Primacy of European Union law

The primacy of European Union law (sometimes referred to as supremacy) is an EU law principle that when there is conflict between European law and the law of Member States, European law prevails; the norms of national law have to be set aside. This principle was developed by the European Court of Justice, and, as interpreted by that court, it means that any norms of European law always take precedence over any norms of national law, including the constitutions of member states. Although national courts generally accept the principle in practice, most of them disagree with this extreme interpretation and reserve the right, in principle, to review the constitutionality of European law under national constitutional law.

In Costa v. ENEL. Mr Costa was an Italian citizen opposed to the nationalising of energy companies. Because he had shares in a private corporation subsumed by the nationalised company, ENEL, he refused to pay his electricity bill in protest. In the subsequent suit brought to Italian courts by ENEL, he argued that nationalisation infringed EC law on the State distorting the market. The Italian government believed that this was not even an issue that could be complained about by a private individual, since it was a national law decision to make. The European Court of Justice ruled in favour of the government, because the relevant Treaty rule on an undistorted market was one on which the Commission alone could challenge the Italian government. As an individual, Mr Costa had no standing to challenge the decision, because that Treaty provision had no direct effect. But on the logically prior issue of Mr Costa's ability to raise a point of EC law against a national government in legal proceeding before the courts in that member state the ECJ disagreed with the Italian government. It ruled that EC law would not be effective if Mr Costa could not challenge national law on the basis of its alleged incompatibility with EC law.

It follows from all these observations 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.

In other cases, countries write the precedence of Union law into their constitutions. For example, the Constitution of Ireland contains a clause that, '"No provision of this Constitution invalidates laws enacted, acts done or measures adopted by the State which are necessitated by the obligations of membership of the European Union or of the Communities...."

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