Norms conferring public or private powers, i.e., the competence to issue other norms, play a very important rôle in law. But there is no agreement among legal philosophers about the nature of such norms. There are two main groups of theories, those that regard them as a kind of norms of conduct (either commands or permissions) and those that regard them as non-reducible to other types of norms. I try to show that reductionist theories are not quite acceptable; neither the (...) command-variety (Kelsen, Alf Ross inOn Law and Justice), nor the permission-variety (von Wright, Kanger, Lindahl) provide a satisfactory account of competence norms.Among the authors who maintain that competence norms are different from (and hence not reducible to) norms of conduct are Hart, Ross inDirectives and Norms, and Searle. Ross and Searle distinguish between regulative and constitutive rules as two radically different kinds of rules and classify competence norms among constitutive rules. This distinction runs parallel to von Wright's distinction between rules that are prescriptions and determinative rules. While the first regulate actions (by commanding, prohibiting, or permitting them), determinative rules define certain concepts. To view competence norms as (partial) definitions of certain legal concepts (like those of legislator, judge, etc.) seems to open interesting perspectives and to shed light on at least one aspect of these elusive norms. (shrink)