘 Gentler. Charles Wheelan, Naked Economics (W. W. Norton). Almost no maths; the ideas as stories. 🌐 Free course. MIT OpenCourseWare 14.01 Principles of Microeconomics (Fall 2023): lectures and problem sets. Also CORE Econ's The Economy and Khan Academy Microeconomics, both free. The takeaway Every choice costs the best alternative you gave up, and it is made one step at a time. Prices carry that cost between strangers: when they are right, markets turn scattered selfishness into trades that make both sides better off. When they are wrong (a cap, a tax, a monopolist, a neighbour who bears the smoke), something is lost, and the skill is to find which wedge is the problem. Try this: this week, price one thing you buy in terms of what you gave up, and find your margin. Would you pay for one more? Then watch a price move at a shop or an app and ask which curve shifted. Sources & Further Reading Sources. The ideas are standard textbook microeconomics (Mankiw; Acemoglu, Laibson and List). Every number in the interactives uses invented, illustrative markets and was computed in node: farm frontier 84 to 83.19 (cost 0.81) at 40 wheat and 36 to 34.39 (1.61) at 80; bakery best output 50 with profit 125 at price 6, 90 at price 10; equilibrium 30 and 40, shocks 35 and 50 (fad), 35 and 30 (frost), 40 and 40 (both); elasticity 0.5 gives −4.65% quantity and +4.88% revenue, elasticity 2 gives −17.36% and −9.09%; tax of 10 gives quantity 30, revenue 300, deadweight loss 50, tax 20 gives 200 and revenue 400; ceiling 20 gives quantity 20, shortage 40, loss 200; Cournot with 1, 2, 5, 20 firms gives price 60, 46.7, 33.3, 23.8 and consumer surplus 800 to about 2,900; externality of 10 gives optimum 30 and loss 50. Mexico's 2014 sugary-drink tax: Colchero, Popkin, Rivera and Ng, BMJ 352:h6704 (2016), which reports a 6% fall in taxed-drink purchases in 2014 and 9% in the lowest-income households; the one-peso-a-litre rate is as reported in public summaries and the "about a tenth of the price" is approximate. London congestion charge: began 17 February 2003 at £5, £18 from 2 January 2026 (Transport for London, via Wikipedia). Coase 1960 (Nobel 1991), Pigou 1920, Hardin 1968 (Science), Ostrom 1990 (Nobel 2009), Cournot 1838 are standard history of economic thought. 🌐 MIT OCW 14.01 Principles of Microeconomics 🌐 CORE Econ, The Economy 📘 Mankiw, Principles of Microeconomics 📘 Wheelan, Naked Economics Step 15. Game Theory: When Your Best Move Depends on Mine --------------------------------------------------------- Why: Settlement, bargaining and strategy. Two shops pick prices, two countries pick tariffs, a hundred bidders pick bids. Game theory is the maths of choosing when everyone else is choosing too, and it explains why smart people can trap themselves. Two petrol stations face each other across a road. If both charge a fair price, both make a decent profit. If one cuts its price, it steals the customers and makes more, for a while. So each is tempted to cut. Both cut. Both now earn less than before, and neither can raise prices alone without losing everyone. Nobody was stupid. Each did the sensible thing given what the other might do. That pattern, a trap built entirely out of sensible choices, is the first thing game theory teaches you to see. It then teaches how to get out of the trap: by repeating the game, by changing who moves first, by changing the rules. The same toolkit explains the design of radio-spectrum auctions and the matching of kidney donors. The course in one box Who takes itEconomics majors in year 2, straight after microeconomics. Business schools teach it inside strategy courses, and computer science and political science programmes teach it too, because algorithms and elections are games. What it is forPredicting what rational, self-interested players will do when each one's best move depends on the others, and designing rules so the result is a good one. Comes afterMicroeconomics (34/42). Leads toStrategy & Competition (34/54); it also underlies the auctions and pricing in Pricing (34/61) and the rules-of-the-game thinking in Public Economics (34/49). What this piece gives youYou will not be able to solve a multi-stage game with incomplete information. You will see why a dominant strategy can leave everyone worse off, why a threat only works if carrying it out is in your interest, and why an auction format changes how people bid. Easier first reads: the library's The Social Contract (18/14) asks why we accept rules and a state at all, and Anarchism (31/04) covers the commons problem in words. This piece puts numbers on that kind of trap. Players, strategies, payoffs, and the Nash equilibrium A game has three ingredients: the players (who decides), the strategies (what each can do) and the payoffs (what each gets for every combination of choices, in whatever they care about: money, time, votes, survival). Two players with two options each fit in a small grid, the payoff matrix. One player picks the row, the other the column, and each cell holds two numbers: the row player's payoff first, the column player's second. Two ideas solve most such grids. A dominant strategy is one that is best for you whatever the other does: if it exists, play it. When neither player has one, look for a Nash equilibrium: a pair of choices where neither player could do better by changing their own choice alone. John Nash proved in 1950 that every finite game has at least one, possibly in mixed strategies (rolling dice between options). Nash shared the 1994 economics Nobel prize with John Harsanyi and Reinhard Selten for it. Nash equilibrium: each player's choice is a best response to the other'snobody gains by switching alone; it says nothing about whether the outcome is good Interactive · The payoff-matrix workbench Prisoner's dilemma Stag hunt Chicken Matching pennies Which side to drive Each cell: your payoff (row player), then the column player's. Edit the numbers; the analysis updates. Shaded = a best response for that player; outlined cell = Nash equilibrium. Without JavaScript: in the prisoner's dilemma (5, 3, 1, 0), defecting is dominant for both players, the only Nash equilibrium is both defecting for 1 each, and both cooperating would give 3 each. Try the presets and read the verdicts. Chicken and the driving game have two pure equilibria and a mixed one at 50:50; matching pennies has no pure equilibrium at all, only the mixed one, which is why a goalkeeper and a penalty-taker must be unpredictable. In matching pennies, if the row player leans even slightly toward heads, the column player exploits it. The prisoner's dilemma: why smart players choose badly Merrill Flood and Melvin Dresher devised it at the RAND Corporation in 1950, and Albert Tucker gave it its story: two suspects, questioned separately. Stay silent (cooperate) and both get a light sentence. Betray the other (defect) and you walk free while he gets the worst. Both betray and both get a heavy sentence. With points instead of years, the standard payoffs are: temptation 5, mutual cooperation 3, mutual defection 1, being betrayed 0. Whatever the other does, defecting pays you more: 5 beats 3 if she cooperates, 1 beats 0 if she defects. So both defect and both get 1, when both cooperating would have given 3 each. The equilibrium is stable and bad. That is the logic of arms races, overfishing, price wars and the two petrol stations. Now play it. Ten rounds against a computer opponent whose rule you can