On November 20, 1945, six months after the surrender of Nazi Germany to allied forces, twenty-one military, political, media, and business leaders of the Third Reich filed into the dock of the Palace of Justice in the devastated and occupied German city of Nuremberg. There they stood trial for the most heinous crimes known to humankind, which were committed during World War II. Over the course of the next eleven months, unprecedented trials that profoundly influenced the development of international law and how governments must treat civilian populations unfolded. There were moments of lofty rhetoric and high drama, but often there was also the tedium that has characterized most criminal trials throughout history.

The four major victorious allied powers in the European theater of World War II—the United States, the United Kingdom, France, and the Soviet Union—met in London during the summer of 1945. On August 8 these nations...