Kenneth Campbell QC: How Devolution Has Altered Some Fundamentals of the British Constitution


Regular readers of this blog will need no reminding of how much anticipation has been devoted to the Art 50 litigations ahead of and and during  the UK Government’s appeal to the UK Supreme Court, in what has been by turns both an attempt to work out the boundaries of the constitution, and a glimpse of the constitution at work.

What has been under-analysed in the run-up to the appeal hearing is the devolution dimension. During the hearing too, there was at times a sense that its relevance to the issue was not immediately clear to some participants. This post seeks to address the wider effect of devolution on the constitution, as that has been made clear during argument in Miller and McCord.

It is almost 20 years since the first tranche of devolution legislation, and as is well known, there have been several further rounds at different times in each devolved nation, each driven by factors specific to that nation. Their cumulative effect, however, has been to alter the UK constitution, and it is suggested that, perhaps until the hearing in the UKSC, the full implication of the effects of devolution on the wider British constitution have not been as widely appreciated as perhaps they ought. Two instances may serve to illustrate this: the Sewel convention about legislative consent, particularly in Scotland, and the multi-dimensional character of Northern Irish devolution.

Sewel convention

In its essence, the Sewel convention in now well known. In the reserved powers model  of devolution adopted for Scotland, and in a more complex form for Northern Ireland, and which will also be the ultimate model for Wales, there is a clear overlap of competence between the centre and the devolved legislature. The convention states that the  UK Parliament will not normally legislate in an area of devolved competence without the consent of the devolved legislature, nor will it legislate to alter the structure of devolution without such consent. Leaving to one side the scope of ‘normally’, which generated some heat but little light during the appeal, the broader question is one of effect.

Constitutional conventions do not generally have legal effect, of course, and on one view, therein lies their value. On the other hand, all constitutions with sub-state units exercising legislative and executive powers entail a boundary with the centre. Some form of boundary recognition and means for managing boundary conflicts is essential. The Sewel convention forms part of that mechanism in the British constitution. Whether or not it is also a nod to the notion of the legislative supremacy of the UK Parliament is another matter, though that is arguably built into the UK model of devolution.

Embodied in a constitutional convention, it is arguable that the political dimension of the constitution takes primacy over the legal. But in the case of Scotland, that is no longer so: section 2 of the Scotland Act 2016 amends the existing scheme of competence, and adds the following to section 28 of the Scotland Act 1998 after a reservation of power for the UK Parliament to legislate in devolved areas:

“(8) But it is recognised that the Parliament of the United Kingdom will not  normally legislate with regard to devolved matters without the consent of the Scottish Parliament.”

In other words, the general legislative consent part of the convention is now given statutory force as regards Scotland, though the part relating to the alteration of the structure of devolution is not mentioned. I have argued previously on this blog and elsewhere that this must be understood as having more than symbolic effect. In short, the position is that  the section does act as a fetter on the UK Parliament, and does so both because the circumstances of enactment make that clear, and because as a matter of statutory interpretation, every provision in an Act is intended to create legal effects. That is all the more so when it is recalled that section 1 of the Scotland Act 2016 enacts (by adding a new section 63A to the existing scheme of the Scotland Act 1998) that the Scottish Parliament and the Scottish Government are “a permanent part of the United Kingdom’s constitutional arrangements” and fences that provision with manner and form restrictions on repeal in the shape of the requirement in new section 63A(3) that the institutions may not be abolished “except on the basis of a decision of the people of Scotland voting in a referendum”. It is difficult to conceive of this series of provisions as not amending the UK constitution, both as regards Scotland and as regards the UK Parliament.

Although the UKSC ‘struggled’ with the effect of the Sewel convention on the Art 50 challenge (Lord Reed, day 3 transcript p 157), the Lord Advocate argued that all four legislatures were entitled to a voice in a decision altering the constitution because of the effect  on legislative competence which would follow (day 3 transcript, pp 157-8), under reference to Lord Reed’s judgment in Imperial Tobacco. The question to be resolved on this aspect of the case is whether the Art 50 notification is an act which involves legislation with regard to devolved matters (cf. day 3 transcript, pp 160-161).

