  Since it competes, rather than build upon, the orthodox view that institutions communicate or tacitly endorse norms (which thereby become legally valid), pure interpretivism has no use for the orthodox notion of norms understood to play substantial explanatory roles (or for a metaphysically important notion of a law, as distinct from the informal notion that picks out statutes or other legislation). It is not a doctrine about the conditions of validity of norms. Legal norms (or other standards) may figure in conclusions of reasoning that summarize the legal effect of institutional practice and are useful for exposition. Since standards so understood are derived from the explanation of the legal effect of practice, their existence is not constitutively responsible for the effect. Standards may also play an epistemic role: we may draw inferences about what rights and obligations exist from tried and tested formulations of standards, but the inferences are always subject to independent confirmation and the formulations are subject to revision (Dworkin 1978: 76; Greenberg 2007; Stavropoulos 2013).