The Good Friday/Belfast Agreement had to address a fissure in constitutional thought on the island of Ireland; was the legitimacy of the island’s constitutional arrangements dependent upon one group of constituent power holders, or two? The question had been contested since partition, and this contribution explores how the conundrum was tackled through John Hume’s concept of a people of Northern Ireland, who would have the ability to determine whether to remain within the UK or join a unified Ireland. This concept might have sufficed during the 1998 negotiations, but it remained all-but-unexplored in the years after, until the aftermath of the June 2016 Brexit referendum. Brexit changed the debate on the (re)unification of Ireland, and this contribution examines three facets of this shift. First, it necessitates a new understanding of this group of constituent power holders. Second, to reflect the 1998 Agreement, the people of Northern Ireland also gained special protections in the UK-EU Withdrawal Agreement. Third, alongside these developments, the UK Government’s application of immigration rules and ascription of nationality to the people of Northern Ireland called the nature of this status into question. This article considers how these factors are shaping contemporary debate over Northern Ireland’s constitutional future.

Brexit imposed a new binary on Northern Ireland politics which has interacted with the national question in complex ways. This interaction is the focus of this chapter. It begins by reviewing the position of the five main Northern Ireland parties on Europe prior to 2016. It explains the parties’ stances during the Brexit referendum campaign and examines how the parties responded to the referendum result. The chapter argues that Brexit produced constitutional restlessness in Northern Ireland because the vote lacked legitimacy according to the standards of consent contained in the 1998 Good Friday/Belfast Agreement. The chapter then traces how the new constitutional debate became established, highlighting how, although the debate was initiated by Brexit, it was intensified by subsequent developments in British and Irish politics. The chapter also explores key dilemmas that the debate posed for the political parties. The conclusion suggests that constitutional deliberations look set to continue but possibly at a lower intensity. Their direction will be shaped by developments in 2019-20 including the Boris Johnson Brexit agreement, the new Irish government, the restoration of devolution in Northern Ireland, and the coronavirus crisis.