At some point, probably early in 2017, the British Prime Minster is likely to trigger Article 50. A number of expert commentators and a large proportion of the British public still believe that it is a mistake for the UK to leave the EU. If it becomes obvious within the two-year countdown that triggering Article 50 was a bad idea, would it be possible to 'retract' a declaration under Article 50 and remain within the EU or would the UK be treated as a new applicant? How would this depend on whether this was supported by other EU members or not?


What is Article 50?

What are the UK's "constitutional requirements" for Article 50 notification of withdrawal from EU?

Could the UK re-join EU after leaving?

  • 3
    Are you talking about a unilateral withdrawal of notification, a withdrawal with the unanimous approval of the other members, or a withdrawal with the support of some but not all other EU members? A naive reading of the treaty itself seems to suggest these cases could have different outcomes.
    – origimbo
    Commented Sep 8, 2016 at 10:28
  • All of the above, really - now edited into question.
    – arboviral
    Commented Sep 8, 2016 at 12:58
  • 1
    It's not really a full answer (and I don't really like answering my own questions, although I know it's allowed) but yesterday Lord Kerr, the author of Article 50 explicitly said that yes, he thinks it could be un-triggered during the two-year period (bbc.co.uk/news/uk-scotland-scotland-politics-37852628).
    – arboviral
    Commented Nov 4, 2016 at 12:33
  • Huh - breaking news suggests the government might think the answer to this is "yes, we could": theguardian.com/politics/2016/nov/11/…
    – arboviral
    Commented Nov 11, 2016 at 16:32
  • 4
    Quick update for anyone still interested in this: The government doesn't know (2016-12-14) but Jolyon Maugham QC is trying to find out (2017-02-20). Watch this space!
    – arboviral
    Commented Feb 20, 2017 at 12:01

8 Answers 8


In a recent update to this issue, the European Court of Justice's Advocate General has issued a non-binding opinion that a country can revoke Article 50 unilaterally.

According to BBC News:

In a written statement, the ECJ said Mr Campos Sanchez-Bordona's opinion was that if a country decided to leave the EU, it should also have the power to change its mind during the two-year exit process specified in Article 50 of the EU treaty.

And it should be able to do so without needing the consent of the other 27 member states.

The official press release from the Court of Justice of the European Union says:

Advocate General Campos Sánchez-Bordona proposes that the Court of Justice should declare that Article 50 TEU allows the unilateral revocation of the notification of the intention to withdraw from the EU

That possibility continues to exist until such time as the withdrawal agreement is formally concluded.

On the 10th Of December 2018, this position was confirmed by the ECJ.

The court concluded that any EU member state can revoke the article 50 process without needing approval from every other member state, in an emergency judgment timed to coincide with Tuesday’s critical Commons vote on Theresa May’s Brexit deal.

It said: “The United Kingdom is free to revoke unilaterally the notification of its intention to withdraw from the EU.”


There is no definitive answer to this question and it's not even clear if it is political (to be decided by the European Council) or a legal question (to be decided by the European Court of Justice). Probably both in reality.

Let's say there was a snap general election in the UK and a coalition of pro-Remain parties became the Government with Nick Clegg as Prime Minister. PM Clegg then lays a bill before Parliament to repeal the EU (Notification of Withdrawal) Bill. Once that is passed he then writes to the Commission notifying them that Britain is withdrawing its Article 50 notification.

There is no provision for withdrawal in Article 50 itself however it does say “Any member state may decide to withdraw from the union in accordance with its own constitutional requirements.”. At this stage clearly the UK constitutional requirements are not met and therefore it would seem that the article 50 notification is null and void.

After that the Council and Commission may decide to treat the Article 50 notice as never having been given and proceed on that basis (likely outcome I would think). Alternatively they could decide that the notice is still valid and insist the UK leave (very unlikely).

Regardless of what the Council and Commission decide an aggrieved party could raise a Court action to challenge the decision and to insist that the UK has to leave the two years after notice was given. The likelihood of someone raising that action is very high, however I doubt it would be successful nevertheless it would surely consume many hours of billable time for the lawyers!

