This chapter shows how government constrains ownership in pursuing its objectives, considers the police power and eminent domain as alternative ways of achieving them in light of the dispute between Locke and Bentham, and introduces a central concept of the book, involuntary exchange. Exercising its police power, government may destroy the value of property without compensation, but eminent domain takings require that owners be paid full compensation for their loss. Eminent domain thus governs involuntary exchanges, compelled sales of property to government at a price equal to the replacement value of the property taken, and constitutes an organizational midpoint between markets and liability as institutions to govern exchange. The Supreme Court’s problematic attempts to distinguish between the two powers, and determine when a taking has been for public use, are considered, and two modern scholarly attempts to address the takings question, one Benthamite and one Lockean, are compared.