Europe and the law
Europe and the law

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Europe and the law

6.2 The supremacy of EU law

Whenever there is a conflict between the provisions of EU law and the provisions of the domestic (national) law of a member state, then EU law will prevail. This is a principle which was developed by the ECJ as the relationship between domestic and EU law is not clarified by treaty provisions. This is an important principle, as it ensures the proper functioning of the EU. If an EU member state had the power to annul EU law by adopting new domestic (national) law which was in conflict with the EU primary or secondary legislation, or the member states could simply give precedence to domestic (national) law, then the policies set out by the EU would be impossible to pursue and achieve. The principle of supremacy was crystallised in ECJ case law in several progressive stages. With each stage, the supremacy of EU law was enlarged and deepened.

Activity 5 The EU and domestic law

0 hours 25 minutes

In this activity you need to reflect upon a series of situations and decide in which of them the EU law should prevail over the domestic (national) law of an EU member state.

Which law will prevail where there is:

  1. A conflict between EU law and domestic law which pre-dates the EU law?

  2. A conflict between EU law and domestic law which post-dates the EU law?

  3. A conflict between the EU law and national constitutional provisions?



  • 1 The EU law will prevail.

  • A similar situation of conflict between provisions in the EU law and domestic law could be seen in the first case in which the ECJ affirmed the supremacy of European law: Van Gend en Loos v Nederlandse Administratie der Belastingen (Case 26/62) [1963] ECR1. In this case, Van Gend en Loos had imported ureaformaldehyde from Germany into the Netherlands and had been charged duty. This violated the principle of free movement of goods between member states, and more precisely violated Article 25 EC which stated that ‘Custom duties on imports and exports and charges having equivalent effect shall be prohibited between Member States …’

  • Van Gend en Loos claimed reimbursement of the sum before the Dutch courts. The Dutch court referred the issue to the ECJ which, among other things, stated that, by becoming members of the EU, the member states have limited their sovereign rights. One of these rights would be to have the domestic law as supreme law in all matters affecting a sovereign country.

  • 2 The EU law will prevail.

  • This situation was reflected in the ECJ case law in Costa v ENEL (Case 6/64) [1964] ECR 585, which constituted a second step on the ECJ route to defining the principle of supremacy of the EU law. The question asked in Costa was whether a provision of the Italian domestic law, passed after Italy had signed the Treaty of Rome, could take precedence over the conflicting EU law. The ECJ decision, however, was that, although the Italian domestic law had been adopted later and therefore it could be said that it expressed the latest supreme legislative will of the Italian sovereign state, the supremacy belonged to the Community law. According to the ECJ, this is so because with the adherence to the EU, there has been a transfer of power from the member states to the EU institutions and the member states have committed themselves to observe the EU law.

  • 3 The EU law will prevail.

  • One might think that the constitutional provisions of a sovereign state should always prevail over any other source of law. In fact, constitutions are often referred to as the ‘supreme law of the land’, expressing in this way the importance of the rules and principles incorporated in such a legal document. In spite of this, in Internationale Handelsgesellschaft mbH v Einfuhr - und Vorratsstelle fur Getreide und Futtermittel (Case 11/70) [1970] ECR 1125, which had at its core a conflict between EU law and the German Basic Law (the German constitution), the ECJ stated that the EU law must take precedence over any conflicting domestic law regardless of the nature of that law.

Table 4 Summary of rulings

Year Case Ruling
1963 Van Gend en Loos Where there is a conflict between national law and EU law, EU law should prevail
1964 Costa Earlier EU law prevails where there is a conflict between EU law and later national law
1970 Internationale Handelsgesellschaft EU law prevails where there is a conflict between EU law and national law even if the conflict is with a member state's constitution

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