How a court in Luxembourg established that European law overrides the laws of nations, and why national parliaments accepted it.

There is a court in Luxembourg whose rulings override the laws passed by the elected parliaments of twenty-seven nations. When this court interprets European law, its interpretation binds every member state, every national court, and every national government. A law passed by the German Bundestag, the French National Assembly, or the Italian Parliament can be set aside if it conflicts with European law as the court interprets it. And the nations of Europe have, for the most part, accepted this.

This is one of the most remarkable facts about the European Union, and one of the least understood by outside observers. The European Court of Justice has constructed, through its own jurisprudence, a legal order in which European law is supreme over national law - a claim of authority that no treaty explicitly granted in the sweeping form the court eventually asserted, and that the court established largely through the accumulating weight of its own decisions.

How a court achieved this, why national governments and national courts went along with it, and what it means for the nature of European power is a story that explains a great deal about how the European Union actually works - and about a kind of authority that has no real American equivalent.

The European Court of Justice, based in Luxembourg, is the supreme judicial authority of the European Union. Its formal function is to ensure that European law is interpreted and applied uniformly across all member states, and to resolve disputes about the meaning and validity of European law.

The court hears several kinds of cases. It rules on actions brought by the Commission against member states that fail to comply with European law. It hears disputes between European institutions. It reviews the legality of acts of the European institutions. And, most consequentially, it answers questions referred to it by national courts about the interpretation of European law - the mechanism through which it reaches into the legal systems of every member state.

This last function - the preliminary reference procedure - is the key to the court’s power. When a national court hears a case that turns on a question of European law, it can, and sometimes must, refer the question to the European Court of Justice for a definitive ruling. The European court answers the question of European law; the national court then applies that answer to decide the case. Through this mechanism, the European court’s interpretation of European law penetrates directly into national legal proceedings throughout the Union.

The court’s supremacy rests on two doctrines that it established early in the history of European integration and that are not stated in this form in the founding treaties. The court derived them through interpretation, and they became the constitutional foundation of the entire European legal order.

The first is direct effect. In a landmark ruling in the early 1960s, the court held that provisions of European law can create rights for individuals that national courts must protect - that European law is not merely an agreement between states but a body of law that individuals can invoke directly in their national courts. This transformed European law from a matter of inter-state obligation into a source of directly enforceable individual rights.

The second is supremacy, or primacy. Shortly afterward, in another foundational ruling, the court held that European law takes precedence over conflicting national law - that where national law and European law conflict, European law prevails, and national courts must set aside the conflicting national provision. This doctrine, too, was not spelled out in the treaties in the absolute form the court asserted. The court reasoned that the entire project of European integration would be impossible if member states could override European law through their own subsequent legislation, and it concluded that supremacy was a necessary implication of the system the treaties had created.

Together, direct effect and supremacy constructed a legal order unlike any other international arrangement. European law became a body of directly enforceable law that overrides national law and reaches individuals through their own national courts - a quasi-constitutional order built by judicial interpretation.

The most puzzling aspect of this story is why sovereign nations, with their own elected parliaments and their own proud legal traditions, accepted a doctrine that subordinates their laws to the rulings of a supranational court.

Part of the answer is that acceptance came gradually and through national courts rather than through dramatic political decisions. The European court’s doctrines were absorbed into national legal systems case by case, as national courts referred questions, received answers, and applied them. There was rarely a single moment of political confrontation in which a national parliament was asked to surrender its supremacy. The order was built incrementally, through legal practice, in a way that did not force a political crisis.

Part of the answer is that the doctrine served interests that national governments valued. A uniform, enforceable European legal order is what makes the single market function - businesses can rely on European rules being applied consistently everywhere, which is precisely the predictability that makes cross-border commerce possible. The supremacy of European law is the price of the single market’s reliability, and governments that wanted the single market accepted the legal order that underpinned it.

And part of the answer is that the acceptance has never been quite complete or unconditional. Several national constitutional courts - the German court most prominently - have asserted that their acceptance of European law’s supremacy has limits, that they retain ultimate authority to determine whether European acts exceed the powers the member states conferred. The relationship between the European court and the national constitutional courts contains a permanent, usually dormant, tension about who has the final word.

The European Court of Justice - Key Facts

Location: Luxembourg
Function: supreme interpretation and application of EU law
Key mechanism: preliminary references from national courts
Foundational doctrines: direct effect and supremacy of EU law
Source of doctrines: judicial interpretation, not explicit treaty text
Effect: EU law overrides conflicting national law
Unresolved tension: national constitutional courts assert ultimate limits

What distinguishes the European Court of Justice’s power is its quietness. The court does not command armies or control budgets. It issues judgments - technical, reasoned, often concerned with apparently dry questions of regulatory interpretation. And yet those judgments have reshaped the legal order of an entire continent.

The court’s most consequential rulings have often concerned matters that sounded technical - the free movement of goods, the recognition of professional qualifications, the application of competition rules, the protection of personal data. But in deciding these technical questions, the court has repeatedly expanded the reach and the force of European law, building the legal architecture of integration ruling by ruling.

This is power exercised through reasoning rather than through force or money - the characteristically European mode. The court persuades, interprets, and accumulates authority through the consistency and the logic of its judgments, and through the willingness of national courts to follow them. It is a kind of power that operates almost entirely outside the awareness of the public, and that has nonetheless been one of the most powerful engines of European integration.

American observers, accustomed to the United States Supreme Court, tend to assume a rough equivalence between the two institutions. There are real similarities - both are supreme courts that can strike down laws and that shape the constitutional order through interpretation. But the differences are profound.

The United States is a single nation with a single constitution that its Supreme Court interprets. The European Union is a union of nations, and the European Court of Justice asserts the supremacy of European law over the laws of nations that retain their own sovereignty, their own constitutions, and their own constitutional courts. The European court’s authority is more contested, more dependent on the continuing acceptance of national courts, and more carefully bounded than that of the American Supreme Court.

The second misunderstanding is to underestimate how much of European integration has been driven by the court rather than by political decision. Many of the most important steps in building the European legal and economic order were taken not by treaties or by legislation but by the court’s interpretation of what the existing arrangements required. The court has been, throughout the history of European integration, one of its principal architects - and arguably the one least visible to outside observers.

For companies and investors, the practical implication is that European law is shaped continuously by judicial interpretation, and the direction of that interpretation matters. A ruling of the European Court of Justice can change the legal landscape for an entire industry - reshaping the rules on data, competition, taxation, or market access - with consequences as significant as any legislation. Watching the court is not a specialist legal preoccupation; it is a strategic necessity for anyone whose business depends on the rules of the European market.

The European Court of Justice built the supremacy of European law over the laws of nations not through force or treaty but through the patient accumulation of its own reasoned judgments - the purest example of how Europe exercises power through institutions rather than through might.

Friday’s EuroTasteDaily Review brings the court’s abstract authority down to earth, tracing how a handful of landmark rulings - about a blackcurrant liqueur, a customs dispute, the right to be forgotten - reshaped European life in ways that touch ordinary people and ordinary businesses every day. And this weekend’s Power Figures supplement profiles Roberta Metsola, the President of the European Parliament.