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). The Government can negotiate and sign an international treaty using its prerogative powers and without any formal parliamentary involvement. Article 50 TEU requires the consent of the European Parliament for the Withdrawal Agreement to be approved.Jump to full report >>
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”. The Government also confirmed that the votes in Parliament would be held before the European Parliament votes on the Withdrawal Agreement under the terms required by Article 50 TEU.
On 13 December 2017, the Government announced that the proposed votes on the agreements, expected in Autumn 2018, would have the following features:
The Government has also said that if the Commons fails to approve the agreements, the UK will leave the EU on 29 March 2019 without a deal.
The proposed votes in Parliament will have no direct legal effect on the status of the Withdrawal Agreement, nor any domestic legal effect.
On 13 November 2017, the Government announced that the Withdrawal Agreement, if approved, would be implemented in domestic legislation through the WAI Bill.
The UK is a dualist legal system, which means that international treaties to which it is a party must be implemented through domestic legislation to have domestic legal effect. If the WAI Bill could not be enacted, the UK would not be able to meet the legal obligations set out in the Withdrawal Agreement. As such, the votes on the WAI Bill will provide a further opportunity, albeit at a later stage in the process, for the Commons and the Lords to give their views on the Withdrawal Agreement.
The Government has since confirmed that the WAI Bill would need to be enacted before exit day, which is expected to be 29 March 2019. The Institute for Government has described the Government’s proposed timetable as “ambitious”, explaining that there “will be enough time, providing that nothing goes wrong”.
Clause 9 of the European Union (Withdrawal) Bill 2017-19 (EUW Bill) as introduced (now clause 11 of the Bill as amended on report in the Lords) contained a power to implement the Withdrawal Agreement through secondary legislation. It was amended in the Commons so that the power could only be used after a Bill to implement the Withdrawal Agreement (likely to be the WAI Bill) has been enacted by Parliament.
It is not clear how many of the provisions of the EUW Bill, particularly those that create “retained EU law”, will be used in the process of implementing the Withdrawal Agreement. For example, the WAI Bill could amend the EUW Bill in order to provide transitional arrangements.
During the report stage in the House of Lords, a new clause tabled by Viscount Hailsham was added to the EUW Bill which seeks to provide a legal framework for the parliamentary process of approving the Withdrawal Agreement through a motion in both Houses. The new clause would also grant Parliament a power to issue a legally binding direction to Government on the negotiations if either the Withdrawal Agreement is rejected or if no agreement was presented for approval to Parliament before exit day.
Under the Constitutional Reform and Governance Act 2010 (CRAGA), the House of Commons has the power to delay ratification of the Withdrawal Agreement repeatedly. The 2010 Act does not create a positive duty for a vote to be held in Parliament before a treaty is ratified. Further, for the House of Commons to resolve to delay ratification for 21 days, the Government or the Opposition would need to find the time for the debate and vote.
The Government has said that the vote on the agreements secured through the Article 50 process will include “the terms for our future relationship”. The Council of the European Union has said that as part of the Article 50 negotiations the EU and the UK will negotiate a “political declaration” on the framework for the future relationship, which will “accompany” the Withdrawal Agreement. The political declaration is not a legally binding treaty; it will likely set out negotiating objectives that will need to be turned into a treaty, which can then be approved and implemented once the UK has left the EU.
The substance of the political declaration on the future relationship will not have any domestic legal effect in the UK until a binding agreement(s) is negotiated with the EU and then approved, which can only occur once the UK has left. Once such an agreement is approved, parts of it will then need to be implemented in the UK through domestic legislation, presumably before the end of the implementation period.
The European Parliament will consider the political declaration while it is examining the Withdrawal Agreement, but it will do so in the knowledge that an Association Agreement or any other type of 'deep and comprehensive' free trade agreement under Article 218(6) of the TFEU will require its consent.
The UK Government has not said whether the UK Parliament would be granted a vote to approve the Treaty on the Future Relationship before the European Parliament is asked for its consent.
 David Davis, Written Statement Procedures for the Approval and Implementation of EU Exit Agreements, HCWS342 13 December 2017
 Council of European Union, Draft Guidelines on the framework for the future relationship, 7 March 2018
 In February 2017, the Government announced that it would “put the final deal that is agreed between the UK and the EU to a vote in both Houses of Parliament”, The United Kingdom’s exit from and new partnership with the European Union, Cm 9417 p.11
Commons Briefing papers CBP-8321
Authors: Jack Simson Caird; Sylvia de Mars; Vaughne Miller