Devolved bodies are local and regional authorities in the Member States mainly responsible for economic development, environment, transport... In these fields, EU law has progressively become preponderant. How do the devolved bodies implement the European Law? What are the legal consequences and their responsibilities? Firstly, I take a special interest in the foundations of the norms of devolution in Great Britain, federalism in Germany and décentralisation in France. All entities qualified as 'devolved entities' have a power to make subordinate legislation in these matters. It is necessary to note that EC law is uninterested in the form of the national measures applying EC law. It is more a question of degree of decentralization of the state. Secondly, the problem raised results from the legally binding legislation taken on the basis of the EC Treaty. Regulations, directives which are 'sufficiently clear, precise and unconditional' and decisions are directly applicable in national orders. The possibility of confrontation with a national norm, general as individual, is problematic. The Simmenthal jurisprudence implies the national norm should be put aside, even when valid. European law has no competence to regulate the territorial organization of Member States. The principle of institutional autonomy drawn by the ECJ prohibits any interference of the European norm. European institutions are thus limited to the material competences. Consequently, the European norm directly applicable lacks an important element of a normal norm, which is the determination of the organ. That means that this norm cannot be effective without the national norm which is exclusively competent for this determination. Finally, I raise two important problems. On the one hand, the complexity of European law shows the failure to adapt to the coordination between the devolved administration, the national representation and the EU. On the other hand, I underline the lack of direct constraint towards devolved entities which apply European law insofar as the state assumes this responsibility for them. That explains, in part, why the British and French states tend to keep the control of the implementation of European law. The German Länder stand out from this tendency according to general powers enshrined in the Grundgesetz.