Soon after World War I, the 1923 Treaty of Lausanne burries the Armenian question. Nevertheless, the 1915 Allied Declaration, the 1919 Paris Peace Conference's work and the 1920 Treaty of Sèvres are key documents for a better understanding of the emergence of international criminal law. In particular, they constitute a legal basis for major innovations such us: the conceptualization of “crime against humanity”; the recognition of the principle of individual criminal responsibility of leaders; and the attempt to materialize the idea of an international judicial intervention in internal State affairs for the defense of the fundamental rights of human beings.