Institutional Divergence and Policy Evolution in Post-Brexit United Kingdom and Northern Ireland: Exploring the New Institutionalism Perspective

This study explores institutional divergence and policy evolution in the post-Brexit United Kingdom, with a focus on Northern Ireland’s distinctive governance. It analyzes how Brexit reshaped regulatory alignment, trade policy, and intergovernmental coordination, emphasizing the consequences of divergence between Northern Ireland and Great Britain for policy coherence. Grounded in New Institutionalism, the research highlights the influence of institutions, regulations, practices, and historical legacies on governance outcomes. Using a comparative qualitative design, documentary evidence was drawn from legal texts, parliamentary proceedings, policy reports, and scholarly literature. Findings show that Brexit placed Northern Ireland in a unique regulatory position through the Protocol on Ireland/Northern Ireland and the Windsor Framework, introducing mechanisms such as green- and red-lane trade arrangements, democratic consent procedures, regulatory harmonization, and revisions to EU-derived legislation. These changes have generated regulatory fragmentation, political contention, trade sensitivities, and greater complexity in multi-level governance. The study recommends closer UK–EU–Northern Ireland collaboration, transparent management of Northern Ireland’s special status, improved intergovernmental consultation, flexible regulatory coordination, and inclusive policy negotiation to reduce uncertainty and support coherent governance in the post-Brexit era.