From an international and constitutional law perspective, the fallout from the Brexit vote has been and continues to be dramatic. Pursuing such radical change necessarily raises questions about the legitimacy of the process of disengagement, and about whose voices will be heard and considered in the ensuing debate about political reordering. Both the European Union and its member states gain strength and vulnerability from their constituent communities, and the United Kingdom is certainly no exception.

This paper examines the recent United Kingdom Supreme Court Miller decision on the invocation of article 50 of the Treaty on European Union, as well as the reasoning of the Supreme Court of Canada in the Reference re Quebec Secession to see what guidance might be found regarding the subtle complexity of both sustaining and reforming a constitutional democracy. This analysis suggests that there are difficult lessons to learn from Brexit about constitutional fundamentals, constitutional complexity and the interconnection between international and constitutional aspirations. It would seem that the legitimacy of withdrawal from the European Union will in some measure be judged by how well the leaders heed the voices of constituent communities and work to accommodate them in the new international and constitutional ordering.

Brexit: The International Legal Implications is a series examining the political, economic, social and legal storm that was unleashed by the United Kingdom’s June 2016 referendum and the government’s response to it. After decades of strengthening European integration and independence, the giving of notice under article 50 of the Treaty on European Union forces the UK government and the European Union to address the complex challenge of unravelling the many threads that bind them, and to chart a new course of separation and autonomy. Brexit necessitates a deep understanding of its international law implications on both sides of the English Channel, in order to chart the stormy seas of negotiating and advancing beyond separation. The paper series features international law practitioners and academics from the United Kingdom, Canada, the United States and Europe, explaining the challenges that need to be addressed in the diverse fields of trade, financial services, insolvency, intellectual property, environment and human rights.