Bottom line - anyone who tells you there is a definitive answer to this is wrong!

  • 4
    I'm not following your reason. Article 50 describes an action, "decide". An action happens at a specific moment, and is governed by then-current law. In particular, the UK's constitutional requirements governing the aforementioned decision are those of March 2017. A later change in constitutional law cannot retroactively make that decision unconstitutional. Realistically, if the UK does change its mind, they can just reapply. This is easy as they are still a member and meet most criteria. But such readmission would mean giving up UK-specific waivers, e.g. mandatory introduction of the Euro.
    – MSalters
    Commented Apr 3, 2017 at 14:26
  • 1
    Update: snap election is no longer hypothetical but now looks almost certain.
    – gerrit
    Commented Apr 19, 2017 at 12:29
  • 1
    I believe this answer is wrong on a few counts: (1) that there is some possibility of a revocation being a political, rather than a legal, issue; (2) the idea that repealing the EU (Notification of Withdrawal) Act would retrospectively make an action unconstitutional; (3) that the "in accordance with its own constitutional requirements" in Article 50(1) creates a condition for giving notice under the separate Article 50(2); also, and this part is more subjective, I lean more towards saying a court challenge would be successful. I'll elaborate on all of this in my answer.
    – JBentley
    Commented Apr 19, 2017 at 12:43
  • 3
    There is now a movement towards a definitive answer, which I've added as a separate Answer, but might be better as an update to this one. bbc.co.uk/news/uk-scotland-scotland-politics-46428579
    – Jontia
    Commented Dec 4, 2018 at 10:37
  • 1
    This answer is out of date.
    – gerrit
    Commented Dec 16, 2018 at 9:46

Article 50 is only 250 words, and has no provisions for canceling a request once issued.

Once Article 50 is formally triggered, by a Head of Government (Prime Minister Theresa May) notifying the European Council that it is invoking Article 50, there is no provision written to withdraw or cancel that notification.

Upon invoking Article 50, a 2 year clock begins tolling. If terms of an exit have not been successfully negotiated by the end of 2 years, the member state is simply "kicked out". All benefits, agreements, treaties, terms of EU membership are simply canceled.





  • 11
    Nit-picking mode: Elizabeth II is the head of state for the UK...
    – DJohnM
    Commented Sep 8, 2016 at 17:48
  • Well, point 3 gives the option of delaying the negotiations for, say, a century or two (or more realistically, for 3 or 4 years to approve a new version of article 50). That said, those possibilities are highly improbable.
    – SJuan76
    Commented Sep 8, 2016 at 18:57
  • 3
    @SJuan The principle sticking point being that delay requires unanimous agreement between the rest of the European council. Although if that actually occurred then ratification of a treaty amendment to modify article 50 would be simpler than in any other case.
    – origimbo
    Commented Sep 8, 2016 at 20:23
  • 3
    There is a strong and widespread view among UK Constitutional lawyers (Britain has no written constitution, its principles being embedded in Common Law and precedent) that it would be unlawful for the UK Government to invoke Article 50 without an Act of Parliament The majority of MPs are believed still to be in favour of Remaining.
    – WS2
    Commented Sep 9, 2016 at 13:50
  • This answer is out of date.
    – gerrit
    Commented Dec 16, 2018 at 9:47

I do not agree with the answer which says it is unclear whether it would be a political or a legal issue. Unless someone can provide evidence to the contrary, I believe that it is certainly a legal issue, and one that the European courts have jurisdiction over. Whether or not an Article 50 notice is revocable is uncertain, but whilst I personally see compelling reasons for it not being revocable, I haven't actually seen any reasoned arguments on the other side, other than politicians and other commentators giving their (unsubstantiated) opinions. If anyone has access to any concrete legal arguments for a notice being revocable, it would be great to post them as answers here.

The hierarchy of laws in the EU is essentially this:

  1. EU primary legislation: Treaties (TEU and TFEU)
  2. EU secondary legislation: Regulations, Directives, Decisions
  3. Member State law

A reasonable approximation to this exists in the USA where you have the Constitution (~EU primary legislation), federal law (~EU secondary legislation) and state law (~Member State law).

