Abstract
The normal way to establish that a person has authority over another requires a rule-governed institutional setting. To have authority is to have power, in the juridical sense of the term, and power can only be conferred by norms constituting it. Power-conferring norms are essentially institutional, and the obligation to comply with a legitimate authority's decree is, first and foremost, institutional in nature. The main argument presented in this essay is that an explanation of practical authorities is a two-stage affair: the special, practical import of an authority can only be explained against the background of an institutional setting which constitutes the authority's power and the corresponding obligation to comply. However, this obligation is not an all things considered obligation, it is conditioned on reasons to participate in the relevant institution or practice