It would be an understatement to describe the result of the referendum on the UK's membership of the European Union as giving rise to (what constitutional expert Richard Gordon QC describes as) a 'constitutional moment', where the political climate presents the necessary conditions for fundamental alterations to the UK's constitution. The result risks throwing the UK's constitution into an unprecedented state of flux and confusion, with a number of fundamental questions unanswered. In this article, we outline some of the main legal and political issues to be resolved.
International treaties only take effect in UK domestic law when incorporated and ratified by Parliament. This is in accordance with Section 20 of the Constitutional Reform and Governance Act 2010, and in deference to the doctrine of parliamentary sovereignty which is one of the cornerstones of the UK constitution. Parliamentary sovereignty holds that Parliament is the UK's supreme law-making authority, and while the absolute nature of the doctrine has been called into question (not least by the practical supremacy of EU law), it remains at the core of the UK's uncodified constitution. Parliament makes the law, and the courts interpret it.
While in 1972 the Heath government negotiated the UK's accession to what was then the European Economic Community (which became the EU in 1993 as a result of the Maastricht Treaty) using treaty-making powers under the royal prerogative it was not until Parliament passed the European Communities Act 1972 ('ECA') that the substance of the EU treaties became part of UK law. These include the rights of free movement of people and goods, as well as the panoply of EU legislation.
According to the House of Commons library, there is no completely accurate way to quantify how much EU legislation has become part of domestic UK law by virtue of the ECA. What is known is that several thousand pieces of primary and secondary legislation have incorporated EU obligations into domestic law, while a substantial number of EU directives have 'direct effect', being directly part of UK law without requiring separate domestic legislation. In addition, the jurisprudence of the European Court of Justice (the highest court in the EU) regarding questions of EU law is also part of UK domestic law until the UK formally leaves the EU.
Under the now familiar Article 50 of the Lisbon Treaty, a member state may withdraw 'in accordance with its own constitutional requirements' by giving notice of its intention to leave the EU, at which point it has two years to negotiate the terms of its exit. If a settlement agreement is not reached within two years, every member state must agree an extension, or the member state will leave the EU without any concluded agreement. The effect of the expiry of the negotiation period is that it acts as a 'guillotine', whereby the EU treaties cease to apply in the state in question. Anyone paying even a passing regard to the news will appreciate that the question of what the UK's negotiation platform is, and what result it might expect from a potentially hostile EU, are unclear.
Is the result of the referendum binding?
Legally, the referendum result is not binding and is only 'advisory'' since the enabling legislation (the European Union Referendum Act 2015, 'EURA') mandated only that there would be a referendum on the UK's membership of the European Union. It did not provide that the effect of this would be that the ECA would be repealed, or that a vote to leave the EU would in and of itself automatically trigger a notification under Article 50. This means that the ECA and the vast array of legislation made under it remains part of domestic law, and that EU law continues to apply in the UK until the UK leaves the EU. However, how the UK legally leaves the EU is a more complicated question.
The Executive vs Parliament
There are significant questions over whether the Article 50 requirement for the UK to withdraw 'in accordance with its own constitutional requirements' means that the UK can give such notification using its prerogative powers, i.e. whether the Prime Minister can give the Article 50 notification without the approval of Parliament. This appears to be the stance adopted by David Cameron, who has said that the decision will be a matter for the new Prime Minister who, barring a snap general election, should be chosen by the Conservative Party by 9 September. A number of constitutional experts (and indeed, the House of Commons Library) appear to agree.
The alternative view is that Parliament must approve such notification, since the government cannot exercise the royal prerogative to remove legal rights given by Parliament. Would a Prime Minister be able to make an Article 50 notification against the wishes of Parliament? If the Prime Minister indicated a desire to do so, could Parliament hold a vote of no confidence in the government, the effect of which might be to remove the government's 'power' to make such a declaration?