In general, each level in the hierarchy takes precedent over the levels below it, although the rules of enforcing EU law in a Member State are complicated (and I won't go into them here).

Article 50 is found in the TEU and as such is at the top of the hierarchy. The treaties define all aspects of how the EU operates and what powers it has. An EU institution such as the Council or the Commission exists, and has powers, because of the treaties. For that reason, unless the treaties specifically give jurisdiction to an EU institution to determine whether or not an Article 50 notice is revocable, then they do not have that jurisdiction, and it falls to the courts. They will make their decision in the same way that they make all decisions: by interpreting the law (in this case, the treaties). To do that they'll be assisted by various things such as previous cases, the purpose of the law (i.e. the intention of the drafters), principles of interpretation, etc.

The relevant paragraphs of Article 50 for our purposes are 1 - 3:

  1. Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements.
  2. A Member State which decides to withdraw shall notify the European Council of its intention. [rest of paragraph cut].
  3. The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.

It has been argued in another answer that a future government could hypothetically repeal the European Union (Notification of Withdrawal) Act 2017 and that this would make the already issued notification fall foul of Article 50(1) as the "constitutional requirements" wouldn't be met. Paragraph 1 of that act states:

The Prime Minister may notify, under Article 50(2) of the Treaty on European Union, the United Kingdom’s intention to withdraw from the EU.

The Act received Royal Assent on 16th March 2017 and the UK notified the Council on 29th March 2017. Since the Act hadn't been repealed beforehand, the Prime Minister was acting lawfully when she submitted that notification. Repealing the Act would merely remove the power to notify from the Prime Minister going forward.

In any case, even if the Prime Minister's past notification could somehow be retrospectively made unlawful, it won't have an effect in EU law. Article 50(1) requires that the decision to withdraw be made "in accordance with [the Member State's] own constitutional requirements". Clearly that requirement was satisfied when the decision to withdraw was made. The actual notification itself is dealt with in 50(2) which says nothing about constitutional requirements.

Moving on, there is currently legal uncertainty as to whether or not a notice can be withdrawn, and there is plenty of legal opinion on both sides of the debate. We can't know for sure unless a case comes before the EU courts.

However, in my opinion, there are serious obstacles in the way of a notice being revocable. It is often said that Article 50 is "silent" on withdrawal of a notice. I do not believe this to be the case. I believe it very clearly rules out such a possibility.

Article 50(3) provides:

The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.

It seems clear to me that the word "unless" (emphasised by me above) was intended by the drafters to cover the circumstances under which the rule which comes before it can be ignored. There is a principle of statutory interpretation, "the express mention of one thing excludes all others" (in latin: Expressio unius est exclusio alterius). The drafters of Article 50 have provided exactly one method of avoiding EU withdrawal 2 years following notification (in the absence of a withdrawal agreement) after the word "unless": unanimous agreement of the Council to extend the period for reaching agreement. Or to put it another way, it unambiguously states that unless there is a unanimously agreed extension, then the Member State will no longer be in the EU either after 2 years from notification, or in accordance with the withdrawal agreement. If the drafters had intended for a notice to be revocable, then they had their chance to provide for this after the word "unless". They didn't, so we must assume that it wasn't intended for this to be possible.

Another compelling argument is the actual provision for extending the 2 year period in which agreement must be reached, which requires unanimous agreement of the other Member States via the Council. Allowing a notice to be withdrawn would essentially make a nonsense of this provision, as a Member State wanting to extend beyond 2 years could simply withdraw their notice and resubmit it the next day, thus gaining an additional 2 years without any agreement from the other Member States. It can't have been the drafters' intention to allow this requirement to be so easily circumvented.


I thought it worth mentioning another couple of possibilities:

  1. The EU treaties could be modified to specifically allow the notice to be withdrawn. However, this would require unanimous agreement of all Member States and historically has been difficult to achieve, and slow when it has been achieved. I suppose one could imagine a scenario where the Council agrees to extend the agreement period using Article 50(3), to allow sufficient time for Treaty change.

