This Article argues that ownership is a form of authority that is constitutionally basic in liberal societies. At the same time, I argue, neither the particular benefits nor burdens that accede to the position of ownership are. By distinguishing between a principle of sovereignty, which I argue constitutes the core authority of owners, and a principle of accession, which I argue regulates the distribution of benefits (and burdens) attached to the position, we can see how this is so. Taxation, regulation, expropriation, by means of which benefits are withheld or burdens imposed, are not then attacks on property that undermine the position of ownership itself. Attacks on the office of ownership as such would be, rather, acts by the state that deny the basic sovereign authority of owners to set the agenda that regulates private activity with respect to a thing, e.g., by subordinating owners to the private choices of others.