Henri Donnedieu de Vabres is a fascinating but cryptic figure within the circles associated with international criminal justice in the interwar period. One of the most active participants in the 1920s ebullience around international criminal law as President of the AIDP and member of the ILA, he eventually became the French judge at Nuremberg as well as a member of the ILC and the drafting committee for the genocide convention. For all that model trajectory, Donnedieu de Vabres had a unique and somewhat iconoclastic view of the fundamental purpose of international criminal justice. His first intellectual love was for private international law and throughout his career he saw international criminal law as fundamentally a conflict of laws issue, as a result of the worldwide movement of criminals. His view of an international criminal court was very much aligned with the AIDP’s early suggestion that it should be a criminal chamber of the PCIJ to adjudicate disputes between states over the exercise of criminal jurisdiction. He was an odd fit for the Nuremberg tribunal, where he was mostly silent but took a strong and surprising line during deliberations. He remains a neglected but pivotal figure in the early development of international criminal justice.