There is no domestic legal or constitutional requirement for a vote to be held in Parliament to approve the Withdrawal Agreement before it is concluded by the UK and the EU under Article 50 of the Treaty on the European Union (TEU).
This is from the May 2018 research briefing from the House of Commons Library on the role of parliament in the European Union (Withdrawal) Bill.
The report argues that the Government can negotiate and sign an international treaty using its prerogative powers and without any formal parliamentary involvement.
The report finds:
- On 17 January 2017, the Prime Minister announced in her Lancaster House speech that the Government would put “the final deal that is agreed between the UK and the EU to a vote in both Houses of Parliament, before it comes into force”
- On 13 July 2017, the Government introduced the European Union (Withdrawal) Bill 2017-19 to the House of Commons. As introduced, the Bill contained a power to make secondary legislation to implement the Withdrawal Agreement
- On 13 December 2017, David Davis published a written statement which set out some of the details relating to the proposed votes on the Article 50 agreements
- On 25 April 2018, in evidence to the Commons Exiting the European Union Committee, David Davis was asked about the length of time between the publication of the final agreements and the vote in Parliament, and he confirmed that the UK Parliament’s vote would take place before the European Parliament’s vote
- On 28 February 2018, the European Commission published a draft of the Withdrawal Agreement text. The EU published an amended draft text on 15 March and another draft on 19 March which contained areas of agreement between the EU and the UK
- Negotiations will continue in the coming months, with a view to agreeing a final draft in October 2018. The final text of the Withdrawal Agreement is not expected to be published until the negotiations are formally concluded.