ABSTRACT
The first and main prerequisite for international criminal justice is the existence of a body of international criminal law. Nullum crimen, nulla poena, sine praevia lege poenali, the principle that no crime can exist, and no punishment is lawful without a previous penal law, prevents prosecution based on ex post facto norms. After the Second World War, an important precedent for later mechanisms to prosecute human rights violations was set by the Nuremberg and Tokyo trials. The Holocaust and other atrocities committed by the Nazi regime called for the punishment of its military and civilian leaders. The horrors of the Second World War also led to the establishment of the UN itself. The UN Charter was signed on 26 June 1945 in San Francisco, reflecting a determination, among other things, to 'reaffirm faith in fundamental human rights' and 'establish conditions under which justice and respect for the obligations arising from treaties and other sources of international law can be maintained'.