A crowdfunding campaign has already begun in order to seek a declaration from the High Court on this issue. This begs certain questions. Would the courts accept that this is a question for judicial determination? A fundamental element of the principle of the rule of law is that it is for the courts to declare what the law is, including in relation to the constitution. At the same time, the courts' (sometimes varying) reluctance to become embroiled in overtly 'political' questions suggests that senior judges may wish to stay well away from becoming embroiled in this issue. However, it could be argued that this would be an abrogation of their constitutional function. If the High Court (and, inevitably, the Supreme Court) accepted jurisdiction and determined the issue, what would it mean for the UK's constitutional settlement, particularly if the court's decision was that Parliament should have the final say? In practical terms, where would such a declaration leave the relationship between the judiciary, Parliament, the government and the electorate?
If it does fall to Parliament to approve the Article 50 notification, either as a result of political consensus of judicial decision, what then? The system of representative rather than direct democracy means that referendums are rare, and MPs are elected to make decisions on behalf of their constituents. Since the referendum result was announced, many commentators have cited Edmund Burke's maxim that MPs must avoid being ‘bidders at an auction of popularity… Flatterers instead of legislators; the instruments, not the guides, of the people.’ In circumstances where roughly 75% of MPs declared (as at 22 June) they were not in favour of Brexit, while 52% of voters were in favour, what might happen? Could MPs refuse to accept the result of the referendum?
On one level, it would be extraordinary if Parliament ignored the result of the referendum. As the same Parliament passed legislation committing the country to a referendum, it could be said to be unconscionable for Parliament not to implement the result. Indeed, throughout the campaigning period, both sides argued that the result would be politically, if not legally, binding. Arguments about the behaviour and campaigns of both sides apart, Parliament and the Government asked the electorate for its opinion on Brexit, and the electorate responded.
Even so, with the immediate financial and social shocks of the referendum result being so severe, the electorate can perhaps sympathise with MPs for asking precisely what they would be being asked to approve, and whether in light of daily developments it would be sensible to continue to go down the path towards Brexit.
In one sense, this highlights the difficulty of putting such a complex issue to the electorate in the form of a binary question on whether or not the UK should remain a member of the EU, particularly on the basis of a single referendum decided by a simple majority. Members of the electorate voted for both Leave and Remain for very different reasons, and anticipated a range of different outcomes for the UK as a result of either decision. This has led to calls for a General Election in the near future so that the main political parties can seek a mandate from the country on the more nuanced question of what kind of Brexit the UK wants (or indeed, whether the electorate is suffering buyer's remorse and would rather forget the whole thing). Although single issue elections are uncommon, they are not unprecedented when rooted in an issue of constitutional importance (see for example the December 1910 General Election which led to the Parliament Act 1911, whereby the House of Lords lost its effective veto over legislation passed by the House of Commons).
Could we change the rules for the referendum?
A petition calling for a second referendum in the event of/on the basis of a majority of less than 60% and a turnout of less than 75% has amassed more than 4 million signatures. The petition was created on 23 May, before the referendum (ironically by a campaigner in favour of leaving the EU). However the vast majority of signatures were added after the referendum. This echoes similar provisions in the Scottish devolution referendum of 1979.
As the referendum is advisory, legally there is nothing to stop a second referendum being called. However, the EURA did not set any requirements for a second referendum or for a certain majority to be found before the result could be considered in any way decisive. As such, the first referendum cannot be considered 'void' in legal or constitutional terms, even if it is not actually binding. Parliament would have to legislate for a further referendum if it wished to put the question to the electorate again with added stipulations regarding majorities and turnout. It is not difficult to imagine the political crisis this may cause.
Can Scotland block Brexit?
As the First Minister has noted, despite an overall UK majority in favour of leaving the EU, 63% of the electorate in Scotland voted to remain. Nicola Sturgeon immediately stated that she would do everything possible to keep Scotland in the EU, including the possibility of a second independence referendum and even blocking Brexit for the entirety of the UK. Can the Scottish Parliament prevent Brexit?
