The Conservative party’s proposal to repeal the Human Rights Act (and their proposal’s many faults) has already been well documented. However, the European Union is just as much a target of indignation for conservative and other eurosceptics, and David Cameron has promised, if re-elected, an in-out referendum by 2017, if the terms of Britain's EU membership cannot be renegotiated. With UKIP support gaining in the polls, pressure is growing on other parties to support an EU in-out referendum. There is a realistic prospect that the UK may leave the EU.
There are many arguments that can be made as to why the UK should remain within the EU. This posting addresses just one: the serious constitutional consequences for both the constituent parts of the UK, and the UK as a whole, should there be a ‘Brexit’. Given that the UK has just survived perhaps the most serious threat ever to its constitutional existence, in the form of a very closely run Scottish referendum on independence, and given the fervent and almost desperate nature of the ‘Vow’ made by all three party leaders to accord greater powers to Scotland if necessary to maintain the Union, the risk of such further constitutional instability should be taken seriously.
At first it might seem that Scotland’s ‘No’ vote for independence would lessen the chance of EU secession, given the relatively greater pro-EU vote in Scotland. How each constituent part would vote is not certain, but in 2012, 53% of Scots said they would vote to stay in the EU, compared with a third who said they would vote to leave. This was in contrast to attitudes in England, where 50% said they would vote to leave the EU compared with 42% who would vote to stay in. At the last European Parliament elections in May 2014, UKIP gained the largest percentage of votes in the UK overall, with 27.5%, but in Scotland only 10.46% of the vote. Furthermore, EU regional funding tends to benefit Scotland, Wales and Northern Ireland more than it does England. Wales and Northern Ireland are net recipients from the EU Budget, and in particular, Northern Ireland stands to lose significant sums if the UK withdrew from the EU. Likewise, to the extent that the devolved nations have access to EU institutions in areas of devolved competence, they enjoy an international presence that would be difficult to replicate through country-specific diplomatic missions. So there are distinct advantages to be lost by an EU exit.
However, the relatively lower eurosceptic vote in the devolved nations would not make a great impact on an EU in-out referendum overall, given that the population of the devolved nations eligible to vote is small compared to that in England. How much does this matter? It matters a great deal if the vote in the devolved nations is of a less eurosceptic complexion than the English vote in an EU in-out referendum.
It is with the devolution settlement itself that an EU exit would wreak the most havoc, risking a constitutional crisis. Both the European Convention on Human Rights (ECHR) and EU law are incorporated directly into the devolution statutes in Scotland, Wales and Northern Ireland. For example, section 29(2)(d) of the Scotland Act 1998 (SA), provides that Acts of the Scottish Parliament that are incompatible with EU law or with ECHR rights are ‘not law’. Section 108(6) Government of Wales Act 2006 states that any act of the Welsh Assembly incompatible with EU law or the ECHR, falls outside its competence. Section 24 of the Northern Ireland Act prohibits any legislation contrary to EU or ECHR law.
Therefore, although the Westminster Parliament may repeal the Human Rights Act 1998 or the European Communities Act (ECA) 1972, this would not bring an end to the domestic incorporation of the ECHR or EU law in devolved nations. It would still be necessary to amend the relevant parts of devolution legislation. But this would be no simple matter and could lead to a constitutional crisis. Although the UK Parliament may amend the devolution Acts, the UK government has stated that it will not normally legislate on a devolved matter without the consent of the devolved legislature. This requires a Legislative Consent Motion under the Sewel Convention. However, the devolved legislatures might be reluctant to grant assent, especially as one feature of the ‘Vow’ made to the Scottish electorate was a commitment to entrench the Scottish Parliament’s powers, thus giving legal force to the Sewel Convention. So the need to amend devolution legislation renders a UK EU exit constitutionally highly problematic.
Should devolved nations be able to host separate referenda?
