The book provides a thorough analysis of the protection of fundamental rights (right to privacy, legal professional privilege, privilege against self- incrimination, right to an effective remedy and ne bis in idem) in the composite procedures that take place in the context of the Single Supervisory Mechanism (SSM).Within the SSM, the EU and national levels are in constant interaction. The interlocking of EU and national legal orders for the enforcement of EU law challenge traditional systems of control that were designed for and developed in the context of a single State jurisdiction. This book looks into the system of fundamental rights protection, as a mechanism that guides and controls executive action.By studying the mutual interactions of three legal orders (EU, the Netherlands, Greece), the book concludes that in certain instances there are gaps in complete fundamental rights protection.Concrete recommendations are thus brought forward,which are addressed to the ECB, the EU and national courts and the EU legislature and which aim at bolstering the protection of fundamental rights at the intersection between different legal orders and at the interface between administrative and criminal law enforcement.