At the end of World War II the Allies faced a threefold challenge: how to punish perpetrators of appalling crimes for which the categories of 'genocide' and 'crimes against humanity' had to be coined; how to explain that these had been committed by Germany, of all nations; and how to reform Germans. The Allied answer to this conundrum was the application of historical reasoning to legal procedure. In the thirteen Nuremberg trials held between 1945 and 1949, and in corresponding cases elsewhere, a concerted effort was made to punish key perpetrators while at the same time providing a complex...