The Efficacy Condition

Abstract

A legal system exists, Joseph Raz claims, if and only if it is in force. By this he means to suggest that the efficacy of law-that is, its capacity to control the population to which it applies-is necessary for its identity as such. Despite widespread recognition that efficacy is a condition of the existence of law, however, little time has been spent analyzing the notion. This article begins an attempt to make up the deficit. I make the case for efficacy as necessary for law and go on to develop and defend an account of the concept that is broadly Kelsenian in spirit. In doing so I address questions concerning the relationship between obedience and enforcement in an account of the existence of a legal system as well as relating the discussion to that concerning the ontological status of international law.