Abstract

Norman Kretzmann's recent analysis of the natural law slogan ``lex iniusta non est lex'' (an unjust law is not a law) demonstrates the coherence of the slogan and makes a case for its practical value, but I shall argue that it also ends up showing that the slogan fails to mark any interesting conceptual or practical division between natural law and legal positivist views about the nature of law. I argue that this is a happy result. The non-est-lex slogan has been used to exaggerate the extent of disagreement about the nature of law and has diverted critics of natural law theory from recognizing that the main disagreement between natural lawyers and legal positivists centres on theories of practical reason and how they affect our understanding of the relationship between law and morality. This extends the debate about the nature of law somewhat beyond the traditional boundaries of philosophy of law, but these boundaries are due in part to the diversion created by debate over the non-est-lex slogan. Recognizing that the non-est-lex slogan fails on its own to mark any interesting practical or conceptual division between natural law theories and legal positivism should therefore focus and encourage debate on matters of genuine substance between these outlooks. The disagreement, however, may turn out to be primarily metaphysical and explanatory and not normative in nature.