1. Introduction

In this chapter, we will try to grapple with one of the most controversial ques­tions in contemporary legal theory: the question about the nature of the norms that confer normative powers or, in a terminology that is more common among legal scholars, of the norms that confer competences (in public law) or capaci­ties (in private law).

As is well-known, one of the central pillars of Hart's The Concept of Law is that power-conferring rules are seen as statements which cannot be reduced to mandatory norms. Only if we understand power-conferring rules as a special kind of normative statements, according to Hart, we can account for "the dis­tinctive characteristics of law and of the activities possible within its frame­work" (Hart 1994, 41). Such rules, Hart says, "do not impose duties or obliga­tions" (Hart 1994, 27); rather, they establish how one must proceed in order to bring about certain normative changes; for their addressees, they are "more like instructions how to bring about certain results than mandatory impositions of duty." (Hart 1982b, 219); ”[t]hey appear then as an additional element intro­duced by the law into social life over and above that of coercive control" (Hart 1994, 41). All these and many other similar passages to be found in Hart's work suggest that power-conferring rules differ from mandatory norms with respect to their structure, the way in which they contribute to their addressees' practical reasoning, and their impact on social life. However, Hart's work does not offer a fully developed theory of power-conferring rules that would allow us precise­ly to account for them — and for their difference from mandatory norms — with respect to these three perspectives. Besides, in The Concept of Law the distinction between mandatory norms (or 'duty-imposing' norms) and power­conferring rules seems to be wrongly presented as similar to other, not equi­valent distinctions. Thus, Hart uses three different criteria for distinguishing 'primary norms' from 'secondary norms': the first refers to the difference be­tween duty-imposing rules and power-conferring rules; the second to that be­tween rules regulating actions which imply movements or physical changes and rules concerning acts which lead to normative changes; and the third to that between rules about actions individuals should or should not do and rules about rules of the first type. Hart presents these three criteria as interchangeable, that is, as obviously having different connotations, but leading to the same classifi- catory results. But that is clearly not so. To give just one example: The provi­sion contained in art. 53.1 of the Spanish Constitution ordering the legislator to respect the 'essential content' of certain rights and freedoms is a primary rule according to the first criterion, and a secondary rule according to the other two.^[15]