UCL Faculty of Laws


Shaping the legal framework for Brexit

This case study is part of the 2021 REF submission in which UCL Laws was assessed as No.1 for research excellence in the UK.


Since joining UCL, Professor Eeckhout, Professor King and Professor Hickman have undertaken research into EU and UK constitutional law, and the relationship between the two. With the prospect of Brexit, this research was developed further to address the urgent and novel legal questions raised by the 2016 Brexit referendum outcome and, in particular, to clarify the process by which the UK could notify the EU of its intention to withdraw from the EU (King and Hickman), and the revocability of that notification (Eeckhout).


UCL Laws contributed directly to shaping the legal framework for Brexit, triggering action leading to litigation, supporting legal advocacy, and informing landmark UK and EU judicial decision-making on fundamental constitutional norms at the heart of the Brexit process: 

  1. Research by Hickman and King (with Hickman part of Gina Miller’s legal team) developed arguments that prevailed in the landmark Miller I decision (Supreme Court, 2017), which established a critical UK constitutional requirement for Brexit: that the executive could not initiate withdrawal from the EU without an Act of Parliament.
  2. Research by Eeckhout (later joining the Wightman litigation team) developed a ‘constitutionalist’ reading of Article 50 TEU on which the Advocate-General and CJEU relied in the Wightman case (CJEU, 2018), establishing that a notification of EU withdrawal, once made, could later be unilaterally revoked by the UK. 

These decisions strengthened the role of the UK Parliament, developed key EU constitutional norms, and clarified the legal and political possibilities that remained open as the UK approached Brexit.

References to the research

Tom Hickman, ‘Revisiting Entick v Carrington: Seditious Libel and State Security in Eighteenth Century England’ in A Tomkins and P Scott (eds.), Entick v Carrington: 250 Years of the Rule of Law (Hart 2015), pp. 43–84.
Jeff King, Judging Social Rights (Cambridge University Press 2012).

Nick Barber, Tom Hickman and Jeff King, ‘Pulling the Article 50 “Trigger”: Parliament’s Indispensable Role’, UK Constitutional Law Blog (27 June 2016), https://ukconstitutionallaw.org/2016/06/27/nick-barber-tom-hickman-and-j....

Piet Eeckhout and Eleni Frantziou, ‘Brexit and Article 50 TEU: A Constitutionalist Reading’ (2017) 54 Common Market Law Review 695–733.