  Philosophical work on secession falls into three main categories: (1) attempts to develop an account of the moral right to secede (understood either as a claim-right or as a mere liberty), (2) investigations of the compatibility or incompatibility of secession with constitutionalism, and (3) attempts to determine what posture international law should adopt concerning secession. In each of these areas of inquiry, as well as in the connections among them, exploration of the moral issues of secession provides a powerful lens through which to examine some of the most important issues of moral-political theory, including perhaps the most fundamental issue of all: what gives a state a valid claim to its territory?