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“The festering issue” – the legality of a second independence referendum

Published: 23 June 2022

Author: David Torrance, House of Commons Library

Cross-posted with permission from the Constitution Unit

With the Scottish Government working towards an independence referendum, discussions continue about the legality of such a referendum. David Torrance, House of Commons Library, examines the "festering issue", arguing that even a consultative referendum could fall outside the scope of the parliament’s powers.

During the House of Lords’ consideration of what would become the Scotland Act 1998, Lord Mackay of Drumadoon (a former Lord Advocate and subsequently a Scottish judge) told peers it would be “perfectly possible to construct a respectable legal argument” that it was within the legislative competence of the soon-to-be-created Scottish Parliament to pass a Bill authorising an independence referendum.

Lord Mackay added that he remained “convinced that the law on this matter should be clarified. If it is not then the festering issue as to whether the Scottish parliament is competent to hold such a referendum will rumble on.” That was arguably a dictionary definition of prescience.

The debate, if not “festering”, does indeed “rumble on” nearly a quarter of a century later, yet much of the commentary seems curiously circular, turning over arguments which might have been relevant in 1998 or 2012 but less so in 2022. Chief among these is the idea that an “advisory” or “consultative” referendum might pass muster if the dispute were to reach the Supreme Court.

But first let us return to the Upper House in 1998. The Lords Sewel and Hardie (respectively a Scottish Office minister and the then Lord Advocate) were clear that an independence referendum Bill would “relate to” the reserved matter of the Union between Scotland and England and would therefore be ultra vires. As Lord Hope later observed, “the Scotland Act provides its own dictionary”.

The Scotland Act 1998

So what does that dictionary say? Under section 29(1), Acts of the Scottish Parliament that fall outwith its legislative competence (or powers) are “not law”. An Act (or a provision thereof) is beyond competence so far as it “relates to reserved matters”. Reserved matters are set out in Schedule 5, Part 1 of which reserves “aspects of the constitution” to Westminster. This includes, among other things, “the Union of the Kingdoms of Scotland and England” and “the Parliament of the United Kingdom”.

The Scotland Act also provides a set of principles to assist the courts when approaching questions of competence (something known as “devolution issues”). Whether a provision of an Act “relates to” a reserved matter is to be determined “by reference to the purpose of the provision, having regard (among other things) to its effect in all the circumstances” (s 29(3)). Section 101 states that in interpreting Acts of the Scottish Parliament, provisions are “to be read as narrowly as is required for it to be within competence, if such a reading is possible”.

In the 2010 case of Martin v Her Majesty’s Advocate, Lord Walker was clear that a provision had to possess “more than a loose or consequential connection” to a reserved matter in order to “relate to” it.

The disagreement

Although the UK and Scottish Governments have long agreed that the Scottish Parliament cannot unilaterally end the Union (i.e. enable Scottish independence) they differed as to the “purpose” and “effect” of referendum legislation in 2012 and continue to disagree a decade later. Importantly, the Edinburgh Agreement of 2012 did not resolve this disagreement but merely paused it with a mutually agreed section 30 Order under the 1998 Act.

As Cormac Mac Amhlaigh has observed, in 2012 the Scottish Government’s reading of s 29(3) of the Scotland Act appeared to be a “narrow” one, in which “the purpose of such a provision would be to hold a referendum”, its “effect in all the circumstances” being null in legal terms.

Indeed, a Scottish Government consultation document published in February 2010 argued that a referendum would “be advisory, in that it will have no legislative effect”, and included a referendum question which was, as a 2012 consultation admitted, “carefully phrased to comply with that requirement”.

The UK government, however, took a “broader level analysis” which argued that a referendum “should not be considered an end in itself, but rather an instrument to achieve a further goal” – that of independence, and therefore something that would not be within devolved competence.

In a January 2012 blog for the UK Constitutional Law Group (UKCLG), seven constitutional academics more or less agreed with the Scottish Government. They argued there was a plausible case that a Bill’s purpose would be to seek “the views of people in Scotland” (rather than legally dissolve the Anglo-Scottish Union) and that a consultative referendum would not “relate to” the reserved matter of the Union because the “weight of authority” (i.e. case law) suggested that devolution statutes ought to be interpreted “generously and purposively” in line with s 101 of the 1998 Act.

This was a reference to the 2002 case of Robinson v Secretary of State for Northern Ireland, which had taken such an approach to the Northern Ireland Act 1998.

Imperial Tobacco

That “weight of authority”, however, then shifted. The UKCLG blog predated the 2012 Imperial Tobacco Ltd v Lord Advocate judgment, which implied a clear distinction between the approach desirable for a statute implementing an international treaty (the Belfast/Good Friday Agreement) and therefore related to political stability in Northern Ireland, and that applicable to resolving the boundary between devolved and reserved matters under the Scotland Act 1998. That Act, concluded the Supreme Court, ought to be interpreted neither expansively nor restrictively, but simply in accordance with the natural meaning of the words used.

The Imperial Tobacco case came to be viewed by constitutional scholars as significant in the context of the disagreement between the Scottish and UK Governments vis-à-vis a second independence referendum. Indeed, subsequent case law (the 2018 Scottish Continuity Bill case and two further references in 2021, one of which interpreted s 101 narrowly) appeared to adhere to its “plain reading” approach. By 2021, Stephen Tierney – one of the principal authors of the 2012 UKCLG blog – concurred.