  2. The withdrawal agreement could be finalised simultaneously to an Article 49 agreement. Article 49 describes how a new state may join the EU. If the Article 49 agreement was worded to provide for the UK retaining the same membership terms as it has now, then the effect would be the same as if notice was withdrawn. The requirements for achieving an Article 49 agreement are even more stringent than for achieving an Article 50(3) extension: unanimous agreement of the Council, absolute majority of the European Parliament, and ratification by each Member State.


There is now an official answer to this question.

Specifically, the European Court of Justice has stated that the UK parliament (not HM Government), can unilaterally revoke Article 50 as long as withdrawal has not already occurred.

  • Did you notice the other recent answer from Jontia? Commented Dec 10, 2018 at 12:03
  • 1
    @Trilarion The ECJ only gave its definitive view today, Dec 12, 2018. As Jonita stated in that answer, the Advocate General's statement was an opinion. This is the formal ruling. Everything was supposition prior to this, no matter how well informed.
    – Alex
    Commented Dec 10, 2018 at 12:38
  • 3 hours ago Jontia added the same content you added one hour ago. That's why I asked. Commented Dec 10, 2018 at 12:55

According to the (British!) politician who drafted Article 50 it is revocable during the two year period. I also read something which I can't find the link to that says that the EU leadership believes that it is revocable as well.

I'm inclined to agree with Alan Dev that it might not be as definitive as that, however, Lord Kerrs opinion should carry some weight.

As a side note, if the EU negotiators believe that the UK can be bullied into revoking article 50 by making any negotiated settlement as damaging and unpalatable as possible, the next two years could be interesting.

  • 1
    I don't see how such a thing could practically be made revocable for the whole two years. It might have been reasonable to write the rules so that notice could be withdrawn in the first year if the country which issued the "false" notice pays a specified penalty, in which case anyone considering making expensive preparations for Brexit would know that they might want to defer them until 12 months after notice was given, but it would be absurd to suggest that Britain should retain the right to unilaterally cancel Brexit all the way up to the scheduled date.
    – supercat
    Commented Apr 19, 2017 at 20:03
  • This would be a valid point if supported by more than the opinion of the person who drafted the Article in question. In practice Article 50 is an unknown quantity until it's used and tested by the EU's Constitutional arrangements - most likely by an attempt at unilateral withdrawal of the invocation followed by an authoritative adjudication on the matter by a court or authoritative body. Commented Apr 20, 2017 at 10:17
  • And the adjudicating court will be in the EEC rather than England so I'm inclined to think it's more likely to side with the stated intention of the person drafting it. Especially if that reduces the chances of the UK actually leaving. The EEC (and probably the UK as well) are better off united so the EEC will want to facilitate the withdrawal of Article 50 should the UK come to its senses during the next couple of years...
    – mcottle
    Commented Apr 20, 2017 at 15:23
  • 2
    The opinion of a drafter carries very little weight. The intent of the drafter at the time of drafting is what matters, and that will be a matter of legislative interpretation. The way Article 50 is worded, it is hard to contemplate that it was intended for a notice to be withdrawal, for reasons I outlined in my answer (in particular, it would make a mockery of the extension provision).
    – JBentley
    Commented Dec 15, 2017 at 10:03

The answer is extremely simple. Given an unanimous agreement of all EU members pretty much anything is possible - they could even decide to admit New Zealand into the Union if they really wanted to. There is of course the European Court of Justice but it is pretty much helpless should the Member States agree on something in full concert. Remember that states don't follow the law as it is seen by a common person - they can pretty much rewrite it as they go with no one to stop them.

However should there be at least one state that disagrees with the UK coming back (say, Spain wants to take back Gibraltar as a token of gratitude for casting its vote) then nobody really knows. The ECJ could rule one way or the other. The European Commission might come up with a clever legalese trick to keep them. At this point this is mere speculation that is reliant on the attitudes of 28 member state governments at some point in the future rather than on what's written in the books.

