In the debate surrounding the present state of British prisons much has been made of the notion of prisoners’ rights: the claim to a right can be a powerful political device. However, if the debate is to penetrate beyond rhetoric it is essential to examine more closely the nature of and justification for any claim to the existence of prisoners’ rights. An individual asserts a right when she makes a claim to performance, either action or forbearance, on the part of another (Corbin 1919; Hohfeld 1919). The right is legal when the correlative duty is owed at law and moral when the duty is morally enforceable. This chapter will be based on the assumption that a core of basic or moral rights exists and that it should be reflected in law (Gerwith 1984; Pennock and Chapman, 1981).