This book aims to give readers an insight into two dynamics that influence the phenomenon of autonomous public bodies (APBs) in the European legal sphere today. Stephanie De Somer first studies both phenomena-EU impulse and national restraint-as standalone trends and then addresses the tensions between them. The first trend covers EU legislation that obliges Member States to entrust the implementation of substantive supranational rules to entities that enjoy a considerable degree of autonomy vis-a-vis central government institutions. The second trend refers to a counter-movement at the national level, where initiatives have been taken to rationalize and restrain the use of APBs. Central to the book is the somewhat controversial question of whether the EU, which is itself often criticized for lacking democratic legitimacy, is disregarding fundamental principles regarding the democratic legitimacy of national administrations when imposing these institutional obligations on its Member States. As far as domestic law is concerned, the book offers an integrated approach that truly compares national legal systems. De Somer also incorporates the results of in-depth interviews with representatives of APBs in different Member States. Focusing on these two contemporary trends, this book demonstrates the extent to which two fundamental systems of rules and principles increasingly influence and transform the phenomenon of APBs This book is relevant not only for legal academia, but also for scholars working in the fields of political science and public administration. National legislatures, governments, regulatory bodies, data protection authorities and other APBs may also find this book useful.