European Union Law: The Deepest Legal Union, and Its Rivals

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.

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.

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.

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.

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.

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.

Bloc	Founding	Court	How far it goes
Mercosur (Argentina, Brazil, Paraguay, Uruguay, Bolivia since 2024; Venezuela suspended since 2016)	Treaty of Asunción, 26 March 1991	Permanent 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 2006	Andean 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 1993	Community Court of Justice, Abuja	Since 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 Union	Constitutive Act, Lomé 2000; launched Durban 2002 (replacing the OAU of 1963)	The planned Court of Justice never became operational; the African Court sits at Arusha	Unusual 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.