ABSTRACT
This chapter explains the early origins and constitutional importance of the separation of powers. The separation of powers, together with the rule of law and parliamentary sovereignty, runs like a thread throughout the constitution of the United Kingdom. In order to evaluate the extent to which the separation of powers applies, and the many exceptions to the pure doctrine, it is necessary first to define the major institutions of the state and evaluate the relationship between them. In order to do this, the chapter examines the following relationships: the executive and the legislature; the legislature and the judiciary; and the executive and the judiciary. The separation of powers doctrine does not insist that there should be three institutions of government each operating in isolation from each other. Indeed, such an arrangement would be unworkable, particularly under a constitution dominated by the sovereignty of Parliament.
