This chapter discusses the principles of customary international law related to expropriation. It includes an overview of the historical development of the international law of expropriation, as developed in international arbitration decisions, commentators, treaties, and State practice. It also discusses the current state of the customary international law of expropriations, including the various substantive protections established in customary and conventional international law, such as the full compensation standard for expropriation, the public purpose requirement, and the prohibition against discrimination. The chapter concludes that a State may expropriate the property of aliens within its borders, but must compensate the foreigner for full value of the property taken. The primary change in the international law of expropriation since the nineteenth century is that the State may no longer use force against another State to rectify or prevent a taking of property by the host State.