pick; you know the game is exactly ten rounds long. Interactive · Play ten rounds Tit for tat Always defect Always cooperate Grudger Coin flip CooperateDefectRestart Payoffs per round: both cooperate 3 each; you defect on a cooperator 5 to 0; both defect 1 each. Tit for tat copies your last move; the grudger cooperates until you defect once, then never again. Against tit for tat, the best ten-round total is 32: cooperate nine times, defect on the last round when it can no longer be punished. Against always-defect, nothing beats 10. Against always-cooperate you can take 50. The right play depends on who is on the other side, which is the whole subject in one sentence. Repeated games: when tomorrow changes today Meet the same person again and again and the logic changes: defecting today invites revenge tomorrow. In 1980 the political scientist Robert Axelrod invited game theorists to send in programs for a repeated prisoner's dilemma, each program playing every other for 200 moves. The winner, in this tournament and in a second, larger one, was the simplest entry: tit for tat, sent by the psychologist and game theorist Anatol Rapoport. It cooperates first, then copies the opponent's last move. Axelrod's 1984 book The Evolution of Cooperation drew the lesson: successful strategies were nice (never defect first), provocable (punish defection at once), forgiving (return to cooperation) and clear (easy to read). Tit for tat never beats the partner it faces; the best it can do in a single match is tie. It won by getting good scores out of nearly everyone. Run your own small tournament. Six kinds of players meet in a 200-round round robin; add copies of Always-defect and see whether the winner changes. Interactive · A round-robin tournament (a toy field) Always-defect entrants No mistakes 5% of moves slip Entrants: Always cooperate, Tit for tat, Grudger, Pavlov (cooperate only if both did the same last round), Coin flip, plus the Always-defect copies. Everyone meets everyone else for 200 rounds; bars show the average points per round. Payoffs 5, 3, 1, 0. A toy field, far smaller than Axelrod's. With no Always-defect, the nice, retaliating strategies fill the top. Add more defectors and the field gets harsher: the defectors climb to the top once enough naive cooperators and coin-flippers are there to be exploited, while their scores against each other stay at 1. Success in a repeated game depends on who else is playing. Turn on the 5% slips and tit for tat loses ground too: after one accidental defection two tit-for-tat players can lock into a spiral of mutual retaliation. Later work found more forgiving variants, such as generous tit for tat, and the Pavlov rule do better in noisy worlds. Cooperation without a referee needs a future worth protecting, which is why long-term relationships, reputations and repeated dealings support trust that one-off meetings cannot. Coordination games: when you just need to match Not every game is a conflict. In the driving game, both of you want to pick the same side; which side hardly matters. Load "Which side to drive" above: two equilibria, both good, and nothing in the payoffs says which. Conventions (driving on the left in the UK, Japan and India, on the right in most of the rest of the world) are equilibria picked by history. The stag hunt adds risk: both hunting stag gives 4 each, but hunting hare alone is safe at 3. Two equilibria again, one better but riskier. Thomas Schelling, in The Strategy of Conflict (1960), noticed that when payoffs cannot choose, players use focal points: the obvious, salient option, like meeting "at the clock" in a station. Many real-world failures, from bank runs to standards wars, are coordination games stuck on the bad equilibrium. Sequential games: the credible threat When players move in turn, you solve the game backwards: start at the end, see what the last mover would do, and work back. Take a company deciding whether to enter a market held by an incumbent. The incumbent says: "If you enter, I'll start a price war." Should the entrant believe it? Only if fighting is actually best for the incumbent after entry happens. If, once the entrant is in, the war would cost the incumbent more than sharing the market, the threat is empty. A rational entrant sees that and enters. Reinhard Selten's refinement of Nash equilibrium, subgame-perfect equilibrium, rules such empty threats out. Interactive · Entry, threats and commitment Incumbent's profit if it fights after entry No commitment Commit to fight (contract penalty) Payoffs (entrant, incumbent): stay out (0, 10); enter and incumbent accommodates (4, 5); enter and incumbent fights (−2, your slider). The commitment option makes accommodating cost the incumbent 3 (so it pays only 2). The slider has a threshold. With a war worth less than 5 to the incumbent, the threat is empty and the entrant walks in. Raise the war's payoff above 5, or use the commitment button, and the threat becomes credible, the entrant stays out, and the incumbent never has to fight. Commitment devices (spare factory capacity already built, a contract that punishes backing down, a reputation) have this strange property: by taking away your own options they can make you better off. Auctions: bid your value, or shave it An auction is a game where the rules decide the payoffs. In a sealed-bid second-price auction, the highest bidder wins but pays only the second-highest bid. William Vickrey analysed it in 1961 (it had been used by stamp collectors since 1893). Here, bidding exactly your true value is a dominant strategy: bidding more risks paying above your value, bidding less risks losing an item you would have profited from. In a first-price auction you pay what you bid, so you shave your bid below your value, trading a bigger profit if you win against a smaller chance of winning. With four bidders whose values are equally likely to be anywhere in a range, the equilibrium bid is three-quarters of your value (in general, (n−1)/n of it). Interactive · Four bidders, two formats (3,000 simulated auctions) Your bid as a share of your value second-price   first-price Values for all four bidders are drawn uniformly between 0 and 100. The three rivals bid their full value in the second-price format and three-quarters of it in the first-price format. Your average profit is per auction, including those you lose. Slide the share. In the second-price format your profit peaks at 100% of your value; in the first-price format it peaks near 74%. Also watch the seller's average revenue: it is about 60 in both formats, a first glimpse of the revenue equivalence theorem. Real auctions differ from this textbook case. When bidders are unsure of the item's true value (oil leases, spectrum) the winner tends to be the one who overestimated most, the winner's curse. Mechanism design: design the game, then let people play it Game theory asks: given the rules, what will players do? Mechanism design turns it around: what rules would make self-interested players do what we want? Two famous cases. Spectrum auctions. Governments own radio frequencies and need to hand them to phone companies. For decades they used beauty contests and lotteries. From July 1994 the US Federal Communications Commission instead ran a "simultaneous multiple round" auction, where many related licences are sold together over many rounds and bidders see each other's bids. Theorists including Paul Milgrom and Robert Wilson helped shape