This course traces the co-evolution of empire and international law from the 19th to the 20th century, analyzing how imperial structures shaped legal conceptions of international personhood, sovereignty, and national belonging. Beginning with the 19th century, we analyze the expansion and consolidation of European colonial empires and the emergence of a global legal hierarchy rooted in the standard of civilization and doctrines such as extraterritoriality and unequal treaties. Next, we turn to the interwar period, exploring how the rise of self-determination, the emergence of new legal persons, and the creation of the League of Nations and International Court of Justice sparked both conceptual innovations and efforts to codify international law. Finally, we move to the post-war period to investigate the legal foundations of the ‘liberal international order’, including the UN Charter, the Bretton Woods system, and the codification of human rights. We assess how international law facilitated both imperial adaptations and anti-imperial challenges, culminating in a discussion of formal decolonization and the emergence of Third World Approaches to international Law (TWAIL).