Politics in Northern Ireland has long been dominated by two alternative constitutional visions: remaining part of the United Kingdom, or unifying with Ireland. In this post – part of the Unit’s new and updated briefing series on key constitutional topics – Lisa James, Conor J. Kelly and Alan Renwick discuss Northern Ireland’s distinctive politics and political structures, and explain the UK government’s role in supporting long-term stability.

Background

Politics in Northern Ireland has long been dominated by the constitutional question – whether Northern Ireland should remain part of the UK, or instead unify with Ireland. In brief, unionists – historically associated with the Protestant community – have taken the first view, whilst nationalists – usually Catholic – have taken the second. Nationalists include ‘republicans’, while unionists include ‘loyalists’ – labels often associated with supporters or past supporters of paramilitary groups on each side. Those identifying as unionists were formerly in the majority, but that is no longer the case and a substantial number of people now identify with neither community.

Northern Ireland in its current form dates to 1921, when the Government of Ireland Act 1920 created the region from the six counties in north-east Ulster with the island’s largest Protestant communities, and also created the Parliament of Northern Ireland. The Anglo-Irish Treaty, which ended the Irish War of Independence and took effect in 1922, allowed Northern Ireland to choose between Irish unity or remaining a devolved part of the United Kingdom; the Northern Ireland Parliament chose the latter.

Following the outbreak of the violent conflict known as ‘the Troubles’ in the late 1960s, Northern Ireland’s political institutions ceased to function; direct rule (i.e. rule by Westminster) was instituted briefly in 1972, and again from 1974. A referendum on the constitutional question in 1973 was boycotted by nationalists, and failed to bring stability. Various attempts were made to end the Troubles and restore devolution, but all failed until the 1998 Belfast/Good Friday Agreement.

The Belfast/Good Friday Agreement

The Belfast/Good Friday Agreement was the result of sustained multi-party talks within Northern Ireland, in which many but not all political parties took part (with the Democratic Unionist Party dropping out in protest at Sinn Féin’s inclusion). The talks were chaired by US Senator George Mitchell, with the UK and Irish governments closely involved throughout, and Prime Minister Tony Blair and Taoiseach Bertie Ahern personally participating in the final stages.

The Agreement was endorsed in referendums held in Northern Ireland and Ireland on 22 May 1998. Voters in Northern Ireland backed the Agreement by 71.1% to 28.9%, on a turnout of 81%; support was cross-community, though much higher among nationalists. Those in Ireland voted by 94% (on a 56% turnout) to endorse the Agreement and the required constitutional changes.

The Agreement contained various measures designed to bring an end to ongoing violence, including prisoner releases and weapons decommissioning. It also sought to create the conditions and political structures necessary for long-term stability. The text clarifies that Northern Ireland’s constitutional position vis-à-vis the UK is based on consent, recognising both the legitimacy of the choice of the people of Northern Ireland, and the Irish right to self-determination. It also lays out the conditions under which that choice should be tested (discussed below). The Agreement commits the UK government to exercise power in Northern Ireland with ‘rigorous impartiality’ – i.e. favouring neither the unionist nor nationalist community – with the Irish government pledging to do the same if unification were to proceed. It requires the UK government to guarantee access to rights, courts and remedies under the European Convention on Human Rights (by incorporating it into Northern Ireland law); the Irish government likewise agreed to incorporate the Convention into Irish law.

The Agreement also provided for the creation of various democratic or coordinating institutions. Strand One established democratic structures for Northern Ireland – the Northern Ireland Assembly and Northern Ireland Executive – based on the principle of power-sharing. Strand Two of the Agreement created the North/South Ministerial Council, bringing together ministers from the Northern Ireland Executive and Irish government; Strand Three created institutions relating to East–West relations, with the British–Irish Intergovernmental Conference facilitating cooperation between London and Dublin; the British–Irish Council bringing together representatives from the UK, Ireland, Northern Ireland, Wales, Scotland, the Isle of Man and the Channel Islands; and the British–Irish Parliamentary Assembly convening parliamentarians from those same jurisdictions.  

