Ahead of the launch event for their new book on the continuing constitutional pressures of Brexit, Oran Doyle, Aileen McHarg and Jo Murkens summarise the book’s introductory essay. They conclude that, five years on from the seismic constitutional event that was the 2016 referendum, it is clear that Brexit is exerting pressure on various aspects of the constitution, but it remains too early to tell the full impact of Brexit on the UK constitution.

The United Kingdom’s withdrawal from the European Union was clearly a development of major significance that affected the UK constitution and its three legal systems, and brought about a series of political crises. But the prolonged process of negotiating the terms of withdrawal and the future UK-EU relationship also imposed and exposed a range of other constitutional tensions and pressures. This is true not only in respect of the UK itself, but also for the EU – which experienced a major recasting of its external borders, a recalibration of internal decision-making dynamics, and challenges to core features of its constitutional order – and in particular for Ireland – which, by virtue of its geographic position and constitutional history, has faced unique political and constitutional challenges as a consequence of Brexit.

In The Brexit Challenge for Ireland and the United Kingdom: Constitutions Under Pressure, recently published by Cambridge University Press, scholars based in the UK and Ireland explore a wide range of constitutional, legal, and political issues affecting both countries which have arisen out of Brexit. These include questions of territorial governance within the UK, the renewed prospect and implications of a united Ireland, the use of constitutional referendums, the impact of Brexit on political parties, executive-parliamentary relations, and the role of the courts and law officers in constitutional disputes.

In the editors’ introductory essay, we trace these constitutional difficulties to four deeper sets of tensions. The first is an uneasy relationship between the UK and the EU – predating and now post-dating the period of the UK’s membership. The second is the complex and contested nature of the UK’s own territorial constitution, with long-standing tensions between an over-arching British national identity supposedly threatened by EU membership, and more fluid – and fractured – sub-state identities, both significantly complicating the politics of Brexit and in turn exacerbated by the handling of the Brexit process. The third is an uneasy relationship between the UK and Ireland, whereby the incomplete rupture of Ireland from the UK in 1922, in particular the partition of the island of Ireland, left a legacy of divided loyalties and contested territorial claims. The recognition of shared UK and Irish interests in the governance of Northern Ireland contained in the 1998 Belfast/Good Friday Agreement inevitably meant that Ireland had a particular interest in the outcome of Brexit, while Brexit destabilised the foundations upon which that settlement had been reached. Finally, we identify deep tensions within the UK’s constitution itself, in particular arising from the attempt to undo the constitutional effects of EU membership in a constitutional order which has undergone profound, yet incomplete, change partly as a consequence of that membership.

While the Brexit process formally came to an end on 31 December 2020, when the implementation period expired, and EU law ceased to have effect in the UK, the constitutional pressures created by Brexit continue to be felt.

The negotiation of the Withdrawal Agreement and the Trade and Cooperation Agreement have not settled the uneasy relationship between the UK and the EU. The agreement allows for tariff-free and quota-free market access for goods, but not services, provides for specific areas of cooperation, and has released the UK from its obligation to comply with EU policies on trade and immigration (‘free movement’ rules). The Ireland/Northern Ireland Protocol to the Withdrawal Agreement – hastily agreed by the Johnson government as the price of ‘getting Brexit done’ – has proved to be a source of considerable ongoing problems. Under the Protocol, Northern Ireland continues to follow some European Single Market rules, e.g. in relation to product standards. Goods of animal origin need to be checked at Northern Ireland ports when they are transported from Great Britain. The Protocol is strongly resented by Northern Ireland’s unionist parties in particular for placing this form of border in the Irish Sea. The UK government has encouraged and adopted the concerns of the unionist parties. However, by seeking a complete rewrite of the Protocol, by threatening to suspend it if necessary, and by fending off infringement proceedings by the EU against the UK, the UK government is creating a perception that it is not a trustworthy partner.

Internal territorial tensions also continue post-Brexit, which has not only had a technical impact on the nature of devolved competences (via the EU (Withdrawal) Act 2018, the United Kingdom Internal Market Act 2020 and other legislation), but has altered the balance of the territorial constitution. After two decades of increasing territorial autonomy, we are seeing a reversion to a much more unitary understanding of the constitution, and of the place of devolution – and territorial divergence more broadly – within it. This is producing reactions in all four parts of the UK. In Northern Ireland, unionist politicians have sought, unsuccessfully, to challenge the Northern Ireland Protocol on the ground that it breaches the 1800 Acts of Union. Amidst rising political tensions, DUP ministers in the Northern Ireland Executive are also refusing to participate in North-South Ministerial meetings under the Belfast/Good Friday Agreement. In Wales, the Welsh government has an ongoing challenge to the United Kingdom Internal Market Act 2020, arguing that it should not be read as amending the devolution statutes. It is also establishing an independent commission on the constitutional future of Wales, which will consider independence as a possible option. In Scotland, the Scottish government continues to insist that it has a mandate – and that Brexit provides the justification – to hold a second independence referendum, and that it intends to hold one during the lifetime of the parliament elected earlier this year. Meanwhile, the sole concession to England’s distinct constitutional identity – the English Votes for English Laws procedure in the House of Commons – was abolished in July without so much as a vote.

The future of the Northern Ireland Protocol remains shrouded in uncertainty. Its full impact on trade is difficult to assess in the context of the COVID-19 pandemic and because it has not been fully implemented. Post-Brexit checks on certain goods entering Northern Ireland, e.g. the ban on chilled meats also known as the ‘sausage wars’, have been suspended and ‘grace periods’ have been extended indefinitely. Moreover, the UK has, with respect to trade with the EU, delayed imposing new border checks to mitigate the ongoing supply chain issues. Notwithstanding uncertainties around the details, the Protocol casts the spotlight on Northern Ireland, where border issues dominate discussion of constitutional futures. Irish (re-)unification continues to be actively discussed; an issue that has broader implications for Ireland’s constitutional order than simply the expansion of its territory.

Finally, the constitutional fallout from the Brexit process continues to be felt more generally within the UK constitution. The UK government is proving itself willing to exploit the power of its parliamentary majority to roll back a range of recent constitutional reforms, and to reduce checks on executive power – both parliamentary and judicial – that it says hampered its ability to ‘get Brexit done’. So far, attempts to curb judicial power have been relatively minimal. However, with a review of the Human Rights Act still to report and a review of the Constitutional Reform Act apparently in the offing, more substantial reforms could still be to come.

Thus, when constitutional historians come to assess the impact of Brexit, they are unlikely to see it as discrete event, or one solely concerned with the UK’s trading relationships with its European neighbours. However, more than five years on from the seismic Brexit referendum, it is still much too early to tell just how widespread, and how significant its impacts will be.

A launch webinar for the authors’ book, The Brexit Challenge for Ireland and the United Kingdom: Constitutions Under Pressure, will take place on 10 November at 7pm. Tickets are still available as of the date of publication.

About the authors

Oran Doyle is Professor in Law at Trinity College Dublin.

Aileen McHarg is Professor of Public Law and Human Rights at Durham University.

Jo Murkens is Associate Professor of Law at the London School of Economics and Political Science.

All three served as co-editors of The Brexit Challenge for Ireland and the United Kingdom: Constitutions Under Pressure.