This groundbreaking study seeks to clarify the concept of universal crimes in international law. It provides a new framework for understanding important features of this complex field of law concerned with the most serious crimes. Central issues include the following: What are the relevant crimes that may give rise to direct criminal liability under international law? Are they currently limited to certain core international crimes? Why should certain crimes be included whereas other serious offences should not? Should specific legal bases be considered more compelling than others for selection of crimes? Terje Einarsen (1960) is a judge at the Gulating High Court. He holds a Ph.D. (Doctor Juris) from the University of Bergen and a masters degree (LL.M.) from Harvard Law School.