This Element argues that property rights and the territorial rights of states in Kant's legal theory provide a strong justification for the expansion of international law. Central to the argument is Kant's theory of legal obligation, according to which a right to external things is only possible if it can genuinely bind all those on whom it must impose an external duty. Given the global scope of this legal obligation in Kant's account, it can only be achieved through the implementation of a shared international legal order regulated by a principle of reciprocity in external relations. Kant's conception of legal obligation thus requires us to leave the state of nature beyond domestic legal systems towards an international legal order. The author also examines how the international legal order differs from a world state, and how it can be consistent with national legal systems.
