This paper explains the legal and political background to the three extensions of the UK’s EU-exit process under Article 50 of the Treaty on European Union (TEU). It sets out the UK Parliament’s role in the seeking and agreeing to those extension decisions of the European Council.Jump to full report >>
When a Member State seeks to leave the EU, a process is initiated under Article 50 TEU. Once a Member State has decided to withdraw, and then notified the European Council of its intention, the process formally begins. At first instance, the departing Member State and the EU have up to two-years (from the point of notification) to conclude a withdrawal agreement. The EU Treaties then cease to apply:
The UK notified the European Council of its intention to leave the EU on 29 March 2019.
Since then, three extension decisions have been taken by the European Council (on all three occasions with the agreement of the UK Government). The first two of these decisions were taken while Theresa May was the UK Prime Minister.
On 19 October 2019 the current Prime Minister, Boris Johnson, sent a letter to the President of the European Council requesting an extension of Article 50 until 31 January 2020. He did so despite publicly opposing an extension beyond 31 October 2019.
The Prime Minister had no choice but to send this letter because it was required by an Act of Parliament, the European Union (Withdrawal) (No. 2) Act 2019. The Act stated that the Prime Minister had to send the letter if, by 19 October 2019 the Government had not secured a resolution of the Commons either approving:
On 28 October 2019, the European Council announced that it had decided to offer the 3-month extension set out in the letter. The Prime Minister, though describing the extension in a letter to Donald Tusk as an “unwanted prolongation of the UK’s membership of the EU” nevertheless accepted this offer. He was required to do by section 3 of the EU (Withdrawal) (No. 2) Act 2019.
This means that, unless the Withdrawal Agreement is ratified and enters into force at the end of either November or December, the UK will leave the European Union no earlier than 31 January 2020.
It may also be helpful to refer to the following other Commons Library Briefing papers, which covered the first two extensions of Article 50:
and to the Commons Library Insight concerned with the most recent extension:
 Also known as “the Benn Act” as it was introduced as a Private member’s bill by Hilary Benn MP.
Commons Briefing papers CBP-8725
Author: Graeme Cowie