Northern Ireland and the United Kingdom internal market: the exception that disproves the rules?

Post-Brexit Northern Ireland (NI) occupies a unique position in the internal market of the United Kingdom (UK) due, primarily, to the Protocol on Ireland/NI, or Windsor Framework. Agreed as part of the UK–European Union (EU) Withdrawal Agreement, the Protocol/Windsor Framework provides that EU single market rules concerning the free movement of goods, customs, value-added tax, state aid and energy markets continue to apply in NI, despite it having formally left the EU along with the rest of the UK. To allow for the domestic implementation of the novel arrangements for post-Brexit NI, set out in the Protocol/Windsor Framework, the UK Internal Market Act 2020 (UKIMA) includes a series of specific provisions that except goods entering and leaving NI from the ‘market access principles’ established by UKIMA in certain circumstances.
This commentary first introduces UKIMA and then presents a review of its provisions that are specifically dedicated to post-Brexit NI. Concluded in March 2024, the analysis then provides an assessment of the implications of measures agreed between the UK and EU and laid down in the Windsor Framework texts published in February 2023, it also briefly considers the implications of the subsequent Safeguarding the Union deal between the Democratic Unionist Party and UK Government, finalised in January 2024.
Based on the analysis of UKIMA set against the backdrop of the Protocol, then Windsor Framework, then Safeguarding the Union, the commentary argues that the position of NI post-Brexit is not only newly unique but also newly consequential for those both inside and outside its borders.
Keywords: United Kingdom internal market; Northern Ireland; Protocol on Ireland/Northern Ireland; European Union; Windsor Framework; regulatory alignment and divergence.