This book delves into the complex world of international conventions on terrorism and organized crime, revealing the inherent challenges that arise when member states attempt to align these obligations with their national legal principles. Highlighting the divergence in national laws concerning criminalization and jurisdiction, the book explores the resulting obstacles in state cooperation, including the surrender of fugitives, information exchange, and forfeiture. Despite the proliferation of multilateral conventions, the author argues that effective state cooperation ultimately hinges on bilateral agreements, as national laws often lack the necessary symmetry for reciprocal modalities of cooperation. The book concludes with a compelling call for consistency in the implementation of international conventions at the national level, emphasizing that states will only embrace multilateral treaties as a basis for cooperation if they meet customary requirements and ensure similarity of laws between requesting and requested states. A must-read for scholars, policymakers, and practitioners seeking a deeper understanding of the complexities surrounding state cooperation in combating terrorism and organized crime.