This book focuses on OLAF, the European Unions anti-fraud office, and examines the role of and challenges concerning fundamental rights in OLAFs composite enforcement procedure. The mission of OLAF (Office Europen de Lutte Antifraude) is to fight fraud, corruption and any other illegal activities that affect the financial interests of the European Union. To this end, OLAF carries out administrative investigations, in which it gathers evidence itself, and coordination cases, in which it coordinates the Member States investigations. OLAFs investigation and coordination efforts are conceived of as mere derivatives of other more traditional forms of law enforcement cooperation in which authorities enter into obligations to cooperate with one another, but in which each acts to fulfill these obligations within its own separately identifiable legal order and on the basis of its own law. This system, in its most conventional form, is founded on the notion of territorial sovereignty.If we extend the logic of this approach from enforcement (the sword) to fundamental rights (the shield), issues in relation to the latter and the accompanying responsibility to prevent and/or remedy them can arise only in individual (sovereign) legal orders. The way in which we view OLAF, as an evolved cognate of traditional forms of law enforcement cooperation, therefore directly dictates which fundamental rights issues enter into the equation, and in which manner. This book proposes an innovative way of looking at OLAF, which we refer to as composite enforcement procedures. In this type of procedure, responsibilities for the entirety of enforcement are attributed to inextricably interlinked European Union and Member State legal orders. If we observe OLAF through this new lens, fundamental rights issues that would otherwise go unnoticed come to the forefront. These are issues that arise not in individual legal orders, but rather between or among theEuropean Union and the Member States. This book addresses these fundamental rights challenges and makes concrete recommendations on how they can be addressed and resolved.