The ability of the constitution of the United Kingdom to respond to the ebb and flow of political and societal change has long been presented as a strength, and as one of the defining features of a system whose fundamental features have otherwise remained relatively stable. Significant renovation has occurred, but for the most part change has been incremental and, perhaps as important, relatively fragmented. Even the accelerated period of reform in the post-1997 period saw attempts to integrate change into the existing constitutional order and saw the rejection of proposals which were inconsistent with the UK’s constitutional traditions. Thus, as Jennings observed, the constitution has been ‘constantly added to, patched, and partially re-constructed, so that it has been renewed from century to century; but it has never been razed to the ground and rebuilt on new foundations’. The consequences of the referendum on EU membership may prove to be the undoing of this edifice.

Within days of the referendum, Mark Rutte, Prime Minister of the Netherlands, has noted the instability of established features of the United Kingdom, pre-emptively perhaps (but with the benefit of advocating a delay before initiating the terminal Article 50 process) commenting that ‘England (sic) has collapsed politically, monetarily, constitutionally and economically.’ One immediate consequence of the referendum has been to give rise to unprecedented uncertainty in our institutions of government. Our constitution, which might be expected to provide a framework in such circumstances, has shown itself to be worryingly deficient. Its legal dynamic is primarily reliant on a hitherto little-known (and never before used) article of the Lisbon Treaty; doubts exist over the nature of the power by which Brexit is actually triggered, the constitutional actor(s) who might be responsible for its initiation, whether the Article 50 process can be reversed, and over whether the process might never in fact begin (see here, here, here and here). Hopeful speculation has even attended to the possibility of a legal challenge to withdrawal from the EU (a sort of reverse ex parte Rees Mogg, with as little prospect of success).

The constitution’s political element meanwhile has revealed itself to be almost completely hollow, with one of the main political parties turning in on itself and the other facing an effectively directionless period in the transition between (pro-remain) leader and his (potentially Brexit-supporting) successor. The immediately-apparent absence of any clear plan as to what might actually happen following a vote in favour of Brexit – on the part of both sides of the campaign – is as damning an indictment as the speed with which the victorious side has distanced itself from many of the promises on which that vote was secured. JAG Griffith famously found the constitutional virtue in inactivity – ‘everything that happens is constitutional … if nothing happened that would be constitutional also’ – it is unclear that the political vacuum of the referendum’s immediate aftermath is what he had in mind.

A further product of this period of uncertainty has been speculation as to the knock-on effects upon the UK constitution of the vote to leave. The most pressing of these, with the different constituent elements of the UK displaying markedly different attitudes to the EU, is whether Brexit could precipitate the UK breaking apart. Nicola Sturgeon has already declared a new independence referendum ‘highly likely’ and bestrides Brussels like she is already a sitting head of government of an EU member state. And well she might. Far from being disheartened by the response that no deal can be done for Scotland whilst it remains part of the UK, she can use this response to generate the pressure for a speedy referendum, on the basis that if the Scots beat the Article 50 process the Scottish Government could claim to represent a continuing state and remain within the EU.

The independence timetable drawn up before the last referendum on Scottish independence suggested that independence would occur within 18 months of the result, and with current projections of a prolonged period of preparations before Article 50 TEU is triggered and a two year countdown from then, a window of opportunity is open to the Scottish National Party (SNP). Their problem, as with the 2014 referendum, is that without authorisation from Westminster the Scottish Parliament has no legal power to call a referendum. And whereas David Cameron saw the 2014 referendum as a means of heading off independence pressures, his successor may not be so accommodating. Sturgeon, however, has been assiduous in laying the groundwork for a renewed push. She can claim that she has a mandate to proceed in light of the SNP’s manifesto commitment to a referendum if the UK decides to leave the EU. Westminster resistance may only serve to bolster the SNP position.

In Northern Ireland, constitutional upheaval might unfold more gradually than it does in Scotland, but it is no less likely. The referendum casts a shadow over the DUP-Sinn Fein programme for government, and undermines the benefits of the corporation tax powers that Stormont fought so hard to gain. Whilst the Northern Ireland Assembly could still lower corporation tax to a level comparable to the Republic of Ireland doing so is now less likely to produce a major upsurge in inward investment whilst the uncertainty of the UK’s post-Brexit arrangements remains. In terms of the 1998 settlement, the North-South Ministerial Council is denuded of much of its workload as it will no longer be dealing with harmonising the transposition of EU law on both sides of the border. Moreover, visible symbols of the border, such as customs posts (necessary, dependent upon the shape of the Brexit negotiations, given that the border will be an access point into the European market) will become a lightning rod for dissident Republican sentiment.