How does power-sharing work in Northern Ireland?

Systems of power-sharing are designed to ensure that parties representing different communities have guaranteed political representation, and provide for cross-community decision-making.

All parties in the Northern Ireland Assembly must designate as unionist, nationalist or ‘other’. The largest party nominates the First Minister from among its Assembly members (MLAs); the largest party from the largest designation that does not include the First Minister’s party nominates the deputy First Minister. Despite their titles, the First Minister and deputy First Minister jointly lead the Northern Ireland Executive; they have equal powers, and hold office jointly, meaning that if one resigns, the other must also step down. The cabinet is multi-party; ministers are drawn from unionist, nationalist and ‘other’ groups in proportion to the number of seats each party holds in the legislature (with the d’Hondt method used to calculate allocations). Some decisions have to secure ‘cross-community support’ in the Assembly. Other matters may be made subject to the cross-community threshold via the ‘petition of concern’ mechanism, which can be triggered by 30 MLAs from two parties.

The joint appointment of the First Minister and deputy First Minister means that a single party can easily collapse or paralyse the institutions by refusing to nominate someone to either position, or through their representative resigning the position they hold. In this way, Northern Ireland’s political institutions have collapsed or ceased to function several times. In recent years:

• Sinn Féin collapsed the institutions in 2017, with the immediate catalyst being the Renewable Heat Incentive scandal. This left the region governed by the civil service alone, with budgets set by Westminster and political leadership absent. The institutions were restored in 2020.
• In 2022, the DUP collapsed the institutions in protest at the Brexit settlement for Northern Ireland (discussed below). As before, this left the region without political leadership until the institutions were restored in 2024. But even this restoration was controversial: some argued that the bilateral negotiation between the Conservative government and the DUP which led to it breached the UK government’s duty of rigorous impartiality.

The prominence of the constitutional question, and instability of political leadership, risk leaving social and economic policy topics neglected. The Belfast-based think tank Pivotal has identified major ongoing challenges in areas including public service delivery, economic policy, and infrastructure.

Brexit and Northern Ireland

Brexit posed particular challenges for Northern Ireland – which has the UK’s only land border with the EU. All UK and Irish governments have taken the view that the history of the region makes an open border critical, and the imposition of physical or non-physical trade or other barriers highly sensitive.

The potential impact of Brexit on Northern Ireland was largely ignored during the referendum campaign in Great Britain. Brexit also lacked a cross-community consensus within the region: the DUP backed Leave, with the other main parties supporting Remain. Northern Ireland as a whole voted by 56% to 44% in favour of Remain, but nationalists were overwhelmingly pro-Remain (88%) as were non-aligned voters (70%), whereas unionists were (less emphatically) pro-Leave (66%).

Post-Brexit arrangements for Northern Ireland – contained in the ‘Northern Ireland Protocol’, which was part of the UK–EU Withdrawal Agreement – were highly contentious both locally and at Westminster. Theresa May’s government set out three competing objectives: leaving the single market and customs union (allowing divergence from EU law); maintaining the UK’s territorial integrity (i.e. avoiding a ‘border down the Irish Sea’); and avoiding a hard border on the island of Ireland. These goals became known as the ‘trilemma’, on the basis that achieving any two ruled out the third.

The agreement negotiated by then Prime Minister Boris Johnson in late 2019 essentially sacrificed the second of these goals. It allowed Great Britain to diverge from EU law while avoiding a hard border, but required that goods moving from Great Britain to Northern Ireland should comply with relevant rules of the EU customs union and single market. This decision was opposed by unionists. In the following years, Conservative governments twice proposed to legislate in breach of the UK’s Withdrawal Agreement obligations – though both sets of provisions were ultimately dropped.

