Information regarding Brexit negotiations is available from the European Commission "State of Play of Article 50 negotiations with the United Kingdom" and at the Commission's dedicated website and also from the UK Department for Exiting the European Union - HERE.
The Prime Minister "triggered" Article 50 on 29th March 2017 - see Plan for Britain. The Commission's "state of play" document asks whether the Article 50 notification can be revoked and offers the stark answer: ".... once triggered, it cannot be unilaterally reversed. Article 50 does not provide for the unilateral withdrawal of the notification." [My emphasis].
The EU refers here to unilateral withdrawal. Nothing is said about whether the notification can be withdrawn by agreement and there appears to be no reason why the EU and the UK could not agree to "forget the whole thing."
Interestingly, it is not beyond doubt that the Commission's view about unilateral reversal is correct. Article 50 does not state the position one way or the other. Here is some of the opinion on this important issue.
The background to Article 50 TEU is set out in a Briefing issued by the European Parliament in February 2016. There appears to be a concern that notice under Article 50 might be misused by a Member State in order to secure treaty changes. For this reason, the briefing paper favours the view that unilateral withdrawal of notice is not possible. Certainly, giving notice of a decision to leave, was never meant to be a step to be taken lightly. It triggers the 2 year period at the end of which the Member State leaves the EU unless there is either a withdrawal agreement or an agreed extension to the 2 years. On a literalist - "black letter" - reading of Article 50 it is entirely possible to reach the conclusion that it is not permissible to unilaterally revoke a notification.
House of Lords view in 2016:
In the Miller and Dos Santos litigation, it was an agreed position between the parties that notice given under Article 50 could not be withdrawn - Brexit litigation: Supreme Court gives judgment (27th January 2017). Nevertheless, legal opinion varies on this as the following selection of articles amply demonstrates.
A) In early July 2016, Dr Philip Syrpis (Bristol University) published his analysis of the EU law questions surrounding Article 50. Please see Part 1 and Part 2. In Part 1, Dr Syrpis considered the arguments surrounding the revocation of notice question and suggested that an answer be obtained, if necessary, by an action in the Court of Justice of the EU. Regrettably, as things stand, there is no definitive answer and there is notable opinion either way.
B) Writing on the UK Constitutional Law Group blog, Jake Rylatt (College Research Associate, Wolfson College, Cambridge) concluded that the stronger argument is that an Article 50 withdrawal notification may not be unilaterally revoked by the Member State concerned -see:
J.W. Rylatt, ‘The Irrevocability of an Article 50 Notification: Lex Specialis and the Irrelevance of the Purported Customary Right to Unilaterally Revoke’ U.K. Const. L. Blog (27th July 2016) (available at: http://ukconstitutionallaw.org)).
C) Recently, the question of revocation arose in relation to the fact that, in March 2017, the British government also notified that it would be leaving EURATOM - another of the "European Communities" to which the UK acceded in 1973. Professor K A Armstrong (Professor of European Union Law, Cambridge) - Opinion: Brexit, Euratom and Article 50 - notes:
"The wording of Article 50 does not tell us whether amendment or revocation is possible. A European Commission Press Release does state that notification is a ‘point of no return’ and does not provide for ‘unilateral withdrawal of notification’. This is simply the opinion of the Commission and has no binding legal quality. Only the Court of Justice can decide this question. And there is legal opinion which considers that notification is open to revocation, including without the consent of the other EU governments."
D) A further article of interest is Jeroen Jansen - "Step by step guide to the UK's exit from the EU - 29th March 2017.
"Although the UK Government is adamant that the legal effect of Article 50 is irrevocable once triggered, international treaty law has a role to play. Article 68 of the Vienna Convention on the Law of Treaties 1969 states that a party that gives notice of its intention to withdraw from a treaty can revoke that notice at any time before it takes effect. But the legal position is not clear and there is a question mark over whether the Vienna Convention even applies: One view holds that the TEU creates an autonomous and special legal order which should not be interpreted by reference to other external international standards and that Article 50 amounts to a complete code for withdrawal. The TEU itself is silent on the position and the travaux préparatoires provide no conclusive guidance.
The question of whether the notice can be revoked or not could have considerable significance in terms of tactics around exit negotiations. In the view of the EU institutions and a majority of the remaining Member States, this is more of a political than a legal question. There is general consensus in Brussels that once the UK triggers Article 50, there is no turning back."
