The legal doctrine of supremacy of EU law means that EU labour law takes precedence over domestic labour law. The creation of a new legal order of EU law and its supremacy means that EU institutions may create rules affecting employment and industrial relations, even where some Member States oppose such rules and vote against them in those EU institutions, provided that a voting procedure based on a majority rule applies to that specific field. Where adopted, these rules must be enforced in national courts, even where this involves overriding rules produced by domestic law-making institutions. In the course of time, national constitutional courts have accepted the principles of supremacy of the EU law affirmed by the European Court of Justice, but at the same time they have envisaged a limit to it in the fundamental principles of each national constitution.
This supremacy is well known in certain areas such as sex discrimination, where the domestic law of many Member States has been shaped, and, in cases of conflict, has been repeatedly overridden, by the rulings of the European Court of Justice. Probably the best known example of the impact of these rulings in labour law is G. Defrenne v. Sabena, Case 43/75, (1976) ECR 455, where the European Court decided that, ‘The principle that women and men should receive equal pay, which is laid down by Article 119 EC [now Article 157 TFEU], may be relied on before the national courts. These courts have a duty to ensure the protection of the rights, which that provision vests in individuals, in particular in the case of those forms of discrimination which have their origin in legislative provisions….’
The wider the range of EU competences in the field of employment and industrial relations, the more the EU law they create will come to replace increasingly wide areas of national labour law. An example is the decision of the European Court in Commission v. United Kingdom, Case C-382/92 and Case