In recent years, much has been written about the interaction between international law and the political. Yet, the field of International Relations has paid limited attention to how centering the interpretation of the ‘international’ on each of these favors radically different orders. With this book, Leon Sosnowski effectively demonstrates the plausibility of a foreign policy recognizing the primacy of International Law. He does so by synthesizing Hans Kelsen’s legal cosmopolitanism and elements of Hans J. Morgenthau’s classical realism into a new theoretical framework – Normative Effectivism. He argues that it is an international political theory to challenge the current sovereigntist wave, contributing to a sustainable international order. He illustrates his arguments with a novel reading of Kelsen and Morgenthau’s opposition to Carl Schmitt’s worldview. His analysis shows that the post-WWII international system is at a critical crossroads, evidenced by Russia’s post-Cold War