ABSTRACT
The separation of powers, together with the rule of law and parliamentary sovereignty, runs like a thread throughout the constitution of the United Kingdom. It is a doctrine which is fundamental to the organisation of a state – and to the concept of constitutionalism – in so far as it prescribes the appropriate allocation of powers, and the limits of those powers, to differing institutions. The concept has played a major role in the formation of constitutions. The extent to which powers can be, and should be, separate and distinct was a central feature in formulating, for example, both the American and French revolutionary constitutions. In any state, three essential bodies exist: the executive, the legislature and the judiciary. It is the relationship between these bodies which must be evaluated against the backcloth of the principle. The essence of the doctrine is that there should be, ideally, a clear demarcation of functions between the legislature, executive and judiciary in order that none should have excessive power and that there should be in place a system of checks and balances between the institutions. However, as will be seen, there are significant departures from the pure doctrine under the United Kingdom’s constitution, and it must be conceded that, while the doctrine is accorded respect, it is by no means absolute.