the design, and they shared the 2020 economics Nobel prize for improvements to auction theory and new auction formats. In 2000 the UK's 3G auction raised £22.5 billion from five licences. Kidney exchange. Many people who need a kidney have a willing donor who is the wrong blood type. Selling kidneys is illegal almost everywhere, so prices cannot match people. Alvin Roth, Tayfun Sönmez and Utku Ünver designed algorithms (their 2004 paper in the Quarterly Journal of Economics) in which pair A's donor gives to pair B's patient while B's donor gives to A's: a swap, extended to longer cycles and to chains started by an altruistic donor. The first paired exchange recorded was in South Korea in 1991 and the first in the US in 2000; by 2012 the US National Kidney Registry had organised a 60-surgery chain, and by 2014 one of 70. Roth shared the 2012 economics Nobel prize with Lloyd Shapley for the theory of stable allocations and the practice of market design. Game theory predicts what people do under the rules. Mechanism design chooses the rules. What a graduate just sees Before asking what someone will do, ask what they would do if they expected you to do each of your options. A dominant strategy needs no guess about the other player. If it exists, it settles the game. A Nash equilibrium is stable, not good. The prisoner's dilemma's equilibrium leaves both worse off than cooperating. Repetition changes the game: cooperation can be rational when the future is long enough and defection is punishable. A threat counts only if carrying it out is in your interest when the time comes. Otherwise build a commitment or expect to be called. When payoffs do not choose between equilibria, the focal point does: salience, convention, a shared story. In a second-price auction, bid your value. In a first-price auction, shave your bid. The rules decide how people behave. When a market cannot use prices, you can still design the rules. Where it shows up next Strategy & Competition (34/54): firms setting prices, building capacity and deciding whether to enter are playing the games above. Pricing (34/61): discounts, price matching and surge pricing are games with customers and competitors. Behavioral Economics (34/46): the next piece asks when real people do not play the equilibrium, as in the ultimatum game. Machine Learning (34/32) and Computer Networks (34/27): game-playing AIs and congestion control both apply these ideas. In the world: online-advertising auctions, spectrum sales, school and hospital matching, climate treaties, arms control. If you want to go deeper 📘 Textbook. Robert Gibbons, Game Theory for Applied Economists (Princeton, 1992). Short and widely used in economics programmes. 📘 Textbook. Martin Osborne, An Introduction to Game Theory (Oxford). A fuller undergraduate treatment with many worked games. 📘 Gentler. Avinash Dixit and Barry Nalebuff, The Art of Strategy (Norton, 2008), and Robert Axelrod, The Evolution of Cooperation (1984). Real cases, almost no algebra. 🌐 Free course. Open Yale Courses ECON 159: Game Theory (Ben Polak, 24 lectures, recorded Fall 2007), covering Nash equilibrium, backward induction and signalling. The takeaway When your best move depends on others' moves, look for dominant strategies, then for equilibria, and remember that a stable outcome can be a bad one. Repetition, commitment and well-designed rules are the three ways out, and each is a way of changing the game rather than the players. Try this: this week, spot a situation where you and someone else are each waiting for the other to move first or to give in, and ask what the payoff grid looks like and whether it is a game you can change. Sources & Further Reading Sources. Dominance, Nash equilibrium, mixed strategies, backward induction and the second-price result are standard textbook game theory (Gibbons; Osborne; Polak's Yale lectures). The prisoner's dilemma was devised by Flood and Dresher at RAND in 1950 and named by Tucker (Wikipedia, "Prisoner's dilemma"). Nash, "Equilibrium points in n-person games," PNAS 36, 1950; the 1994 economics Nobel prize went to Nash, Harsanyi and Selten. Axelrod's tournaments (c. 1980) and 1984 book: tit for tat, by Anatol Rapoport, won both; matches were 200 moves; the death-spiral under noise and generous tit for tat are as described in Wikipedia's "Tit for tat". Schelling, The Strategy of Conflict (1960). The second-price auction was described by Vickrey in 1961 and used by stamp collectors from 1893. The FCC has held spectrum auctions since July 1994 using a simultaneous multiple round design; the UK's 2000 auction raised £22.5 billion from five 3G licences (Wikipedia, "Spectrum auction"). The 2020 prize went to Milgrom and Wilson, the 2012 prize to Roth and Shapley. Kidney exchange history from Wikipedia's "Kidney paired donation"; Roth, Sönmez & Ünver, "Kidney Exchange," QJE 2004. Every number an interactive shows was computed in node from the code on this page: ten-round best score against tit for tat 32, against always-defect 10, against always-cooperate 50; the four-bidder first-price optimum is near 0.74 (theory 0.75); the average winning price is near 60 in both formats; the toy tournament's ranking depends on the chosen field and is not Axelrod's result. 🌐 Open Yale Courses ECON 159 Game Theory 📘 Dixit & Nalebuff, The Art of Strategy 📘 Axelrod, The Evolution of Cooperation Step 16. Cognitive Psychology: A Narrow Beam and a Rebuilding Crew ------------------------------------------------------------------ Why: Why eyewitness memory fails. You attend to very little, hold about four chunks, and rebuild every memory as you use it. That design is clever, and it is why a confident witness can be sincerely wrong. You are sure you remember where you parked, who was at the party, which of two cars cut you off. You can see it. Then a photo, a receipt or another person disagrees, and the picture you were so sure of turns out to have been assembled, a little at a time, after the fact. Or: you are at a busy table, talking, and across the room someone says your name. You never heard the rest of that conversation, yet your own name pulled you out of this one. Or you try to keep a phone number in your head while a friend reads you another, and one of them simply vanishes. Cognitive psychology is the study of those ordinary moments: how a mind takes in a flood of input, keeps a little of it, stores a fraction of that, and rebuilds the rest on demand. A graduate stops trusting the feeling of "I clearly remember" and starts asking how the memory was built. This matters in classrooms, in cockpits, and, as we will see, in courtrooms. The course in one box Who takes itEvery psychology degree, usually in year 2. Neuroscience, linguistics, computer science (AI) and education majors take a version of it, and law students meet its memory half. What it is forExplaining how attention, memory, reasoning and language work, by experiments that time people, count their errors and compare conditions. Comes afterSensation & Perception (35/21), which itself needs Biological Psychology (35/20). Leads toDevelopmental Psychology (35/24), and beyond psychology to Behavioral Economics (34/46), Machine Learning (34/32) and, for lawyers, Civil Procedure & Evidence (35/08) and Criminal Law & Procedure (35/07). What this piece gives youYou will not be able to design an experiment, which is what Research Methods in Psychology (35/19) is for. You will have felt the limits