With the establishment of numerous international and mixed tribunals in recent years, international criminal law has gained unprecedented importance and continues to expand tremendously. This systematic analysis of substantive international criminal law examines its general principles, sources and evolution as well as specific international crimes, providing an in-depth analysis of the Rome Statute of the International Criminal Court (ICC) and customary international law. The updated second edition takes account of the emerging case law of the ICC and other international and national courts in the field. It includes more recent methods of enforcing international criminal law, such as hybrid tribunals, and contains a new separate chapter on implementation.