Following the 2016 UK referendum, Brexit emerged as one of the most symbolic cases of “reverse integration” in the twenty-first-century process of European integration, attracting sustained attention not only across Europe but also within the broa...
Following the 2016 UK referendum, Brexit emerged as one of the most symbolic cases of “reverse integration” in the twenty-first-century process of European integration, attracting sustained attention not only across Europe but also within the broader international community. As the first instance of a member state withdrawing from the European Union, Brexit has brought about profound transformations in the United Kingdom’s political, economic, and social structures, while simultaneously generating complex ripple effects on the EU’s institutional stability, intra-member power relations, and the geopolitical order of Europe. In particular, issues related to security, trade, border management, and regional identity have become increasingly salient in the post-Brexit context.
During the Brexit process, the Northern Ireland issue once again moved to the center of political debate. As part of the United Kingdom, Northern Ireland shares a land border with the Republic of Ireland, which remained in the European Union after Brexit and continues to use the euro as its official currency. Consequently, Ireland became the only EU member state to share a land border with the UK following Brexit. This unique geopolitical and institutional configuration rendered the Northern Ireland border a core issue in negotiations between the UK and the EU. In particular, the challenge of avoiding a “hard border” while maintaining the integrity of the Single Market and the customs regime posed a direct threat to the peace settlement established under the 1998 Belfast Agreement.
This thesis applies a comprehensive theoretical framework drawing on European integration theory, neofunctionalism, intergovernmentalism, and regionalism to analyze Brexit as a paradigmatic case of reverse integration, and to examine the resulting changes in EU institutional governance and the reconfiguration of regional governance structures. Furthermore, by employing theories of national identity and institutional choice, the study systematically explores post-Brexit transformations in political identity in Northern Ireland, shifts in institutional preferences, and the resurgence of debates surrounding independence and Irish reunification.
Methodologically, this study adopts a qualitative research approach, combining literature review, policy document analysis, and case studies. It examines EU official documents, UK government white papers, policy materials related to Ireland and Northern Ireland, and major academic studies. In addition, by analyzing the institutional design and implementation outcomes of the Northern Ireland Protocol and its subsequent corrective arrangement, the Windsor Framework, this research evaluates both their effectiveness and limitations.
The findings indicate that Brexit has weakened the long-standing assumption of the irreversibility of European integration, while simultaneously highlighting the growing importance of border management and regional stability at the EU level. In the case of Northern Ireland, the newly established post-withdrawal trade and economic regime has exerted gradual yet significant influence not only on the regional economic structure but also on residents’ perceptions of identity and political choices. The increasing frequency of opinion polls on Irish reunification suggests that Northern Ireland’s future remains highly uncertain.
In conclusion, this study interprets Brexit not merely as an episode of national withdrawal, but as a structural challenge to European regional governance and prevailing conceptions of sovereignty. The Northern Ireland issue represents a prominent external manifestation of these transformations, and its future trajectory will be shaped by UK–Ireland bilateral relations, the EU’s strategic adjustments, and evolving public opinion within local communities. Through an in-depth analysis of these dynamics, this research aims to contribute both academic and policy-relevant insights to the ongoing debate.