The inter-war period of European and global history (1919–1939) fascinates by virtue of its uniqueness, the intensity of its developments, and the strategies of crisis managements it has witnessed within the League of Nations framework and beyond. The uniqueness of this period was mainly due to the fact that the identity and interests of major powers were split to a greater extent than held in common. In this time of major strategic and ideological divisions the uniform and consistent operation of positive international law as a major instrument for the preservation of peace was obviously challenged. The legal and political discourse of four major scholars of international law – Scelle, Schmitt, Kelsen and Lauterpacht – had to analytically tackle this challenge to the very viability of international law, the essence of its normativity, and its ability to make the difference in international affairs. As this contribution demonstrates, the complexity of this issue was not always given the similarly required complex attention, and grave implications followed both in legal and political terms. Viability of law in times of division is what requires that continuous attention is paid to the inter-war jurisprudential debate. The issues the four inter-war authors have focused upon retain their major significance in terms of the viability of international law in the post-Cold War international system. Three modern case-studies consequently illustrate the continuing relevance of the inter-war debate.