Brexit also threatens to unleash a wave of isolationist sentiment that it is difficult for a new Conservative Party leader to resist. The Leave campaign made much of the claims by former head of MI6, Sir Richard Dearlove, that Brexit would reap security benefits for the UK. Those claims were based on Brexit enabling the UK to ‘dump the European Convention on Human Rights’. Theresa May launched her leadership bid by dampening down speculation that she would seek withdrawal from the ECHR, but only on the grounds that she accepted that such plans were not feasible in given the attitudes of MPs in the current Parliament. Other candidates will likely see the benefit in playing to the party base with prominent attacks on the ECHR and the Human Rights Act.

All of which could be rendered nugatory given the upheaval that Brexit has produced in the UK’s political order. Hannah Arendt once praised the UK’s two-party order for making it easy for the electorate to recognise authorship of particular policies and make judgments on performance. But Brexit cannot be “claimed” by the Conservatives or Labour and has exacerbated rifts in both parties. Just as the Liberal Party split over Home Rule in the 1880s, or the Labour/SDP split of the 1980s, the deep fissures within the parties threaten to tear them apart. But unlike those rifts the Fixed Term Parliaments Act 2011 opens up the possibility that rather than new political parties that are subjected to the test of public opinion, the leaders of the two main parties might be saddled with parliamentary factions that they cannot control. The Prime Minister cannot simply call a general election. For all the talk of a snap election, either a vote of no confidence is needed by a majority of MPs, with all the associated impact on a government’s credibility, or two-thirds of MPs need to back an election. Unless both of the main parties feel confident that they can gain from this scenario, at the other’s expense, there is little chance in an election before 2020 or of a prime minister cobbling together enough votes to repeal the 2011 Act.

In the face of such changes, Jennings’ metaphor is entirely apposite. As the constitution has been modified over time, what was once a new addition becomes embedded, and the foundation upon which further change is built. Given the cumulative extent of these potential changes, some thought ought also to be given to the process by which the decision to leave the EU was taken, the process which may – in turn – prove to precipitate rather more significant constitutional upheaval. The margin of victory for the leave campaign was that 51.9% of votes were cast in favour of exiting the EU to the 48.1% in favour of the United Kingdom’s continued membership (on a turnout of 71.8% of those eligible to vote). The winning differential was therefore a relatively narrow (or decisive, depending on your viewpoint) 3.8% of votes cast. The legitimacy of the referendum is itself a topic of debate, but it can be agreed that its outcome is both advisory (as a matter of constitutional law) and difficult for Parliament to reject (as a matter of constitutional practice). What can also be said is that if a referendum is a bald device for the gauging of popular opinion on an apparently isolated question, it looks even more so when the implications of the result are potentially so wide ranging as to be transformative of a constitutional order.

Consideration of the status of the decision reached by virtue of the referendum also hints that sovereignty – a term which is as misused as it is malleable but which still undoubtedly occupies a central place in the constitutional milieu – may also be under threat. The sloganeering of the Brexit camp offered the promise that the exercise of direct democracy via the referendum would ‘bring back control.’ What of that control – what of the will of the popular sovereign – in the event that the ‘all of the benefits, none of the costs’ model of integration with Europe turns out to be a pipe dream? What of the popular sovereign if – faced with an immovable EU looking to guard against further fractures – parliamentarians make concessions on free movement in order to secure access to the single market? In appealing to the sovereignty of the people on the basis of promises which may not in practice be deliverable the referendum holds the potential to expose a rift between direct and representative democracy. Should that rift widen – and in so doing undermine the notion of parliamentary sovereignty by diminishing its representative underpinnings – then Brexit may well turn out to be more damaging to the domestic constitutional order than the external influences of EU law may ever have been.

The resilience of this unwritten, flexible, responsive and cumulative constitution will undoubtedly be tested in the weeks, months and years to come. It remains to be seen whether, in the face of such structural trauma, it will be robust enough to survive.

Roger Masterman is a Professor of Law at Durham University.

Colin Murray is a Senior Lecturer in Law at Newcastle Law School.

(Suggested citation: R. Mastermind and C. Murray, ‘A House of Cards?’, U.K. Const. L. Blog (4th Jul 2016) (available at https://ukconstitutionallaw.org))