International criminal justice has emerged as a central tenet of the United Nations (UN) system in the post–World War II era. The decision by Allied Forces to prosecute senior political and industrial leaders of Nazi Germany ushered in a new era of international law.3 As Crawford aptly argued, ‘It is not too much of an exaggeration to say that the United Nations era began with a trial and a promise.’4 The trial was the Nuremberg Tribunal, and the promise was that the principles underpinning the Nuremberg Charter were treated as international law.5,6 By introducing a new body of international criminal law, the Nuremberg Charter ‘reached deep’ into traditional notions of State sovereignty, including the laws that governed immunity.