Öz This article intends to analyze the relationship and interaction of EC/EU law with the national constitutions of the old and new member states in the light of the legal and constitutional issues and questions such as whether the constitutions of member states allow the delegation or transfer of legislative powers to international organizations with or without limits, what is the legal situation in case of a conflict of the constitutions with the Treaty primary law or community secondary law, and a conflict of a prior or later national law with the Treaty on EU?, do the consitutional courts in member states accept the primacy of EU law obligations and do the courts accept a different attitude for primary or secondary community law and on which principles they base their reasoning? It also focuses on the question of the primacy of EU law and effects of it on the constitutional framework in relation to the national parliaments, federated units, regions and decentralised bodies. Finally, it gives special attention to the relationship of EU law with the fundamental rights and freedoms and its impact on the national constitutions and legal order of member states.