Would it be possible for the devolved nations to demand their own referenda in the event of a Westminster mandated EU in-out referendum? In the frenzied last days before the Scottish independence referendum, there was talk of moves towards a ‘federal’ UK. This does not seem very likely now, and whatever recommendations the Smith Commission will deliver later this year (which are likely to include more financial, welfare and taxation powers for the Scottish Parliament) they are unlikely to include greater autonomy in foreign affairs. However, as many areas of EU competence are devolved matters, and continued Scottish membership of the EU was a concern in the event of Scottish independence, the matter is likely to be of great interest in Scotland. Notably, between the 2015 UK general election and the promised 2017 EU in-out referendum will come another election - the 2016 Scottish parliamentary elections. The SNP may perform well in that election, bolstered by the 45% vote in the independence referendum and progress toward ‘devo max’. In which case, the Edinburgh government - which is generally of a more pro-European and social-democratic hue than Westminster – might call for a new independence referendum if there were a serious prospect of a 2017 referendum leading to a UK EU exit, presenting such a further independence referendum as Scotland’s means of remaining within the EU. And given this change of circumstances they might gain over 50% of the vote. This would not find favour in London, which would almost certainly not accord a repeat referendum the sanction of legitimacy accorded to the 2014 vote. However, regions have been willing to go ahead with referenda even without a constitutional sanction – such as Catalonia this November.
In the face of such a prospect, should a potential EU in-out referendum be required to take on a different constitutional form to past UK-wide referenda? Should a requirement be set for a majority of exit votes in each of the devolution jurisdictions before UK withdrawal is possible? Or perhaps each of the devolved nations should be able to hold its own in-out referendum, and a ‘federal’ standard set whereby UK withdrawal is only possible if a majority of the devolved nations vote to exit?
Scotland and the sovereignty question
A British exit from the EU is sometimes justified in terms of the maintenance of parliamentary sovereignty, which presently must concede the supremacy of EU law (acknowledged both in ECJ caselaw such as Costa v ENEL, and s 2(4) ECA). However, the Diceyan orthodoxy of parliamentary sovereignty has never held as much weight north of the border. In the 1953 case of MacCormick v Lord Advocate in the Court of Session, the Lord President, Lord Cooper, (a former Conservative and Unionist politician and eminent legal historian) contested the Diceyan orthodoxy thus:
‘The principle of the unlimited sovereignty of parliament is a distinctively English principle which has no counterpart in Scottish constitutional law....Considering that the Union legislation extinguished the parliaments of Scotland and England and replaced them by a new parliament, I have difficulty seeing why it should have been supposed that the new parliament of Great Britain must inherit all the peculiar characteristics of the English parliament but none of the Scottish parliament, as if all that happened in 1707 was that Scottish representatives were admitted to the parliament of England.’
Linda Colley's well-known work, Britons: Forging the Nation reminds us that both the British state and the British national identity were ‘forged’ by the Acts of Union of 1707. The United Kingdom is only 300 years old, not an ancient natural phenomenon, and it may be undone. Given that the Union of 1707 brought into being the British state, ought we not give this historical event of the Acts of Union its due as a keystone of the British constitution, rather than the Diceyan mantra of parliamentary sovereignty? In which case, perhaps we should recognise that the British constitution is not simply the English constitution, and that Scottish constitutional principles (and Northern Irish, and even now nascent Welsh) play their part in a multiple constitutional order, and may be of particular salience at times of crisis or ‘constitutional’ moments, such as the issue of whether to withdraw from the EU. Scottish intellectuals, lawyers and politicians of many different political persuasions stand by an indigenous Scottish tradition of popular sovereignty that is claimed to date back to the Declaration of Arbroath in 1320. They hold that, before the 1707 Act of Union, sovereignty resided in the Scottish people - and that it still does so, in spite of the claims of Diceyan parliamentary sovereignty.
Many Scottish unionist politicians accept the doctrine of Scottish popular sovereignty. It was this doctrine that pervaded the Claim of Right for Scotland in 1989, which was signed by the great majority of Scotland's MPs and many of the leaders of Scottish civil society. The draft Constitution for an independent Scotland, published earlier his year, stated that ‘the fundamental principle’ that ‘the people are sovereign…resonates throughout Scotland’s history and will be the foundation stone for Scotland as an independent country’.
Therefore, meditation on the entirety of the Union, and its constitutional basis, poses the question of whether, at least in Scotland, the doctrine of popular sovereignty might form the basis of Scotland’s own right to determine whether or not it exits the EU. If Scotland chose to remain, and England to leave, the scope for constitutional crisis would be extreme.
