The separation of powers

The doctrine of the separation of powers is usually attributed to the 18th century French political philosopher Montesquieu, and more particularly to his book L’Esprit des Lois, although the origins of the idea can actually be traced back to classical antiquity.

The doctrine divides all forms of power exercised by the state into three categories, namely legislative, executive and judicial, with the nature of each being as follows:

legislative power involves making law;

executive power involves administering the law, in the sense in which governmental agencies and officials administer it; and

judicial power involves interpreting and applying the law in the sense in which the courts interpret and apply it.

Having identified these three types of power, the doctrine then requires that no more than one type should be exercised by a single body or official. So, for example, the legislature that makes the law should not also interpret it and apply it in individual cases. Similarly, executive bodies and officials who administer the law should not have the power to make authoritative decisions as to what the law means and how it is to be applied in individual cases. Furthermore, the courts which interpret and apply the law should not also make it.

Although it is important to note that the British constitution has never reflected this strict version of the doctrine, the basic idea of the separation of powers retains considerable practical importance in several ways. One of the most obvious examples of this importance lies in the field of judicial review (which, as we will see at p.

The case was one of several similar ones in which the court was concerned with the refusal of local authorities to renew expiring sex shop licences that had been granted under statutory powers. In each case, the local authority had concluded that the appropriate number of sex shops in the relevant area was nil, and therefore all applications for licences would be refused, even though, on the facts of each of the cases which were before the court on this occasion, there had been no change of circumstances since the previous licences had been granted.

The court held that when considering an application for renewal of a sex shop licence, a local authority must have regard to the fact that a licence had previously been granted. However, provided it does have regard to this fact, its decision to refuse to renew a licence will not be perverse simply because there has been no change in the character of the relevant locality or in the use to which any premises in the vicinity are put.

The crucial point in the court’s approach to cases such as this is that the legislature is not only supreme but must also be taken to know that a local authority is a democratically elected body, whose membership changes from time to time in line with the changing views of the local electorate. It is not surprising, therefore, that what is ‘appropriate’ may be perceived differently by different elected representatives at different times. Equally, it is not surprising that the court, being aware of the doctrine of the separation of powers, should decide not to intervene.

Although the constitutional basis of the Birmingham case is readily apparent, the courts are also clearly aware that there are cases where the doctrine of the rule of law does require them to intervene.

It is a contradiction in terms to create a [decision-maker] with limited jurisdiction and unlimited power to determine such limit at its own will and pleasure – such a [decision-maker] would be autocratic, not limited …

Nevertheless, the court remains conscious that its constitutional role is limited. For example, in R v Hillingdon London Borough Council ex parte Puhlhofer [1986] AC 484, which arose in the context of local authorities’ statutory duties in cases of homelessness, Lord Brightman said (at p. 518):

My Lords, I am troubled at the prolific use of judicial review for the purposes of challenging the performance by local authorities of their functions under the Act … Where the existence or non-existence of a fact is left to the judgment and discretion of a public body and that fact involves a broad spectrum, ranging from the obvious to the debatable to the just conceivable, it is the duty of the court to leave the decision of that fact to the public body, save in a case where it is obvious that the public body, consciously or unconsciously, are acting perversely.

Perhaps the most important thing for you to take away from the discussion so far is that, when it comes to real cases, there is often a degree of tension between the basic doctrines underlying the British constitution. When should the courts be primarily conscious of their limited status according to the doctrines of the legislative supremacy of Parliament and the separation of powers, and therefore refuse to intervene in a particular case? Alternatively, when should they assert themselves as the guardians of the rule of law? Finally, to what extent is it relevant – as will often be the case – that the decision-maker, whose conduct has resulted in the case being brought to court, is democratically accountable? (In other words, when should the court take the view that the existence of a political mechanism of control is sufficient to justify the court in refusing a legal remedy?)

The limited nature of the separation of powers in the British constitution

So far we have mentioned only in passing that the British constitution does not reflect a strict version of the doctrine of the separation of powers.

the status of the Appellate Committee of the House of Lords as the highest court of appeal in the English legal system (before it was replaced by the Supreme Court in 2009);

the domination of the legislature by the executive; and

the power of the courts to make law through the doctrine of binding precedent.

Secondly, we can develop a point that we made when discussing the meaning of the word Parliament (see p. 37). As a matter of political reality, all members of the government (or, to use the terminology which better fits the separation of powers, the executive) will sit in Parliament (or, again to use the terminology which better fits the separation of powers, the legislature). Furthermore, the vast majority of them will sit in the House of Commons. In other words, the political party which forms the government will usually dominate the House of Commons, and will, therefore, also effectively dominate the legislative process. The only exception to this proposition is that a government with only a very small (or perhaps even non-existent) majority in the House of Commons will be very dependent on the loyalty of its back-benchers.

Starting with the Appellate Committee of the House of Lords, no strict version of the doctrine of the separation of powers could have tolerated the degree of overlap between the legislative and judicial functions which inevitably flowed from having a committee of one of the Houses of Parliament also functioning as a court. With the coming of the Supreme Court this is, of course, no longer an issue, but the enduring authority of the House of Lords’ decisions makes it worthy of notice nevertheless.

Thirdly, the courts (that is to say, the judiciary) make law (that is to say, they legislate) through the doctrine of binding precedent. However, as we shall be considering this doctrine more closely in Chapter 7, we will say no more about it at this stage.

Clearly, therefore, there are various ways in which the functioning of the separation of powers as an underlying doctrine of the British Constitution has not always been, and still is not, as straightforward as it may appear to be at first sight. However, all those bodies and officials who perform public decision-making functions are aware of the terms of the doctrine, and will, despite its qualified nature in the British context, treat it as constraining their freedom of action in at least some contexts.