The constitution and Northern Ireland

Turning to the structure of devolution in Northern Ireland, it will be recalled that while the Northern Ireland Act 1998 lays out arrangements for executive and legislature, there are several dimensions to the overall structure. These include the Belfast Agreement (also known as the Good Friday Agreement), which the Attorney General for Northern Ireland argued in McCord was not an international treaty (and indeed that it had no force in domestic law either). However, the fact that the Agreement was concluded between two sovereign states, that it speaks of undertakings and binding obligations, and that it has been registered with the UN is highly suggestive that it is a treaty in international law. An indication of the Agreement’s effect in domestic law can be gauged from the long title of the Northern Ireland Act 1998:

“An Act to make new provision for the government of Northern Ireland for the purpose of implementing the agreement reached at multi-party talks on Northern Ireland set out in Command Paper 3883.”

The arrangements brought into effect by the 1998 Act have had judicial consideration at the highest level as long ago as 2002. In Robinson v Secretary of State, the House of Lords recognised that the Northern Ireland Act 1998 was a constitutional statute, and further that

“The 1998 Act does not set out all the constitutional provisions applicable to Northern Ireland, but it is in effect a constitution. So to categorise the Act is not to relieve the courts of their duty to interpret the constitutional provisions in issue. But the provisions should, consistently with the language used, be interpreted generously and purposively, bearing in mind the values which the constitutional provisions are intended to embody.” [Lord Bingham, para 11]

Lord Hoffman agreed on the constitutional status of the Act, and went on to deal with the agreement:

“…it is necessary to have regard to the background to the 1998 Act. It was passed to give effect to the Belfast Agreement concluded on Good Friday 1998. This agreement was the product of multi-party negotiations to devise constitutional arrangements for a fresh start in Northern Ireland. A key element in the agreement was the concept of decisions being made with cross-community support, that is, by representatives of majorities of both the unionist and nationalist communities. The 1998 Act is a constitution for Northern Ireland, framed to create a continuing form of government against the background of the history of the territory and the principles agreed in Belfast.” [para 25]

Here too it will be seen that in relation to devolved matters, there is sophisticated decision making structure. It is one designed to facilitate cross-community, and cross-border engagement. Further, it is suggested that, like the Scots devolution structures, these arrangements for Northern Ireland too have a permanence subject only to manifestations of the will of “a majority of the people of Northern Ireland” voting in a poll “that Northern Ireland should cease to be part of the United Kingdom and form part of a united Ireland” – Northern Ireland Act 1998, section 1. This was explored in argument before the UKSC by the Northern Ireland claimants, with reference to the implications of EU policies on a cross-border or all-Ireland basis implicit in the Agreement (day 3 transcript, pp 121, 138). Further, there was an explicit challenge to the continued existence of unalloyed parliamentary sovereignty in light of what was said to be the effective transfer of sovereignty over constitutional change to the people of Northern Ireland by virtue of section 1 (day 3 transcript, pp 133-4).


Miller and the other Art 50 cases raise a number of questions about the operation of the British constitution. It is suggested that in the hearing before the UKSC the shape of the separation of powers part of the UK constitution has come into focus. As in every controversy where the place of the UK Parliament is in question, Dicey was invoked, almost ritually. That is done sometimes without regard to his actual words, and more to the point, without much regard to whether his conception of parliamentary sovereignty remains sound. I have argued elsewhere that its basic premises can no longer be considered a complete account. It is suggested that whatever else the Art 50 cases show, they demonstrate devolution has altered the constitution more widely. That is obvious in the devolved institutions now in place in Scotland, Wales and Northern Ireland, but the signal service which the Art 50 appeals have done is bringing to a wider legal public the corollary, which is the limits which, it is suggested, are also placed on the central institutions of the constitution. There are obviously effects flowing from the description of the boundaries as between centre and devolved nations; however, it is strongly arguable that these effects reach further into the tissue of the constitution, and also bear on action at the centre which may or does affect devolved competence. In other words,  devolution not only defines the powers of the devolved administrations, but the manner in which the structures of devolution have developed now constrains action at the centre too. The British constitution is an evolving matrix, and the only surprise is that it has taken these appeals to lay this process open to a wider audience.

Kenneth Campbell QC is an Advocate at Arnot Manderson Advocates, Edinburgh, a Barrister at Lamb Building, London and doctoral researcher at Edinburgh University Law School.

(Suggested citation: K. Campbell, ‘How Devolution Has Altered Some Fundamentals of the British Constitution’, U.K. Const. L. Blog (20th Jan 2017) (available at