The European Court of Justice has long emphasized the existence of a mutual duty of loyalty between the Community institutions and the Member States. While Article 10 TEC determines the duty of loyalty of the Member States, this thesis examines the legal nature and scope of such duties of the Community institutions. First, through an analysis of the case law of the Court of Justice on the duty of loyalty, the legal figure is outlined. It is then assigned to a Community source of law.

In contrast to previous approaches, the work establishes the duty of loyalty solely on the basis of the Community legal order. Finally, the framework of possible duties of the institutions is defined. The consideration of the relationship between member states and the community is highly topical due to the upcoming constitutional reform of the EU.

The work represents a valuable contribution for all actors involved in the process of constitutional development in the European Convention or in other ways.

The author academically accompanied the preparation of the report on the “Future of the European Union” in the European Parliament. Since then, the author has been engaged in EU promotion in a bank.