E) There is also the "Three Knight's Opinion" published by Bindmans Solicitors - Opinion (pdf). The opinion considered whether notice could be given "conditionally" but, as we know, the UK government did not seek to impose any conditions on the 29th March notice. The opinion stated that: "There are very strong arguments that Article 50 permits a Member State to notify its intention to leave the European Union subject to the fulfilment of ... constitutional requirements, and that a notification under Article 50 may be unilaterally revoked if those constitutional requirements are not met."
F) Nick Barber, Tom Hickman and Jeff King "Pulling the Article 50 trigger: Parliament's indispensable role" set out Article 50 TEU and commented - "The first point to note about Article 50 is that it is a once-and-for-all decision; there is no turning back once Article 50 has been invoked. If no acceptable withdrawal agreement has been reached after two years, the exiting Member State is left without any deal with the EU. It is of course possible to extend the time period. But this is in the gift of the EU Council and requires its unanimous agreement.
It may be argued that implicit within paragraphs 2 and 3 is a right for the member state to revoke the notice to withdraw. Yet this argument depends on reading such a right into a text from which it is conspicuously absent. That text clearly provides that only the terms of withdrawal itself are negotiable and states that if agreement is not reached then the Treaties cease to apply to the State concerned. The point is however probably moot since the UK must trigger Article 50 expecting and intending to exit the EU. And it could not safely assume that it is able to withdraw notification on the basis of the terms of Article 50."
N. Barber, T. Hickman and J. King, ‘Pulling the Article 50 ‘Trigger’: Parliament’s Indispensable Role’, U.K. Const. L. Blog (27th Jun 2016)
This document noted in relation to what ultimately emerged as Article 50 that - "The procedure provided for in this provision is partly based on that provided for in the Vienna Convention on the Law of Treaties."
The document is archived by the University of Luxembourg Research Centre. The CVCE.eu research infrastructure permits access to thousands of documents and publications on the European integration process.
What if the issue got to CJEU?
IF this question were to get to the Court of Justice of the EU then how might Article 50 be interpreted? This question is not readily answerable but, as part of its decision-making process, the court would undoubtedly consider the full history of Article 50 going back to when a Withdrawal Clause first appeared in the Draft EU Constitution which preceded the Lisbon Treaty 2009.
An article by Piet Eeckhout and Eleni Frantziou - Brexit and Article 50 TEU: A constitutionalist reading (December 2016) - notes the absurdity of forcing a member state to leave if that state has changed its mind. They conclude (at pages 37 to 41) that unilateral revocation may be possible. If a Member State could not remove its notification after changing its mind. and was thus forced to leave upon the conclusion of a two year period under Article 50(3), that would effectively amount to an expulsion from the Union - a possibility that was considered and rejected during the travaux. It would also be contrary to the principles of good faith, loyal cooperation, the Union's values, and its commitment to respect the Member States' constitutional identities. Thus, overall, provided that there is a new decision not to withdraw that is taken in good faith, the Article 50 clock can be stopped. After all, the goal of the Union is integration, not disintegration."
To say that a unilateral revocation (made in good faith following a genuine change of mind) is not possible appears to be both a denial of the sovereign rights of Member States and also contrary to the EU's aim of an ever closer Union - Article 1 TEU - "This Treaty marks a new stage in the process of creating an ever closer union among the peoples of Europe ..." Therefore, it seems to me to be eminently sensible to suggest that Article 50 permits unilateral withdrawal. Nevertheless, the contrary possibility cannot be discounted and, in this event, the UK will have already crossed the Rubicon so that there can be no retreat unless the EU Council agrees. We may never have the definitive judicial answer unless the question somehow gets to the Court of Justice of the EU. An attempt to do this via the Irish courts was abandoned earlier this year - Waiting for Tax: Sometimes you try and do not succeed.
Finally, at least for now, attention must be drawn to the view of Lord Kerr expressed in the House of Lords that a notice is NOT irrevocable within the 2 year period or any extension to that period. Article 50 is not an expulsion process. Lord Kerr was involved in the drafting of Article 50. See The Independent 21st February 2017 where Lord Kerr may be seen speaking in the House of Lords.