Impact on Ireland and the Northern Ireland peace process
Lastly, the impact on the island of Ireland of a UK exit from the EU should be considered. It could well be source of great instability. Although Ireland itself is clearly a separate state, and has long since left the UK, it is nonetheless in a somewhat different relationship to the UK than the other current 26 members of the EU. Section 2(1) of the Ireland Act 1949 (the British Act of Parliament passed to deal with the consequences of the Irish Republic of Ireland Act 1948) declared that, even though the Republic of Ireland was no longer a British dominion, it would not be treated as a ‘foreign country’ for the purposes of British law. Irish and UK history are much intertwined and, were the UK to exit the EU, it would mean an external border of the EU would run through the island of Ireland. The shared border with the Republic of Ireland has long been of enormous symbolic and practical importance. What would happen to the Common Travel Area between the two islands if the UK exited the EU? Would visa requirements and customs duties be imposed?
The Belfast or ‘Good Friday’ Agreement of 1998, an international treaty signed by the UK and Republic of Ireland, enshrined North-South and East-West co-operation, effected constitutional changes and established cross-border bodies. It includes many provisions concerning EU and ECHR law, and the status of the UK and Ireland as EU member states is woven throughout the Agreement. Indeed, the section entitled ‘Agreement between the Government of the United Kingdom of Great Britain and Northern Ireland and the Government of Ireland’ speaks of ‘close co-operation between (the) countries as friendly neighbours and as partners in the European Union’. The Good Friday Agreement required the British government to incorporate the ECHR into Northern Ireland law. Any amendment through changes to either the Human Rights or Northern Ireland Acts which did not meet the human rights commitments in the agreement would be incompatible with this international treaty. The peace process in Northern Ireland is unfortunately not irreversible, but it has been unforgivably ignored in UK discussion on whether to withdraw from the EU. It is also likely to be ignored in Brussels, where there is some impatience with British demands in any case.
In March 2012, a joint Statement by Taoiseach Enda Kenny and Prime Minister David Cameron set out a programme to reinforce the British-Irish relationship over the next 10 years. It emphasised the importance of shared common membership of the EU for almost forty years and described them as ‘firm supporters of the Single Market’. However, a UK EU exit would have consequences for the future of the Belfast agreement and in particular implications for Anglo-Irish co-operation in dealing with cross-border crime and terrorist activity. To give just one example: the UK and Ireland make frequent use of the European Arrest Warrant (EAW). Figures indicate that since the EAW entered into force, the great majority of requests made by Northern Ireland for surrender of persons have been to Ireland. Prior to the introduction of the EAW, a number of European and domestic measures in the UK and Ireland regulated extradition proceedings, and resurrecting these would be a painful process, fraught with difficulties and uncertainties and potential for endless litigation. While the EAW has not always functioned ideally, a return to bi-lateral extradition conventions and other measures would be very undesirable.
In conclusion, a British exit from the EU risks undermining the very self-determination and national sovereignty that its adherents believe it will bring about. This is because it risks shattering the fragile balance and stability of the UK by threatening the peace settlement in Northern Ireland and raises the possibility of a further independence referendum in Scotland. Surely such constitutional risks are not to be taken on lightly? But at present, there is little indication that anyone calling for an EU exit is giving them much thought.
Sionaidh Douglas-Scott is Professor of European and Human Rights Law at the University of Oxford.
 ‘Relatively greater,’ given that UKIP did gain one Scottish constituency in the 2014 European parliamentary elections.
 House of Commons Library, research paper 13/42 ‘Leaving the EU’ at 92.
 ‘Leaving the EU’ at 44.
 The official number of registered electors qualified to vote in Parliamentary elections are: England - 38,837,300; Wales - 2,301,100; Scotland - 3,985,300; and Northern Ireland - 1,230,200. Office for National Statistics, Electoral Statistics for UK – 2012, available at http://www.ons.gov.uk/ons/rel/pop-estimate/electoral-statistics-for-uk/2012/stb---2012-electoral-statistics.html#tab-Parliamentary-Electors
 The Smith Commission website is accessible here: https://www.smith-commission.scot/
 MacCormick v Lord Advocate 1953 SC 396, 1953 SLT 255.
 L Colley, Britons: Forging the Nation, 1707-1837 (Vintage: 1996).
 See for example, the ‘Welsh Byelaws’ case: Attorney General v National Assembly for Wales Commission and others  UKSC 53.
 The UK’s current plans are to exercise a block opt-out from over 130 EU Justice and Home Affairs measures but to opt back in to the EAW immediately.