  • 2
    "They could even decide to admit New Zealand into the Union if they really wanted to." is incorrect. See en.wikipedia.org/wiki/Copenhagen_criteria Commented Feb 13, 2018 at 16:10
  • 1
    @DenisdeBernardy if you have unanimous consent all existing rules go out the window (barring international agreements with non-EU states). The 28 member states could decide they no longer want to abide by the Copenhagen criteria and that would be the end of story. Commented Feb 13, 2018 at 16:18
  • 2
    It's not that your conclusion is a complete fabrication, but it's so devoid of sources and of any information about the relevance of the several EU institutions that I don't see how could it be of any help to anyone seeking more educated elaboration than one can get at the nearest pub after a couple of pints.
    – armatita
    Commented Feb 13, 2018 at 17:04
  • @armatita no further insight can be gained from studying the existing laws. Either there's unanimous consent that the UK should stay (in which case all laws are irrelevant) or there's not, in which case it would take an ECJ ruling and lots of political maneuvering to reach one outcome or the other. At this point anyone trying to guess is merely fooling others into thinking they've gained additional insight into the future. I'd bet that not even Juncker knows the answer. Commented Feb 13, 2018 at 17:09
  • 1
    This answer is kind of correct, but in practice it wouldn't work out like this. "Rewrite it as they go with no one to stop them" means changing the treaties, and is far from as simple as that phrasing suggests. Historically it has been slow, painful, and often fails. See e.g. here for a summary of how treaty change works. The important factor here is that such change would have to come before the withdrawal kicks in, which even at the time the answer was posted (but especially now) is highly unlikely.
    – JBentley
    Commented Nov 22, 2018 at 10:59

The short answer is: not possible

British media has sometimes claimed that UK could unilaterally cancel the Brexit process even after triggering Article 50.

For example, this article in The Guardian (dated October 7th, 2017) says that:

The prominent lawyer Jessica Simor QC, from Matrix chambers, has written to May asking her to release the legal advice under the Freedom of Information Act. Simor says she has been told by “two good sources” that the prime minister has been advised “that the article 50 notification can be withdrawn by the UK at any time before 29 March 2019 resulting in the UK remaining in the EU on its current favourable terms.

This sort of stories however are unsubstantiated as there is no information on the authority behind the claims that Britain can unilaterally cancel the Article 50 process.

The European Union official Q&A page on Article 50 has, however, this to say about the matter (emphasis added):

Once triggered, can Article 50 be revoked?

It is up to the United Kingdom to trigger Article 50. But once triggered, it cannot be unilaterally reversed. Notification is a point of no return. Article 50 does not provide for the unilateral withdrawal of notification.

Also further up on the same page the following question is answered:

When does the United Kingdom cease to be a member of the European Union?

The EU Treaties cease to apply to the United Kingdom from the date of entry into force of the agreement, or within 2 years of the notification of withdrawal, in case of no agreement. The [European Union] Council may decide to extend that period by unanimity.

So although British media can say what they want, the reality is that there is no legal recourse for UK to unilaterlly cancel the withdrawal process.

Anything else is just wishful thinking.

  • 2
    Based on the latest news, this answer is now incorrect. bbc.co.uk/news/uk-scotland-scotland-politics-46428579
    – Jontia
    Commented Dec 4, 2018 at 10:38
  • @Jontia: The ECJ still hasn’t decided. It isn’t bound by the opinion of the advocate general.
    – chirlu
    Commented Dec 5, 2018 at 8:21
  • @chirlu I agree, in fact the last line of my answer above states this explicitly. But eulawanalysis.blogspot.com/2016/01/… says the court follows the advocate general's position 70% of the time and out-law.com/page-11458 says since 2003 the AG only comments on cases involving new questions of law. So while not bound it is very likely to agree. So at least the "wishful thinking" is inaccurate.
    – Jontia
    Commented Dec 5, 2018 at 8:28
  • 1
    @Jontia: 70% agreement means 30% non-agreement. :-) And there are lots of high-profile cases where the court decided differently. We’ll need some more patience.
    – chirlu
    Commented Dec 5, 2018 at 8:42
  • ECJ have now confirmed UK can withdraw Article 50 notice. theguardian.com/politics/2018/dec/10/…
    – Jontia
    Commented Dec 10, 2018 at 9:05

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