This important volume provides an up-to-date overview of the main questions currently discussed in the field of EU criminal law. It makes a stimulating addition to literature in the field, while offering its own distinctive features. It takes a four-part approach: firstly, it addresses issues of a constitutional nature, such as the EU competence in the field of criminal law, the importance of the principle of subsidiarity and the role played by the different EU institutions. Secondly, it looks at issues linked to the quest of the right balance between diversity and unity, and focuses in particular on the special relationship between approximation and mutual recognition. Thirdly, it focuses on the balance between security and freedom, or, in other words, between the shield and sword functions of EU criminal law. Special attention is given here to transatlantic cooperation, data protection, terrorism, the European Arrest Warrant and the European Investigation Order. Finally, it examines the importance of balanced relations between criminal justice actors