The work addresses the international criminal prosecution of individuals by international courts. It traces the long development of this young area of law since the beginning of the 20th century and spans from the Nuremberg Trials through the UN tribunals to the hybrid courts in Sierra Leone and Cambodia. Particular attention is given to the legal legitimacy and design of the courts. The focus is on the activities and functioning of the International Criminal Court (ICC), which has been in existence since 2002, against the backdrop of its operational start. Here, the proximity to the United Nations plays an important role. Additionally, current issues in the work of the courts and questions regarding the elements of crimes are highlighted.