The Windsor Framework, agreed in 2024, introduced changes to streamline the customs process. These included a ‘green lane’ system for goods moving from Great Britain to Northern Ireland, but not from Northern Ireland into the EU, and simplified some checks on agri-food products. The Windsor Framework also introduced the Stormont Brake: a mechanism allowing MLAs to object to applying an updated EU law to Northern Ireland, subject to various substantive and procedural requirements adjudicated by the Secretary of State for Northern Ireland.

Throughout this period, the UK government was accused of failing to properly consider the needs of the region and the importance of stability in Northern Ireland. This strained relationships between the UK and Irish governments, and between the UK government and communities in Northern Ireland.

The future of Northern Ireland

The Belfast/Good Friday Agreement allows for two constitutional futures for Northern Ireland: within the UK, or as part of a united Ireland. Polling suggests that a clear majority still favours the former option, though support for change has grown in recent years.

So long as Northern Ireland remains part of the United Kingdom, a key question will be how it can best be governed. Various changes have been proposed to strengthen the institutions. An inquiry by the House of Commons Northern Ireland Affairs Committee recommended reforms to the appointment processes for the First and deputy First Ministers, and the Speaker of the Northern Ireland Assembly. A Constitution Unit report analysed potential changes to executive formation, other aspects of the Executive, the Assembly, and other institutions. A Northern Ireland Assembly committee is considering the options for Assembly and Executive reform. But any proposed changes would need cross-community support and, while there is a degree of consensus about some of the challenges facing the institutions, there is little agreement on what changes would be desirable.

For unification to take place, consent must be given in both Northern Ireland and Ireland. The Secretary of State for Northern Ireland must call a ‘border poll’ if it ‘appears likely’ to them that a majority in Northern Ireland would vote for unification. But many key matters are not resolved by the Agreement, including:

• how the likelihood of a majority should be measured (for example through election results, polling evidence, or a combination of both)
• how a referendum would be designed (e.g., question wording, franchise, campaign rules)
• how and when proposals for the form of a united Ireland would be developed.

A Constitution Unit project explored options relating to these questions. It emphasised that any such process should seek to safeguard stability in Northern Ireland and Ireland, prioritise procedural legitimacy, and offer voters a clear and informed choice, made through an inclusive process.

What is the UK government’s role?

The Labour government came to power in 2024 pledging to restore ‘stability and long-term certainty’ in Northern Ireland. This included a promise to repeal and replace controversial 2023 legislation on the legacy of the Troubles, which had been opposed by major Northern Ireland parties from all communities as well as by victims’ groups, human rights organisations, and the Irish government. This pledge has been partly fulfilled, and a framework for further change set out.

Relationships between Belfast and London, and between Dublin and London, have been damaged in recent years. But trust is needed for Northern Ireland’s institutions and society to function well. This requires UK politicians to be aware not only of the unique features of Northern Ireland politics, but also of the critical importance of relationships across Northern Ireland’s communities, and with its key international partners, most notably Ireland. Finally, long-term stability will require the UK government to uphold the Belfast/Good Friday Agreement’s principle of rigorous impartiality in its approach.

This briefing is part of a series designed to inform policy-makers and the public about key constitutional issues and democratic debates. It is an output from the Constitutional Principles and the Health of Democracy project. Every briefing is available to read on the Constitution Unit’s website, in both webpage and PDF format.

About the authors

Lisa James is a Senior Research Fellow at the Constitution Unit.

Conor J. Kelly is the Bingham Fellow in Constitutional Studies at Balliol College, University of Oxford and an Honorary Research Associate at the Constitution Unit.

Alan Renwick is Professor of Democratic Politics at UCL and Deputy Director of the Constitution Unit.

Image attribution: ‘UK Government hosts UK Investment Summit at Guildhall‘ by UK Government/Alecsandra Dragoi /No 10 Downing Street (CC BY-NC-ND 2.0).