of your own attention and memory on this page, and you will know why a confident eyewitness is not the same as an accurate one. Gentler first reads: Memory: How to Make Things Stick (17/04) and The Biases That Fool Everyone (17/02). The demos below are one-person toys timed on your device, not studies. Attention is a narrow beam, and most of the world falls outside it You are bombarded with far more than you can process, so the mind selects. In 1953 Colin Cherry played people two voices, one in each ear, and asked them to repeat one. They could, and could say almost nothing about the other voice, except that it was a voice, and that their own name, if it appeared there, often got through. Broadbent's 1958 filter model was the first answer: a bottleneck lets one channel through. Later models made the filter leakier, and the debate over how early or late the filter acts is still alive. The vivid modern version is inattentional blindness. In the famous 1999 "gorilla" experiment by Daniel Simons and Christopher Chabris, viewers counting basketball passes often failed to notice a person in a gorilla suit walking through the scene; in most groups about half missed it. Nothing is wrong with their eyes. What you see is what you attend to, and you cannot tell what you are missing, because the missing is not marked. The cleanest way to feel the limit is the Stroop effect (J. Ridley Stroop, 1935). Reading a word is so automatic that it intrudes when you try to name the colour of its ink. The conflict costs time you can measure. Interactive · Stroop on your own device Tap the colour of the ink, not the word. Six easy trials (word and ink agree), then six hard ones (they conflict). Your device times each tap. Ready? Start Press Start. A twelve-trial toy shows the effect for you. It is not a measurement of you, and timing on a phone screen adds noise. Most people are slower on the conflicting trials, often by a tenth of a second or more, and make more errors. Nothing "loaded" more information; two automatic processes simply fought over one response. A graduate carries the lesson everywhere: attention is a single narrow beam that can be split only at a cost, which is why a phone call hurts driving even when the phone is hands-free. Working memory holds about four chunks, not seven digits Hold a phone number in your head and you are using working memory: the scratchpad where you keep things while you use them. George Miller's 1956 paper "The Magical Number Seven, Plus or Minus Two" made 7 famous. Later work, above all Nelson Cowan's 2001 review, argued the true limit is nearer four chunks once you stop people from rehearsing and regrouping. The word that matters is chunk: a unit that is one thing to you. The letters F-B-I-C-I-A-N-A-S-A are ten items, or three chunks if you know the acronyms. Baddeley and Hitch (1974) described this scratchpad as a small set of parts, a loop for sounds, a sketchpad for pictures and a controller that directs attention. A graduate remembers the practical points. The store is small. It is easily overwritten. And the way out is not more effort but better chunking, which is why experts seem to have enormous memory in their own field, and ordinary memory outside it. Interactive · Digit span, with and without chunks One at a time In groups of three Digits to remember Ready? Show digits Check Pick a length and press Show digits. Digits are generated fresh each time, shown for 0.7 s each (groups get a longer pause between them). Try 7 plain, then 9 in threes. Most readers manage around six or seven plain digits and do noticeably better on longer strings when they are grouped, because three groups of three are three chunks. That is not a trick. It is the whole mechanism of memory improvement: the number stays small; the chunk gets bigger. Encoding and retrieval: what goes in decides what comes out Remembering has two halves. Encoding is how the information is processed on the way in; retrieval is how you get it back. In 1972 Fergus Craik and Robert Lockhart argued that deeper processing (what does this mean to me?) beats shallow processing (what does it look like?), and the result has held up well. A second idea, encoding specificity, says a cue works to the extent it matches how the memory was laid down. In a well-known 1975 study, Godden and Baddeley had divers learn word lists on land or underwater; words were recalled better in the place they were learned. The context effect is real but modest and not always found, so treat "study where you'll be tested" as a small bonus, not a rule. And then there is time. Hermann Ebbinghaus (1885) measured his own forgetting of nonsense syllables and found that loss is fastest at first and then flattens. A 2015 replication of his work (Murre & Dros) found the same shape. The graduate's practical conclusion is the spacing effect: reviewing something just as it begins to fade slows the next fall. The toy below uses a simple exponential model with made-up constants, so it shows the shape of the idea, not your forgetting. Interactive · Forgetting curve and review (illustrative model) No review One review, day 1 Days 1, 3, 7, 14 Model: retention = e−t/S. Start with S = 3 days (made up). Each review resets retention to 100% and multiplies S by 2.5 (also made up). Real forgetting depends on the material and the person. With no review, almost nothing is left by day 30 in this model (under 0.01%). With one review, about 2%. With four spaced reviews, about 87%. The numbers are invented; the reason spacing beats cramming is the finding. Memory is rebuilt each time, not replayed The folk picture is a video recording. The research picture, which goes back to Frederic Bartlett's 1932 Remembering, is a reconstruction: when you recall, you assemble the memory from fragments plus what you know about how things usually go. That makes memory efficient and error-prone, and the errors are not random. They move toward what makes sense. A neat way to see it is the paradigm that James Deese (1959) and Henry Roediger and Kathleen McDermott (1995) turned into a standard tool. Study a list of words that all circle one unlisted word, for example bed, rest, tired, dream, nap, then later say which words you saw. People often "recognise" the unlisted word, here sleep, nearly as readily as words that were really on the list. Try it. Interactive · A false memory, on demand Fifteen words appear, 1.2 s each. Then twelve words follow, one at a time; tap whether each was on the list. Ready? Start the list Was on the listWas not Press Start. The list is from the Roediger–McDermott (1995) study, built around the unlisted word "sleep". In the test, half the words were studied, two were unrelated, and two were related but not shown. The same machinery explains Elizabeth Loftus's best-known results. In 1974 Loftus and John Palmer showed people films of car crashes and then asked how fast the cars were going when they "smashed into" or "contacted" each other. The "smashed" group guessed about 41 mph; the "contacted" group about 32. A week later, those asked with "smashed" were more likely to report broken glass that was never in the film. In 1995 Loftus and Jacqueline Pickrell planted a false childhood memory of being lost in a shopping mall, and about a quarter of the 24 participants reported remembering it. Critics have noted that "remembering" in these studies is partial, and that planting a whole memory is harder than planting a detail. The