Book excerpt: EU criminal justice is a fast developing and challenging area of EU law and policy that requires scholars from different disciplines to join forces. This book is a first attempt to establish such synergies. Coming from different angles, the authors deal with questions in the area of EU substantive criminal law, such as when criminalisation of conduct is an appropriate choice; how the process of (de)criminalisation could be advanced; what the role of evidence could be in this regard; and what consequences criminalisation decisions at EU level have for national legal orders. The book concludes with a demonstration of how similar issues arise in the field of procedural criminal law.