The Scotland Act 1998 (as amended by the Scotland Act 2016, a result of the 2014 independence referendum), states that constitutional matters, including relations with the European Union, are a matter reserved to be considered by the Westminster Parliament. However, as a result of the 2016 amendments it also recognises the Sewel Convention, stating that '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 addition, it is notable that the Scottish Parliament's powers are limited by EU law.
Ultimately, there is a debate over whether membership of the EU can be said to be a 'devolved matter' or whether the Sewel convention as reflected in the Scotland Act could truly be the subject of a judicial decision. Moreover, most commentators agree that the current circumstances (whereby the majority of voters in a referendum have indicated their desire to leave the EU) are not 'normal' such that Westminster would not legislate in such a way which would affect the Scottish Parliament. However, questions remain, and even accepting that there may be no legal impediment in the devolution arrangements preventing a Brexit, there are clear reasons to suggest that a Brexit may ultimately lead to Scotland seeking a second referendum on independence.
Can we stay?
In that it is for the UK to give notification under Article 50, it remains open in theory for the UK simply not to give the notification. US Secretary of State John Kerry has suggested that the UK could beat a dignified retreat from the referendum result. The general tone from other EU leaders and the likes of Donald Tusk and Jean-Claude Juncker has not been positive, and in the event that the UK does somehow contrive a way to remain, the nature of its interaction with other EU members is likely to be frosty.
What happens if we leave?
In legal terms, EU law would no longer be supreme. Parliament would not be obliged to implement EU law or to follow the jurisprudence of the ECJ through the provisions of the ECA. Although this will be a welcome development to many, it perhaps ignores the extent to which the UK will want to retain a substantial amount of EU law, much of which the UK has been at the forefront of developing and promulgating. In addition, many matters covered by EU law are actually the result of separate international treaties, by which the UK would remain bound even if we leave the EU. The project of working through the array of EU law to determine what the UK wants (and may in some case be obliged) to keep will be a task taking several years. Beyond that, working out how to incorporate it once the ECA is repealed will be another gargantuan task. To try to do so via primary or secondary legislation would take up, on a conservative estimate, the lifetime of a five-year Parliament without room for any other kind of legislative programme. Trying to short-circuit this through the use of Henry VIII clauses (whereby an empowering statute allows secondary legislation to later primary legislation) and administrative rules made without the express approval of Parliament carries with it questions of legitimacy, particularly at a time when the use of Statutory Instruments is already under unprecedented scrutiny as a result of the Strathclyde Review.
The referendum result has left British politics and constitution up for grabs. The actions taken by the major parties, by MPs, and perhaps even by the courts in the coming weeks and months have the potential to shift the plates underlying how the UK is governed for generations to come. At this stage, there are very few definitive conclusions to be drawn, save to say that where we end up may be as much a case of what happens in practice, rather than how hard-edged questions of law are determined. From the perspective of lawyers who frequently grapple with issues of constitutional and administrative law, it is a fascinating process to see (although it would perhaps be more comfortable viewed from the outside). Even so, the sheer complexity of the issues and scale of the uncertainty around the arrangements fundamental to how we live and are governed mean that we could all be forgiven for cursing ourselves for living in such interesting times.
The residual discretionary powers historically enjoyed by the monarch, now exercised by the government rather than Parliament, and widely used in matters of foreign policy.
 Other countries using referendums in pursuit of significant constitutional change have taken a more stepped approach. For example, in new Zealand's 1993 referendum on changing its voting system, it held three referendums. The first referendum asked on an advisory basis whether voters wanted to retain First Past the Post ('FPP') or change system. The electorate wished to change. The second referendum asked which new voting system should replace FPP. The electorate chose a Mixed Member Proportional system. The third, binding referendum asked voters whether they chose FPP or MMP. The electorate chose MMP by a simple majority.