settled point is narrower and still important: suggestion after the event can change what people report, and they can't feel the change. Eyewitnesses: sincere, confident and sometimes wrong This is where memory science meets the law. In the United States, the Innocence Project reports eyewitness misidentification in about 69% of the first 367 DNA exonerations it counts (the share was about 75% in older snapshots, when there were fewer cases). Countries differ in how they run and weigh identifications, but human memory is the same everywhere. The American National Academy of Sciences' 2014 report Identifying the Culprit reviewed the evidence and recommended practices such as blind lineup administration and recording how confident a witness is at the first identification. The fairest summary has two halves, and researchers disagree about their weights. Many studies show that confidence at trial, after months of repeated questioning, tells you little about accuracy. John Wixted and Gary Wells (2017) argued that the first confidence statement, from an uncontaminated lineup, is quite informative: high-confidence initial picks are usually right, and low-confidence picks often wrong. Both can be true, because "confident" at trial is not the same thing as "confident at the start". To see the structure, borrow signal detection theory. A witness gets a familiarity signal for each face. The culprit's signal is stronger by an amount d′ (sensitivity). The witness also has a bar (the criterion): how familiar a face must feel before they pick it. A lineup puts the possible culprit among five look-alike fillers. When the culprit is absent, a witness who feels pressure to choose will still choose. Interactive · A lineup, simulated 20,000 times Witness sensitivity d′ Bar for picking someone Toy model: six faces, equal-variance normal familiarity, the witness picks the most familiar face if it clears the bar. Culprit present and absent are equally likely. A real witness is messier. Notice what the sliders show. With d′ at 0, the witness knows nothing and the picks are noise. With a low bar, the witness picks someone nearly every time, and in culprit-absent lineups that someone is innocent. Raising the bar costs correct IDs but removes most of the false ones. That is why reformers focus on procedure: blind administration, fair fillers, and not telling the witness "good, you picked the suspect". Heuristics: fast rules that mostly work, and sometimes don't Amos Tversky and Daniel Kahneman's 1974 paper "Judgment under Uncertainty: Heuristics and Biases" showed that people judge probability by shortcuts. Availability: what comes easily to mind seems common, so after a news story people overestimate plane crashes. Representativeness: what resembles a type seems likely to belong to it, which is how the "Linda" problem (1983) leads many to rate "feminist bank teller" as more probable than "bank teller", though a subset can never be more probable than the whole. Anchoring: a number you've just heard drags your estimate toward it. Gerd Gigerenzer and others argue that heuristics are not just errors: in the right environment, simple rules do well, and the "biases" are partly artefacts of how problems are posed. Kahneman's side says the errors are systematic and costly. Both agree that the way you present numbers matters. A classic case from Tversky and Kahneman involves a witness again. Interactive · The taxi problem A cab hit a pedestrian at night. Some cabs in the city are Blue, the rest Green. A witness says the cab was Blue. Tested in similar light, the witness gets the colour right some of the time. Share of cabs that are Blue Witness accuracy Illustrative numbers; the 15% and 80% are the classic textbook version. Imagine 1,000 cabs and count. With 15% Blue cabs and an 80% accurate witness, the chance the cab really was Blue is about 41%, not 80%. Out of 1,000 cabs, 150 are Blue and the witness calls 120 of them Blue; of 850 Green cabs, the witness wrongly calls 170 Blue. So 120 of 290 "Blue" reports are right. In Tversky and Kahneman's report, most people answered near the witness's 80%, ignoring the base rate. Counting people instead of multiplying probabilities (Gigerenzer's "natural frequencies") makes the right answer much easier to find. Language and thought: does the word shape the idea? Edward Sapir and Benjamin Lee Whorf are credited with the idea that language shapes thought. The strong version, that you cannot think what you cannot say, has been rejected: people think about things for which they have no word, and babies think before they speak. The weak version, that language nudges attention and memory, has support. Berlin and Kay (1969) showed that colour terms across languages follow a near-universal order, suggesting biology constrains the vocabulary. And Winawer and colleagues (2007) found that Russian speakers, whose language has separate basic words for light blue (goluboy) and dark blue (siniy), were quicker to tell apart two blues that straddle that line, an advantage that vanished when they had to repeat a string of digits at the same time. Other claims, such as grammatical gender making speakers describe objects differently, are more contested, and several famous language-and-thought results have been hard to replicate. Say "language nudges" and stop there. The replication crisis touches this whole course. In 2015 the Open Science Collaboration tried to repeat 100 published psychology studies; about 97% of the originals had significant results and about 36% of the replications did. Cognitive-psychology effects, which are usually within-person and measured in milliseconds, fared better than social ones. Stroop, serial-position and false-memory effects replicate easily. Treat very large claims from small studies with caution, and see Research Methods in Psychology (35/19). What a graduate just sees Attention is a narrow beam: what you did not attend to is not "seen but forgotten", it was never stored. Working memory holds about four chunks. Better chunking, not harder trying, is how people hold more. How deeply you process something when it goes in decides how easily it comes out. Review at the edge of forgetting beats re-reading in one sitting. Recall is reconstruction. A vivid, detailed, confident memory can still be wrong. Questions asked after an event can change the memory without any feeling of change. A witness's accuracy depends on procedure: how the lineup was run and how soon confidence was recorded. When someone gives you a probability, ask for the base rate; count cases instead of multiplying fractions. Language nudges thought; it does not cage it. Where it shows up next Developmental Psychology (35/24): memory, attention and reasoning are not fixed. Children's working memory and theory of mind grow, and older adults' processing speed slows while vocabulary keeps growing. Behavioral Economics (34/46): the heuristics-and-biases programme is where much of the field began; its replication record is mixed, as the economics piece says. Machine Learning (34/32): human memory as a rebuild-from-cues system resembles models that fill gaps with likely content, which is both a strength and the source of confident errors. Law: Criminal Law & Procedure (35/07) and Civil Procedure & Evidence (35/08) meet eyewitness memory directly. Courts in different countries weigh identifications differently, and a number of jurisdictions have adopted lineup reforms. In the world: air traffic and cockpit design (attention and workload), interface design, teaching (spacing and retrieval practice), police interviewing, and the warnings on any "I remember it clearly" claim. If you want to go deeper 📘 Textbook. Michael Eysenck and Mark Keane, Cognitive Psychology: A Student's Handbook (Routledge / Psychology Press). A common UK and international choice, thorough and research-heavy. 