Prelude to the Separation of Powers

This article is an exploration of the concept of the separation of powers. It does not seek to advance a fully formulated account of the doctrine; rather, it seeks to show what the many different interpretations of the concept have in common, and defend the validity of a diversity of conceptions. The essence, though not the whole, of separation of powers lies in the meeting of form and function; the matching of tasks to those bodies best suited to execute them. The core of the doctrine is not liberty, as many writers have assumed, but efficiency. This article will attempt to show the considerations generated by the separation of powers when the concept is animated by a thin political theory, that is, principles which are so uncontroversial virtually all political theorists would endorse them. Relying on these thin normative assumptions, the article will examine how far it is possible to claim that the structures of the courts and the legislature have implications for the tasks that ought to be assigned to them; how far a link can be drawn between the institutions of the legislature and judiciary, and the legislative and judicial function. Though the considerations identified are of weak force, their strength is such that they will continue to apply once a thicker normative theory is introduced. By adopting thin normative assumptions we are able to identify the structural concerns that are at the core of the concept, even if they are too shallow to allow us to build a complete model of the separation of powers. This paper should now be read alongside Barber, 'Self-Defence for Institutions'.