 The constitutive role of social pressure is sometimes considered an Austinian blemish on Hart’s theory, but there are in any case more serious problems with it as a general account of obligations (Dworkin 1978: 50–54; Raz 1975 [1990: 53–58]). People readily speak of obligations when they are well aware that there are no relevant social practices, as might a lone vegetarian in a meat eating society. And Hart’s practice conditions may be satisfied in cases where there is no obligation but only generally applicable reasons, as when victims are regularly urged to yield their wallets to a mugger. At best, Hart’s theory will apply only to a special class of obligations in which the existence of a conventional practice is an essential part of the reasons for conformity, though even here, the theory is open to doubt (see Dworkin 1978: 54–58; Green 1988: 88–121; cf. Marmor 2011: ch. 3). More recently, some have objected that Hart’s attempt to reduce social rules to social practices fails because rules and practices belong to different metaphysical categories. If so, grounding one in the other is a category mistake. Instead, we should think of the rules of our legal system as grounded in the planning activities of various officials whose intent is to regulate the behaviour of individuals (as well as other bodies) operating within the legal system (Shapiro 2011).