Beginning in late 1945, the United States, Britain, China, Australia, France, the Netherlands, and later the Philippines, the Soviet Union, and the People's Republic of China convened national courts to prosecute Japanese military personnel for war crimes. The defendants included ethnic Koreans and Taiwanese who had served with the armed forces as Japanese subjects. In Tokyo, the International Military Tribunal for the Far East tried Japanese leaders. While the fairness of these trials has been a focus for decades, Japanese War Criminals instead argues that the most important issues arose outside the courtroom. What was the legal basis for identifying and detaining subjects, determining who should be prosecuted, collecting evidence, and granting clemency after conviction? The answers to these questions helped set the norms for transitional justice in the postwar era and today contribute to strategies for addressing problematic areas of international law.