Shawcross was Britain’s Chief Prosecutor at the Nuremberg war crimes trials. He was made a King’s Counsel in 1939 and at the start of the war was appointed Chairman of the Enemy Aliens Tribunal. During the war his most important posts were Deputy Regional Commissioner of the South Eastern Region and Regional Commissioner of the North Western Region. In 1945 Shawcross was made Attorney General in the new Labour government and it was in this capacity that he went to plead the Allied case before the International Military Tribunal in Nuremberg. This Tribunal had been authorized by the US, UK, USSR and provisional French governments in August 1945 although it had been publicly announced from the beginning of the war that war criminals would be tried. Shawcross was at the first and most famous of the trials which began in November 1945 and continued for ten months. There were 22 defendants including political and military leaders, Gestapo, SS and SA, most of whom were found guilty. The Tribunal did not accept Shawcross’s case that the German Army and Navy were themselves criminal organizations.