Chatham House Primer: Brexit

At a Chatham House event on 18 July, Professor Sionaidh Douglas-Scott, a European constitutional law expert, outlined the legal requirements needed for the UK to leave the EU (Brexit).

She started out by contrasting the UK’s situation with other EU countries when it comes to referenda. She stressed that referenda have not been a major part of the UK’s constitution, which means British people are often unaware of the constraints and of the laws that surround a referendum. She added that other EU countries have particular constraints on how referenda may be held (they might impose voting thresholds, requirements for more than a simple majority,…)

hand-holding-brexit-sign-eu-referendumShe went on to speak about article 50 which states “any member state may decide to withdraw from the Union in accordance with its own constitutional requirements.” She added that the UK is not very clear about what its constitutional requirements are.


In her opinion, there are therefore four possibilities:

  • Notification under the constitution is a matter for the Prime Minister;
  • Constitutional conventions: Parliament has to have a say and convention dictates that Parliament should have a vote;
  • It is not enough for the Prime Minister to go to Brussels and say the UK wants to withdraw. There has to be another act of Parliament first;
  • Neither is it enough to notify Brussels without the consent of the devolved nations.

Professor Douglas-Scott also covered what happens once Article 50 is triggered: the withdrawal agreement and future trade agreements. She spoke about different types of relationship the UK could have with the EU and concluded that only two options were feasible in her view: joining the European Economic Area or signing an ad-hoc agreement, based on WTO rules.

Watch the speech here

The Chatham House Primer Series is a unique programme of talks designed to bridge the gap between introductory level subject knowledge and a more advanced understanding geared towards practical application, higher-level discussion and policy debate.

With each talk hosted by a leading expert, the Primer series aims to provide the audience with a solid grounding in topics of academic curiosity, key international affairs concepts and the issues behind the news.