Abstract

According to the standard positivist picture of law, each legal system contains a master rule that specifies criteria of legality for primary rules.1 A central debate in legal philosophy during the past twenty-five years has concerned the content of the master rule. Exclusive positivists insist that the master rule can only make reference to social facts or sources: “pedigree” criteria.2 As Ronald Dworkin emphasizes, however, some rulings can’t be justified exclusively by reference to pedigreed legal norms.3 Judges sometimes exercise.