6/64 Falminio Costa v ENEL [1964] ECR 585
EUROPEAN UNION – DOCTRINE OF SUPREMACY – CONFLICT OF LAWS – EEC TREATY AND ITALIAN MUNICIPAL LAW
Facts
In 1962 the Italian Republic introduced a law which nationalised the production and *427 distribution of electricity and created an organisation, ENEL, to which was transferred the property of the electricity undertakings.
The applicant was a shareholder of a firm which had been affected by the nationalisation, and claimed that he was not liable for a bill sent to him for electricity supplied to him by ENEL. In proceedings before the Giudice Conciliatore (Justice of the Peace) of Milan, C claimed that the Nationalisation Law of 6 December 1962 was contrary both to the Italian Constitution and to a number of provisions of the E.E.C. Treaty.
Issues
The European Court of Justice were required to adjudicate upon the doctrine of supremacy as it pertained to the relationship between domestic and Community law, namely whether Community law and the provisions of the various treaties limited the ability of Member States to enact legislation which ran contrary to those provisions.
Decision/Outcome
An Italian law, enacted to bring into effect an international treaty, is no different from any other law, and is subject to the normal rules with respect to implied repeal when it conflicts with other laws. The violation of a treaty provision does not invalidate a domestic law. However, as the Treaty of Rome involved the partial transfer of sovereignty from Member States to the Community itself, a subsequent unilateral law which is incompatible with the aims of the Community could not prevail.
Updated 19 March 2026
This case summary accurately describes the facts, issues, and outcome of Costa v ENEL (Case 6/64), a foundational Court of Justice of the European Union authority establishing the doctrine of EU law supremacy over conflicting national law.
UK readers should be aware of one significant contextual development: following Brexit and the European Union (Withdrawal) Act 2018 (as amended by the European Union (Withdrawal Agreement) Act 2020), the United Kingdom is no longer a Member State of the European Union. The doctrine of EU law supremacy no longer applies as a general principle in the UK domestic legal order. Section 5(1) of the 2018 Act removed the supremacy of EU law, save for limited retained EU law purposes under the transitional framework. Costa v ENEL therefore remains academically and historically important for understanding EU constitutional law and the development of the EU legal order, but it no longer has direct practical application in the UK context. Students studying EU law as a distinct subject, or comparative constitutional law, will still encounter this case as essential reading.
