In February 2022, the Democratic Unionist Party withdrew the First Minister of Northern Ireland’s executive, effectively collapsing the region’s power sharing institutions. Shortly before, the DUP’s Minister of Agriculture ordered his department to stop all checks on goods moving between Great Britain and Northern Ireland. The DUP’s unilateral actions, despite having campaigned in favor of the departure in a 2016 referendum, reflected unionist concerns with the consequences of the UK’s withdrawal from the European Union.

The source of unionist protest was a portion of the UK withdrawal agreement relating to trade called the Ireland/ Northern Ireland Protocol. The provision left Northern Ireland de jure in the European Single Market for goods and agriculture, and de facto in the EU Customs  Union , meaning that goods moving between Great Britain and Northern Ireland would be checked at what unionists framed as an “Irish sea border” and businesses would be responsible for ensuring compliance with both EU and UK regulations. The DUP argued that the Protocol created a “democratic deficit,” and cited uncertainty for businesses among their justifications for their withdrawal from the executive.

My research sought to explain questions regarding the DUP’s high-risk decision making. I conducted interviews with members of the UK government and negotiating teams in London, Brexit negotiators from the EU in Brussels, and officials from the Northern Ireland Assembly across the region. Over fifteen interviews allowed me to connect face to face with the people driving the DUP’s decision making as well as those most affected by its actions. I also built a database of public commentary on the Northern Ireland Protocol to track changes in different parties’ stances on the agreement over time.

Three hypotheses emerged over the course of the interviews. Firstly, that DUP national and devolved representatives were divided in their decision to withdraw from power sharing and on their initial support to vote “leave the EU” in the Brexit referendum. The second was that the DUP took a deliberately populist stance on Brexit and Protocol issues to secure votes which were in danger of being lost to more extreme unionist parties. This theory seemed more probable in 2022 by which time Sinn Fein, a nationalist party, overtook the DUP as the largest party in the Northern Ireland Assembly, prompting unionist concerns about a looming referendum on Irish Reunification. This response to constitutional issues provides a third explanation for the DUP’s perplexing behavior.

The decisiveness of the DUP’s actions belies significant divisions within the party as they are faced with newly urgent threats to the future of unionism. The hypothesis that the DUP is fighting against significant internal dissent has grown more salient as recent polling data suggest that the DUP overtakes other unionist parties in vote share, solidifying its place as the second largest party in the region. If the DUP continue to refuse to enter government, they may also bring into question the future of Northern Ireland’s power sharing institutions which many argue are no longer fit to represent a majority of its citizens.