Chapter 1 presents the legal problem central to this book: "creeping competences". After describing the present division of competences between European Union and Member States, it focuses on implied powers as an emblematic case of this phenomenon. Subsequently, it turns to the ECJ and, in particular, to its broadly formulated mandate to clarify the special role this institution plays in the debate on the powers of the EU. Then, the argument show that the issue of legal competence in EU law is ultimately connected with the problem of the authority of the Union. In this authority problem, a material and an institutional dimension are distinguished. These come together in the infamous Maastricht decision of the German Federal Constitutional Court. This decision demonstrates that the questions regarding competences and authority in the European Union ask for an inquiry into the very foundations of the concept of legal power itself.