📘 Textbook. Daniel Reisberg, Cognition: Exploring the Science of the Mind (W. W. Norton). A common US choice, easier on the first read. 📘 Gentler. Daniel Schacter, The Seven Sins of Memory (Houghton Mifflin, 2001), and Daniel Kahneman, Thinking, Fast and Slow (2011), noting that some priming studies in the latter did not replicate. Elizabeth Loftus's TED talk "The fiction of memory" is short. 🌐 Free course. MIT OpenCourseWare 9.00SC Introduction to Psychology (Fall 2011), whose lectures include memory and cognition; the free Noba chapters cover each topic here. The takeaway The mind is a narrow beam of attention, a four-chunk scratchpad and a long store that it rebuilds each time it is used. That design is efficient, and it means vividness and confidence are not evidence of accuracy. Good procedure, such as spaced review, blind lineups and counting cases instead of trusting a feeling, is how people protect themselves from their own minds. Try this: this week, when you are sure about a detail from last month, find something that can check it (a message, a photo, a receipt). Notice how often the gist is right and a detail has quietly moved. Sources & Further Reading Sources. Cherry 1953 and Broadbent 1958 (selective attention); Stroop 1935; Simons & Chabris 1999, Perception 28; Miller 1956, Psychological Review 63; Cowan 2001, Behavioral and Brain Sciences 24; Baddeley & Hitch 1974; Craik & Lockhart 1972; Godden & Baddeley 1975; Ebbinghaus 1885 and Murre & Dros 2015, PLoS ONE (replication); Bartlett 1932; Deese 1959 and Roediger & McDermott 1995, JEP: Learning, Memory, and Cognition 21; Loftus & Palmer 1974, Journal of Verbal Learning and Verbal Behavior 13 (mean estimates by verb: "smashed" about 41 mph, "contacted" about 32 mph); Loftus & Pickrell 1995, Psychiatric Annals 25 (24 participants, about a quarter reported the false event); Innocence Project (eyewitness misidentification in 69% of 367 DNA exonerations in its current count, earlier figure about 75%); National Research Council 2014, Identifying the Culprit; Wixted & Wells 2017, Psychological Science in the Public Interest 18; Tversky & Kahneman 1974, Science 185, and 1983 (Linda); Gigerenzer & Hoffrage 1995; Berlin & Kay 1969; Winawer et al. 2007, PNAS 104; Open Science Collaboration 2015, Science 349. Every number an interactive shows was computed in node: taxi problem 120/290 = 41.4%; lineup model at d′ 1.5, bar 1.5 gives 45% correct picks, 35% no pick when the culprit is present and a 5.5% innocent-suspect pick when absent; forgetting model, day 30: under 0.01% with no review, 2.1% with one review, 87.2% with reviews on days 1, 3, 7 and 14 (S grows from 3 to about 117 days). 🌐 MIT OCW 9.00SC Introduction to Psychology 🌐 Elizabeth Loftus, "The fiction of memory" (TED) 📘 Eysenck & Keane, Cognitive Psychology: A Student's Handbook 📘 Schacter, The Seven Sins of Memory This describes research, not medical or legal advice. If you are struggling with your memory, mood or wellbeing, a doctor or local service can help; findahelpline.com lists free helplines by country. Step 17. Public Policy: How Problems Become Policies, and What Then Goes Wrong ------------------------------------------------------------------------------ Why: How laws become policy and policy becomes law. A city charges fifteen cents for a plastic bag and the bags nearly vanish. A famous job-training scheme is announced with fanfare and fizzles in a maze of approvals. Public policy is the study of why the first happens, why the second is more common, and how to tell which is which. In March 2002 Ireland began charging shoppers 15 cents for every plastic bag at the till. Reports at the time, from the government and the press, said use fell by about 90 percent within weeks. Notice what did not happen: no inspector visited homes, no one was jailed, and nobody forbade bags. A small price, collected by the shop, changed what millions of people did without thinking about it. Now picture the opposite. A national programme is announced to create jobs in a poor district. Years later the money has been spent on meetings and approvals, and almost no jobs exist. Nobody lied, nobody stole. Every office that had to agree did agree, slowly and partly. A good idea met a long chain of people who each had other priorities. Public policy as a subject asks four things about any such case. Why did this problem get attention when others did not? What tool did the government choose, and why that one? Did the plan survive contact with the people who had to carry it out? And did it work, which means: compared with what would have happened anyway? The course in one box Who takes itPolitical science and public-affairs majors, usually in year 3. Schools of public policy (the Kennedy School, LSE, Sciences Po, the Hertie School and others) teach the same core as the heart of a master's degree, mixed with economics and statistics. What it is forUnderstanding how a social problem becomes a law, a tax or a programme, and judging whether that policy worked. Comes afterComparative Politics (35/13) and Public Economics (34/49). Leads toNo later subject in the curriculum requires it. It sits beside Administrative Law (35/09), which asks how governments are held to the law, and Research Methods in Political Science (35/18), whose tools judge whether a policy worked. What this piece gives youYou will not be able to write a cost-benefit analysis. You will be able to read a news story about a new tax, ban or scheme and ask the five questions a policy analyst asks. Easier first reads: How a Law Gets Made (18/07), How Government Actually Works (18/01) and Where Public Money Goes (18/08). The policy cycle: a useful map that is not the territory Textbooks draw policy as a loop: a problem is noticed, put on the agenda, a solution is designed, a decision is made, the decision is carried out, and the results are evaluated, which sends you back to the start. The idea goes back to Harold Lasswell's 1956 account of the "decision process" in stages, and nearly every introduction to public policy still opens with some version of it. Its value is that it gives you questions to ask at each point. Its weakness is that real policy does not happen in order. Charles Lindblom argued in 1959 that officials do not survey all options and pick the best; they "muddle through", making small changes from where they already are. Solutions often exist before problems: a team has a programme in a drawer and waits for a crisis to attach it to. The cycle is a checklist, not a law of nature. Interactive · The cycle, walked through one real case The case is Ireland's 2002 plastic bag levy. The stages are the textbook ones; the case details are simplified. Sources differ on exact usage figures, so treat "about 90 percent" as the figure reported at the time. Without JavaScript: Ireland's 2002 levy moved from visible litter, to a design choice (a fee at the till rather than a ban), to implementation by shops, to a reported fall of about 90 percent in use, and a later increase of the fee after