Legal effect

Some also interpreted an observation in the first Miller case of January 2017 as significant, that the Brexit referendum of 2016 had not changed “the law in a way which would allow ministers to withdraw the United Kingdom from the European Union without legislation”. But, as the Supreme Court added, that “in no way” meant the majority “Leave” vote was “devoid of effect”: “It means that, unless and until acted on by Parliament, its force is political rather than legal. It has already shown itself to be of great political significance.”

The journalist James Forsyth has suggested the UK government is concerned this could allow the Scottish Government to argue that referendum legislation would not “impinge” upon the reserved matter of the Anglo-Scottish Union as it “would have no direct legal effect”.

This, however, ignores s 29(3) of the Scotland Act 1998, which states that whether a provision of an Act “relates to” a reserved matter is to be determined “by reference to the purpose of the provision, having regard (among other things) to its effect in all the circumstances” (author’s emphasis). That would include (as Millermade clear) political as well as legal effect, while the clearly stated “purpose” of a “yes” vote in a referendum would be, to quote the 2011 SNP manifesto, that “Scotland becomes an independent nation”.   

Looked at from this perspective, the “purpose” of an “advisory” or “consultative” referendum would remain that of achieving independence, and it would therefore “relate to” a reserved matter. As Ciaran Martin observed in a Constitution Unit blog last year, the aim of the Scottish government, and the wider nationalist movement, is not to have a referendum. It is to achieve independence.”


Another important case in the context of this debate concerned a “declarator” sought by the pro-independence activist Martin Keatings in early 2021, stating that Holyrood was competent to legislate for a referendum. This was rejected by the Outer House of the Court of Session as “hypothetical” and subsequently also by the Inner House. In his judgment, the Lord President (Lord Carloway) echoed Imperial Tobacco in making clear that the Court’s approach to the Scotland Act would be one of ordinary statutory interpretation:

  • The question would have been whether an Act to hold a referendum on Scottish Independence “relates to” (s 29(2)(b)) “the Union of the Kingdoms of Scotland and England” or “the Parliament of the United Kingdom” (sch 5 part I para 1(b) and (c)) having regard to its effect in all the circumstances (s 29(3)). The Act would relate to these reserved matters if it had “more than a loose or consequential connection with them” (UK Withdrawal from the EU (Legal Continuity (Scotland) Bill 2019 SC (UKSC) at para [27], quoting Martin v Most 2010 SC (UKSC) 40, Lord Walker at para [49]). Viewed in this way, it may not be too difficult to arrive at a conclusion, but that is a matter, perhaps, for another day (author’s emphasis).

Professor Stephen Tierney observed that Lord Carloway was applying the “competence test” as used by the Supreme Court:

  • A provision will be considered to be outside competence if it has more than a ‘loose or consequential connection’ to a reserved matter. The key question for the Supreme Court would be whether a referendum on Scottish independence would have more than such a loose or consequential connection to the Union of the Kingdoms of Scotland and England. It seems probable that it would find such a connection to exist.

The President of the Supreme Court is now Lord Reed, whose track record suggests he would not significantly depart from this approach. As he observed in the Imperial Tobacco case (before it reached the Supreme Court): “The Scotland Act is not a constitution, but an Act of Parliament.”

The debate in 2021-22

The Scottish Government published a Draft Independence Referendum Bill on 22 March 2021. The preamble describes it as an Act of the Scottish Parliament “to make provision for the holding of a referendum in Scotland on a question about the independence of Scotland” while Clause 1(2) states that the question – subject to Electoral Commission approval – will be the same as that in 2014: “Should Scotland be an independent country?” It has yet to be introduced to the Scottish Parliament and needs to be signed off by the Scottish law officers before it is.

While the legality of such legislation might have been an open question in 2012, a decade later there are few constitutional scholars who believe it would pass muster in the Supreme Court – including Stephen Tierney and Aileen McHarg, the main authors of the 2012 UKCLG blog. Only Professor Adam Tomkins (who in 2012 was clear that a such referendum would be ultra vires), believes that is possible if Scottish Ministers are prepared to concede”:

(1) that its purpose is merely to consult the people rather than to make any decision about independence and (2) that its effect is zero, i.e. that no legal or constitutional consequences would attach to any Yes vote.

Concluding remarks

It is important when considering this issue to separate political arguments from legal. Consideration of electoral mandates or the “sovereignty of the Scottish people” are unlikely to detain the Supreme Court for long. Rather they will consider the plain words of the Scotland Act 1998 and relevant case law.

First Minister Nicola Sturgeon stated on Tuesday that if we are to uphold democracy here in Scotland we must forge a way forward, if necessary, without a section 30 Order”. She suggested the Scottish Government’s legal position would be made clear before Holyrood rises for its summer recess on 2 July. Will this be consistent with its 2010-12 stance that an “advisory” referendum would be of no legal effect and therefore not “relate to” a reserved matter? Constitution Secretary Angus Robertson says the intention is to hold the referendum “next October”, so it seems likely we’ll find out soon.

Dr David Torrance is a constitutional specialist at the House of Commons Library. His briefing paper on the legal issues surrounding an independence referendum examines these arguments in greater depth.


Cross-posted with permission from the Constitution Unit

Image by Michaela Wenzler from Pixabay 

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