The Principle of Primacy: How the European Court of Justice's Costa v. ENEL Ruling Established EU Law's Supremacy

On July 15, 1964, the European Court of Justice (ECJ) handed down a judgment in Case 6/64 that permanently restructured the sovereignty of European nations. Ruling on a minor dispute over an unpaid electricity bill, the court declared that the law stemming from the European Economic Community (EEC) Treaty constituted an independent legal order that could not be overridden by domestic legislation.[1][3]

The case originated at the end of 1962, when the Italian government nationalized the electricity sector, transferring assets from private companies like Edisonvolta to a new state monopoly, ENEL. Flaminio Costa, a Milanese lawyer and Edisonvolta shareholder, refused to pay his first ENEL bill of 1,925 lire, initiating a legal challenge against the state.[1]

Costa was represented by Gian Galeazzo Stendardi, a lawyer who recognized the nationalization as a vehicle to test the boundaries of European law. Stendardi argued that the Italian nationalization law violated the EEC Treaty, specifically provisions concerning the single market and state monopolies.[1]

The strategy required navigating the Italian legal system. In the initial lawsuit, Justice of the Peace Antonio Carones referred the matter solely to the Italian Constitutional Court (ICC), asking it to evaluate the nationalization law's conformity with both the Italian Constitution and the EEC Treaty.[1]

On February 24, 1964, the ICC delivered a ruling grounded in traditional statutory interpretation: lex posterior derogat legi anteriori, meaning later law repeals earlier law. The ICC concluded that because the 1962 ENEL nationalization law was enacted after Italy's 1957 ratification of the Treaty of Rome, the newer domestic law prevailed.[1]

When Costa received a second electricity bill, he sued again. This time, the case came before Judge Vittorio Emanuele Fabbri, who filed preliminary references to both the ICC and the ECJ under Article 177 of the EEC Treaty, forcing a direct confrontation between the two legal systems.[1]

Before the ECJ, the Italian government argued that Judge Fabbri's reference was "absolutely inadmissible." They maintained that the Italian courts were bound by the ICC's recent ruling and that domestic law must take precedence over the EEC Treaty.[1]

The ECJ, with Robert Lecourt as Judge Rapporteur and Maurice Lagrange as Advocate General, rejected Italy's argument. The court asserted that the preliminary ruling mechanism under Article 177 operates independently of any domestic law, establishing its own jurisdiction over the matter.[1][2]

In its substantive ruling, the ECJ established the doctrine of primacy. The court stated that the EEC Treaty created its own legal system which became an integral part of the legal systems of the member states, requiring national courts to apply it.[1]

The judgment explicitly severed European law from domestic legislative timelines, declaring that "...the law stemming from the treaty, an independent source of law, could not, because of its special and original nature, be overridden by domestic legal provisions, however framed, without being deprived of its character as community law and without the legal basis of the community itself being called into question."[3]

This supremacy was not merely theoretical; it was a functional necessity. The ECJ recognized that if member states could unilaterally adopt safeguard measures or pass subsequent laws to bypass EEC obligations, the common market would collapse into a patchwork of contradictory national regulations.[2]

While the ECJ ultimately found that the specific Treaty provisions Costa cited did not have direct effect—meaning Costa himself could not enforce them against the state to avoid his bill—the establishment of primacy meant that national courts were now obligated to resolve conflicts in favor of European law.[2]

The Costa v. ENEL ruling shifted the ultimate authority on European matters from national constitutional courts to the ECJ. It established that joining the European project required a permanent limitation of sovereign rights, a principle that remains the structural foundation of the modern European Union.[4]