use crept up. Agenda setting: why some problems get attention and others wait Thousands of real problems exist at any time. Only a few get a minister's, a legislator's or the public's attention. John Kingdon, in Agendas, Alternatives, and Public Policies (1984), described three streams flowing separately. The problem stream: indicators, crises, a disaster on the news. The policy stream: ideas floated by experts and officials, most of which go nowhere. The politics stream: the national mood, elections, lobbying, a change of government. When the three meet, a "policy window" opens, and a policy entrepreneur who has a solution ready can push it through. Windows close again, often within months. A second account, by Frank Baumgartner and Bryan Jones in Agendas and Instability in American Politics (1993), says policy is mostly stable and then changes suddenly, a pattern they call punctuated equilibrium. Attention is scarce, so a problem can be ignored for years and then, when its image changes (from "a medical matter" to "a threat to children", say), move from one committee to a very different one. Interactive · Three streams and a window Problem: how loud is the crisis Policy: how ready is a workable solution Politics: how receptive are decision-makers A metaphor, not a measured model: the threshold of 6 is invented to make the idea playable. Kingdon himself describes the streams as largely independent and the window as partly chance. Play with it. A loud crisis with no ready solution gets hearings and hand-wringing; a ready solution with no crisis waits in a drawer. The practical lesson is Kingdon's: people who want change prepare the policy stream in the quiet years, so that when a window opens they are not drafting from scratch. Instruments: regulation, taxes, spending, information and nudges Once a problem is on the agenda, the government chooses a tool. Political scientists group them roughly as: regulation (a rule, a ban, a standard), taxes and prices (change what a choice costs), spending and subsidies (pay for a service or reward a behaviour), information (warnings, labels, campaigns) and nudges (changing the default or the way choices are shown, without banning anything). Each acts on a different lever, and the same goal can be pursued with any of them. To cut sugar intake, Mexico taxed sugary drinks from January 2014 at one peso per litre; a study in the BMJ estimated purchases fell about 6 percent over 2014 and about 12 percent by December relative to earlier trends. The UK chose a levy on manufacturers' sugary drinks, in force from April 2018, which pushed producers to reformulate. Others rely on labels or school-meal rules. The core economic point about price instruments is that a tax lets each firm or person choose where to cut, and so reaches the same target more cheaply than a uniform rule. Suppose three factories must together cut pollution by a fixed amount, and cutting costs each of them a different amount. A uniform standard makes each cut the same share, including the one for whom it is dearest. A tax makes everyone cut until the last unit costs the same as the tax, so the cheap cutters cut more. Try it. Interactive · Same target, two instruments Total cut required (units) How different the factories' costs are Three factories whose cost of the next unit cut rises in proportion to how much they have already cut: slopes 4/r, 4 and 4r (r is the slider). Costs are in arbitrary money units. Textbook model; real regulators do not know these slopes, which is the standard argument for prices and tradable permits. With r = 1 the factories are identical and the two tools cost the same. As the spread grows, the tax pulls ahead. The caveats matter as much as the result: the model assumes the regulator can set the right tax without knowing costs (it cannot, so it adjusts), and it ignores who pays. A flat tax on fuel hits a poor household harder, which is why many carbon taxes come with rebates. Nudges are the cheapest instrument and the most oversold. A well-known 2003 study by Eric Johnson and Daniel Goldstein found that countries where people must opt out of organ donation reported far higher consent than those where they must opt in. Later work cautions that consent is not donation: hospital systems and family permission matter as much as the default. Implementation: the gap between a law and what happens Jeffrey Pressman and Aaron Wildavsky's 1973 book Implementation (subtitled "How Great Expectations in Washington Are Dashed in Oakland; or, Why It's Amazing That Federal Programs Work at All") followed a federal job-creation scheme in Oakland, California. Their lesson: a programme that needs agreement from many separate offices has many chances to fail. Each "clearance" is a point where someone can delay or veto. If each has a high chance of agreement, the chain still frays, because probabilities multiply. P(success) = p × p × … × p = pnn clearances, each passed with chance p; 0.9 ten times gives about 35 percent Interactive · The clearance chain Chance each office agrees Offices that must agree A simple multiplication that assumes the offices decide independently. Real offices are not independent, and later scholars argued that coordination and bargaining can raise the odds. Pressman and Wildavsky's own point was the warning, not the exact number. A second source of gaps is the person at the counter. Michael Lipsky's Street-Level Bureaucracy (1980) argued that teachers, police officers, caseworkers and nurses make policy in practice: they have more cases than time, so they ration attention and bend rules. Policy on paper is what the capital writes. Policy in practice is what thousands of workers do when the line outside is long. Good designers ask: who has to do this, with what time, and what happens if they simply cannot? Evaluation: what would have happened anyway? The evaluator's central question is about a world nobody saw: what would have happened without the policy? This unseen outcome is the counterfactual. Comparing a group before and after a policy is the obvious test, and it is often badly wrong, because things change on their own: the economy grows, a disease wanes, a school year ends. Mexico's Progresa programme, begun in 1997, gave poor families cash if their children went to school and clinics. Because it could not reach every community at once, the government drew lots for the first wave: of 506 communities in the evaluation, about 320 got the money first and about 186 waited (sources differ by one). Surveys every six months compared the two groups. Enrolment, especially in secondary school, rose in the treated communities. The programme was renamed Oportunidades in 2002 and later Prospera, and cash-transfer schemes with conditions spread to many other countries, Brazil's among them. The 2019 economics Nobel prize, shared by Abhijit Banerjee, Esther Duflo and Michael Kremer, honoured this style of experimental evaluation of anti-poverty policy. Interactive · Before-and-after versus a comparison group True effect of the programme (points of enrolment) What would have happened anyway (trend, points) Invented, illustrative numbers: both groups start at 60 percent enrolment and both are hit by the same background trend. Real estimates carry sampling error, which this toy leaves out. Set the trend to +5 and the effect to 4. A naive before-and-after comparison claims a 9-point success. The comparison group reveals that 5 of those