This contribution distinguishes between two forms of rights discourse in the writings and practice of René Cassin. The first position was that of an advocate of humanitarian rights, understood as falling within the laws of war. His work on behalf of disabled WWI veterans was the origin of this commitment. Overlapping with humanitarian rights were human rights, as adumbrated in the Universal Declaration of Human Rights he helped to draft and to persuade the UN to adopt in December 1948. Human rights set down a supranational standard against which all nations had to measure their actions in peacetime as well as in wartime. The problem was that when Cassin dealt with the Jewish population of Palestine, he saw their cause in terms of human rights, the right to form their own state, whereas when he approached the question of Palestinian rights, he framed them in terms of humanitarian rights. The same was true for Muslims in Algeria. He failed to speak out on human rights violations both in Israel and in Algeria during the ongoing Arab–Israeli conflict and during the Algerian War of Independence. His universalism fractured when it came to violent conflicts between Europeans and non-Europeans in decolonization after 1945.