We need to talk about the referendum... Scotland's membership of the UK in focus

Referenda are very much in the air at the moment: with Greece's Prime Minister first announcing and - then withdrawing - a proposal for a referendum on continued Greek membership of the eurozone; with British Euro-sceptics pressing for a referendum on the UK's continued membership of the EU; and with Scotland's First Minister, Alex Salmond, promising his SNP Party conference a referendum on Scotland's continued membership of the United Kingdom.

The joy of referenda is that they bypass the messy and complex compromises created in and by the mechanisms and institutions of government within Parliamentary democracies, and instead give 'the people' the power to choose.

The underlying premise of referenda is, of course, that it is 'the people' who are sovereign. And this is where the problem with the proposed Scottish referendum on independence comes in. The UK is a unitary state, not a federation. This remains the case even after devolution. Power devolved from the Westminster centre is power retained; rather than power ceded, and sovereignty divided. If the UK, as a constitutional monarchy, allows for the notion of a 'sovereign people', then it encompasses all the peoples of the UK. On this constitutional model, the 'Scottish people' are no more sovereign than the 'people of Basingstoke' or the 'men of Kent' or the 'women of Wales'.

And it is this unitary constitutional model which is reflected in the terms of the Scotland Act 1998 which created the devolutionary structures north of the border. Section 1(1) of that Act provides that "there shall be a Scottish Parliament" because the Crown, acting on the advice of the Westminster Parliament, so wills it; not because the "Scottish people" brought it into being. The Scotland Act modifies the terms, but maintains the fact, of union between Scotland and England: section 37 states that "The Union with Scotland Act 1706 and the Union with England Act 1707 have effect subject to this Act".

Just as the Scottish people are not sovereign, neither is the Scottish Parliament. The Westminster Parliament has set legally enforceable limits on the power of the Scottish Parliament by providing in Section 29 of the Scotland Act as follows:

29.- Legislative competence

(1) An Act of the Scottish Parliament is not law so far as any provision of the Act is outside the legislative competence of the Parliament.

(2) A provision is outside that competence so far as any of the following paragraphs apply-

(a) it would form part of the law of a country or territory other than Scotland, or confer or remove functions exercisable otherwise than in or as regards Scotland,

(b) it relates to reserved matters ...

And Paragraph 1 of Schedule 5 to the Scotland Act states that:

The following aspects of the constitution are reserved matters, that is-

(a) the Crown, including succession to the Crown and a regency,

(b) the Union of the Kingdoms of Scotland and England,

(c) the Parliament of the United Kingdom"

So any Act of the Scottish Parliament which "relates to" the union between Scotland and England, or the constitutional position of the Crown or the UK Parliament, will simply not be law because any such Act would be outside the legislative competence of the Scottish Parliament to pass.

On the face of it, this presents an insurmountable legal obstacle to the Scottish Parliament enacting any law which would provide for an independence referendum to be held in Scotland. How else might any such measure, in terms of both its purpose and effect (see Martin and Miller v HM Advocate [2010]), be described other than as "relating to" these reserved aspects of the constitution ? As Lord Sewell, the promoter of the Scotland Bill in the House of Lords, advised Parliament:

"[A]s the Bill stands the Scottish Parliament will not be able to legislate to hold a referendum on independence as the union of the kingdoms is already a reserved matter. .... [L]egislation for a referendum on independence would be legislation about whether the Union should be maintained and so be beyond the competence of the [Scottish] parliament."

Further, the decision of the UK Supreme Court in AXA General Insurance Limited and others v The Lord Advocate and others [2011] has radically loosened the requirements of standing in public law cases in Scotland such that now any individual or group with a sufficient interest may bring a petition for judicial review to the Court of Session in order to prevent a breach by a public body of a duty owed by that body to the public, even where the excess or misuse of power affects the public generally.

The AXA case itself involved proceedings challenging the lawfulness of an Act of the Scottish Parliament which had been passed on 11 March 2009, received the Royal Assent on 17 April 2009 and come into force on 17 June 2009. These court proceedings, which were ultimately unsuccessful, involved two and half years of litigation from the initial hearing before the judge at first instance to the final decision of the UK Supreme Court (and that was considered by normal Scottish standards, to have been completed within record time).

The Scottish Government is well aware of the potential for legal challenge to any independence referendum Bill brought before - or Act passed by - the Scottish Parliament. But it may be that in pressing forward with legislation that is certainly open to such challenge - and which has a high chance of being struck down by the courts as not law - political advantage may be sought to be drawn from it. The issue of the lawfulness of any independence referendum measure will ultimately have to be determined by the UK Supreme Court.

But both the First Minister, Alex Salmond and the Scottish Cabinet Secretary for Justice, Kenny MacAskill have 'form' in relation to role of the UK Supreme Court in Scottish matters. The latter has said: "we're undermined routinely by a court that sits in another country and is presided over by a majority of judges who have no knowledge of Scots law, never mind Scotland.... a court in London that is made up of a majority of judges who do not know Scots Law, who may have visited here for the Edinburgh Festival."

The former, defending these remarks, has said: "you need a succession of incidences of things that are happening before the extent of the encroachment and the vulnerability of the [Scottish] Parliament really hits home... If we are to be scrutinised in terms of the overall scrutiny then let it be by the [European] court [of Human Rights] that scrutinises another 47 jurisdictions and not by the Supreme Court in England..."

Ultimately, the only way to be sure that a referendum can lawfully be held on the question of the dissolution of the union between Scotland and the rest of the UK would be for the Westminster Parliament to pass the necessary legislation. But if a referendum is indeed properly to be understood as a consultation with the 'sovereign people' to which Parliament is answerable, then any such 'dissolution referendum' cannot be confined to a consultation with the people of Scotland alone but must properly extend to all the peoples of the UK - not least because Scottish independence will have profound effects on their own future politics (notably as regards the loss of the block Scottish Labour, or anti-Tory vote in Westminster).

It is not inconceivable that the result of any such UK-wide referendum would be that the electorate in England (fed on tales of their constant subsidising of Scottish spending, and wearying of the anti-English sentiment that lies beneath so much Scottish public discourse) would vote in favour of the dissolution of the Union, while a majority of the Scottish electorate would balk at independence.

In this way might the SNP's primary political aim be achieved, even against the wishes of the Scottish people. That's why we need to talk about the referendum.

Aidan O'Neill QC is a barrister at Matrix Chambers. The UKSC blog, which provides commentary on the UK Supreme Court and its judgments, was created by lawyers and barristers from Olswang and Matrix. Click here to visit the blog and click here to follow the UKSC blog on Twitter.