points would have come anyway. Set the trend negative and a working programme looks like a failure. The lesson is the one Progresa's designers acted on: a policy is judged against a counterfactual, and the best counterfactual is a comparison group chosen by chance. The methods piece (Research Methods in Political Science, 35/18) takes this much further. Evidence-based policy, and its limits "Evidence-based policy" means choosing policies because rigorous evaluations found they work. Governments have built institutions for it: in the UK, the What Works Network was launched in 2013 as a set of centres that synthesise evidence for areas such as crime, education and ageing. A cautionary example is "Scared Straight", a programme that takes at-risk teenagers into prisons to frighten them. It was popular and seemed obviously sensible. Systematic reviews of randomised trials found it did not reduce offending and, on average, probably increased it. Evidence overturned common sense. The approach has limits, and its own defenders list them. Published results overstate. Journals prefer significant findings, and small studies that happen to land high are the ones that get published. Stefano DellaVigna and Elizabeth Linos (Econometrica, 2022) compared 126 trials run by two US "nudge units" with 26 academic papers: the academic papers averaged an effect of 8.7 percentage points on take-up, and the units' own trials 1.4 points. Publication bias, they estimated, explains much of the gap. Other researchers disagree on how large the true effect of nudges is: one 2022 meta-analysis found a moderate effect, and a reanalysis argued that after correcting for publication bias there is no clear evidence of any. What worked there may not work here. A result from Kenyan schools or a New Haven neighbourhood tells you about that place; whether it carries to Lagos, Lima or Leeds depends on how the programme works and who delivers it. Angus Deaton and Nancy Cartwright made this argument forcefully in 2018. Even the famous Kenyan school-deworming study (Miguel and Kremer, 2004) has been re-examined and argued over by later researchers, with reviews disagreeing about its size. And what is measured gets gamed. Where a number becomes the target, people optimise the number. Interactive · Why published effects run high True effect (percentage points) People per group in each trial 600 simulated trials of a programme that raises take-up from 10 percent. Only trials that are positive and significant at the usual 5 percent level count as "published". Illustrative simulation with a fixed random seed. With a true effect of 1 point and 400 people per group, the few trials that clear the bar overstate the truth by several times. Make the trials bigger and the exaggeration fades. This is why evaluators ask for pre-registered trials, large samples and replications, and why a single dramatic study is a reason for interest, not a policy. What a graduate just sees The policy cycle is a checklist of questions, not a description of how things happen. Solutions often wait for problems. A problem gets attention when a crisis, a ready solution and a receptive government line up. Prepare in the quiet years. The same goal can be pursued with a rule, a price, a payment, a label or a default. Ask which lever is being pulled and who pays. A price lets people who find cutting cheap do more of it, which usually reaches a target more cheaply than a uniform rule. Probabilities multiply: a plan that needs many separate yeses is far less likely to survive than each yes suggests. Policy is made at the counter as well as the capital. Ask who has to do this, and with what time. "It worked" means "it did better than what would have happened anyway". Ask for the comparison group. Published effects are inflated. One striking study is a lead, not proof; and what worked in one place may not work in another. Where it shows up next Research Methods in Political Science (35/18): the tools for finding a counterfactual, from field experiments to natural experiments. Administrative Law (35/09): the courts' side of implementation, asking when an agency's rule or decision can be challenged. Public Economics (34/49) and Behavioral Economics (34/46): the economics behind taxes, public goods and nudges. In the world: a city councillor deciding between a ban and a fee, a ministry of health asking for a pilot before a national rollout, an NGO choosing which programme to fund. Congestion charges (Singapore began its scheme in 1975, London in 2003) are the same story again: a price chosen, an agenda window, an implementation challenge, an evaluation. If you want to go deeper 📘 Textbook. Thomas Birkland, An Introduction to the Policy Process (Routledge): the standard undergraduate text on the cycle, agenda setting and theories of change. 📘 Textbook. Paul Cairney, Understanding Public Policy (Palgrave): short, critical, and strong on why the cycle is a simplification. 📘 Gentler. Abhijit Banerjee and Esther Duflo, Poor Economics (PublicAffairs, 2011): policy evaluation told through stories from India, Kenya, Mexico and elsewhere. 🌐 Free course. MIT OpenCourseWare 14.73, The Challenge of World Poverty (Banerjee and Duflo, Spring 2011): lectures that apply evaluation to real programmes. The takeaway Policy is a chain: a problem gets attention, a tool is chosen, many people carry it out, and someone asks what would have happened anyway. Each link can break, and each can be examined. Read any new policy by asking which link you are being asked to take on trust. Try this: this week, take one policy in the news, a tax, a ban or a scheme, and write down its goal, its instrument, who has to carry it out, and what comparison would show whether it worked. Sources & Further Reading Sources. Policy cycle: Lasswell, The Decision Process (1956); Lindblom, "The Science of Muddling Through", Public Administration Review (1959). Agendas: Kingdon (1984); Baumgartner and Jones (1993). Ireland's levy: introduced 2002 at 15 cents, a drop of about 90 percent reported by the government at the time (BBC News, 2002 and other reports; per-person figures differ between sources, and critics note bags are reused as bin liners). Mexico's soda tax: Colchero et al., BMJ (2016), about 6 percent fall in 2014 and about 12 percent in December 2014. UK Soft Drinks Industry Levy: announced 2016, in force 6 April 2018. Nudges: Johnson and Goldstein, Science (2003); DellaVigna and Linos, Econometrica 90(1), 2022, 81-116 (1.4 vs 8.7 points; 126 trials vs 26 papers); the Mertens et al. meta-analysis and the Maier et al. correction, PNAS (2022). Implementation: Pressman and Wildavsky (1973); Lipsky (1980). Progresa: renamed Oportunidades 2002; evaluation of 506 communities, about 320 treatment (J-PAL and Attanasio, Meghir and Santiago, Review of Economic Studies); 2019 Nobel to Banerjee, Duflo and Kremer. What Works Network: launched 2013 (UK government). Scared Straight: Cochrane systematic review of randomised trials (Petrosino and colleagues). Deaton and Cartwright, "Understanding and misunderstanding randomized controlled trials", Social Science & Medicine (2018). Miguel and Kremer, Econometrica (2004). Sections on the nudge-unit and trial simulation are the author's own illustrations. This piece describes how policy works; it is not advice on any particular policy. 🌐 MIT OpenCourseWare 14.73 📘 Banerjee & Duflo, Poor Economics 📘 Kingdon, Agendas, Alternatives, and Public Policies