The United Kingdom’s constitution and Brexit: A ‘constitutional moment’?

I recently completed work on an article for a special issue of the Japanese legal journal Horitsu Jiho. The theme of the special issue is the impact of the forces of globalisation and nationalism on constitutional law and the study of it. In my contribution, I consider the potential implications of the United Kingdom’s departure from the European Union for the future of UK constitutional law. In particular, I consider the extent to which Brexit might legitimately be considered to amount to a ‘constitutional moment’ in the sense of an event that might justifiably come to be regarded as a significant inflection point in the UK’s constitutional history.

I begin the piece by noting that the United Kingdom’s constitution is, by any reasonable standard, an unusual one. The reason for this, it is sometimes said, is that the UK’s constitution is an evolutive one that has developed incrementally over a long period of time, rather than being the product of the sort of a defining ‘constitutional moment’ that, in many countries, supplies the supplies the foundation upon which (new) constitutional arrangements are built. Yet while there is certainly something to this narrative, it is not without difficulty. For one thing, the UK undoubtedly experienced a highly significant constitutional moment in the late 17th century, when the fundamental principle was established that the Crown in Parliament enjoys legislative supremacy, thus giving rise to the axiomatic concept of parliamentary sovereignty. However, while these events, which reached their denouement in 1688-9, doubtless amounted to a constitutional moment, what is unusual — and what sets the UK constitution apart from nearly all others — is that that critical moment was not followed by any recognisable form of codification. In this way, the near-uniqueness of the UK’s constitutional arrangements is attributable not to the want of any significant constitutional moment in the UK’s long constitutional history, but to the absence of any attempt to codify the implications of such a moment. That lack of codification certainly does not, however, detract from the defining significance of what happened in the late 1600s, whereby parliamentary authority was established at the expense of monarchical power.

More than 300 years later, the question arises whether the UK is currently experiencing another constitutional moment which, questions of codification aside, might prove to be as significant an inflection point in the UK’s constitutional history as the events that unfolded in the 1680s. The occasion for asking that question is provided by the UK’s departure from the European Union, which occurred on 31 January 2020. This is so for two reasons. First, withdrawal from the EU was a highly significant constitutional — and well as social, economic and political — development, the repercussions of which will be felt for a very long time to come. Second, however, Brexit is the antithesis of a self-contained phenomenon in constitutional — as in other — terms. As well as being a consequential constitutional event in its own right, Brexit is likely to yield, and in some respects is already producing, substantial reverberations within the wider constitutional order. Against this background, the purpose of my article is to sketch the existing and likely constitutional implications of Brexit for the UK and, in doing so, to assess whether the UK is currently experiencing what history might come to regard as a ‘constitutional moment’ that will, in decades to come, be regarded as a significant milestone in the development of the UK’s constitutional arrangements.

My article is published in Japanese in Horitsu Jiho. A version of the piece in English can be downloaded via SSRN.