After the brexit referendum results came in, there has been a lot of talk about Article 50 of the Treaty on European Union:

  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. In the light of the guidelines provided by the European Council, the Union shall negotiate and conclude an agreement with that State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the Union. That agreement shall be negotiated in accordance with Article 218(3) of the Treaty on the Functioning of the European Union. It shall be concluded on behalf of the Union by the Council, acting by a qualified majority, after obtaining the consent of the European Parliament.

  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.

  4. [...]

It is possible to imagine a scenario where the UK invoke Article 50, but then change their mind and don't want to leave (e.g. because the negotiated deal was not good enough, or because of new elections). It is also reasonable to believe that the EU would be happy to keep the UK.

From the news I am given the impression that the UK would have to leave if they invoked Article 50 even if both the EU and the UK agreed that it would be better if they stayed. Is that so?

  • The negotiated agreement is that the UK will leave in 999 years.
    – Dale M
    Commented Jun 29, 2016 at 0:02
  • 1
    That is a matter of some debate; see, for example, this article. There does not appear to be a definitive answer at present. Of course, the EU could change the rules later to clarify this; but this doesn't appear to have been mentioned yet. Commented Jun 29, 2016 at 14:02
  • @SteveMelnikoff Great article, thanks! If you were to post the link together with a summary or quote I would be happy to upvote and accept.
    – Anders
    Commented Jun 29, 2016 at 14:40
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    I edited my answer to add more detail.
    – Sefe
    Commented Nov 17, 2016 at 23:11

3 Answers 3


You often have the situation in legal science and practice that a certain situation is not clearly addressed by the law. In these cases you are left to interpret the law. That means you infer from the cases that are addressed by the law to those that aren't. There is a whole lot of techniques to do that (by the word if the law, by its context, by its history etc.). There is a lot of arguments you can make (e.g. to consider an extreme case that borders to the absurd, called argumentum ad absurdum). That is what you learn at law school. Everyone can read the law, but to apply it you need a lawyer.

Given the sheer amount of ways to make your argument, it is no wonder that lawyers often disagree drastically in their interpretations of the law. So which opinion will prevail here remains to be seen. My personal 2 cents are that since the European treaties are designed to build a stable and lasting Union, most probably the opinion will win that you can cancel the process. But who knows, I could be wrong.


Let me elaborate more on the possible opinions on this case and where my opinion comes from:

Those opposed to the possibility to cancel could argue that in Article 49 you'll find the rules of admission to the Union and in Article 50 you'll find the rules for leaving the union. So you have clear rules for admission and clear rules for leaving. The absence of rules for cancelling means that this shouldn't be possible. If they would have wanted the possibility, they would have added it.

Those on favour of the option to cancel would say that it was merely forgotten when the treaty was drafted (that happens more often than you think). They would argue that nobody expected that a country would actually use the option (at least not anytime soon), so they wouldn't bother too much to consider all the cases.

Another argument in this direction is the intent of these regulations. The admission process is to make sure that a country is ready to join the Union, so you need a process to make sure of that. The process to exit the Union was installed because it doesn't make much sense to keep a country that doesn't want to be a member, so give them a way out. Now if a country changes their (collective) minds, would it make sense to not let them? The admission process is unnecessary since as a current member they are clearly ready. And since they don't want to be out anymore, the intent of the exit regulations is not met anymore. So why force them to continue?

Now, whatever argument you find more compelling (for me it's the second one), I believe a cancellation would be accepted. Why? The current situation is the Britain wants out and everyone else wants them to stay. If the UK change their minds now, there will be nobody anymore who wants them out. Since you can argue that cancellation is possible, why would anyone take the other side?

And even if there would be countries vetoing the cancellation, the case would probably go to the European Court of Justice in Luxemburg. There the UK would argue against the rest that they can stay (sounds absurd, doesn't it?). The Court has a history that in a case of doubt they would tend to take the decision that makes Europe stronger. Since Europe is stronger with the UK, I think chances are good that they would allow to stop the Article 50 process.

  • "The admission process is unnecessary since as a current member they are clearly ready.". Actually, there's a critical difference. The admission process disallows certain opt-outs. In particular, the UK has multiple opt-outs not available to new members including a rebate, an exemption from labor laws and an exemption from the EMU (Euro). If Article 50 can be cancelled, the UK would keep those opt-outs; if readmission is via Article 49 then those exemptions are lost.
    – MSalters
    Commented Jan 30, 2017 at 16:41
  • @MSalters: At the end it would be a political decision. And that would mean they wouldn't cause trouble on brexit from brexit.
    – Sefe
    Commented Jan 30, 2017 at 16:51
  • @MSalters anyway, as often in law there are enough arguments and counter-arguments to take a side.
    – Sefe
    Commented Jan 30, 2017 at 19:44

With current EU law, the UK would have to leave after two years, unless they ask for an extension of the two year limit, and the request is accepted by the EU with the suitable majority.

The idea of this extension is of course that if it turns out negotiations would take 27 months instead of 24 months for example then this can be handled in a reasonable and civilised way. But I don't see why the UK couldn't ask for an extension for 900 years and the EU couldn't agree to that. That would be a bit sneaky, and the state of the UK would be a bit strange, but I can't see why this would be impossible.

And I can't see why the EU couldn't pass a law that allows a country to withdraw from the withdrawal process altogether if that request is accepted by the EU. So even though today the process cannot be stopped, that could change.

  • Countries are not allowed to unilaterally cancel the process, because they could then stay in the "leaving" phase forever. This was intentional, due to the politics going on at the time it was being drafted. (potentially autocratic country maybe leaving abruptly)
    – bobsburner
    Commented Oct 9, 2019 at 13:02

Apparently, the ECJ has now ruled that the UK can unilaterally withdraw from the article 50 process. From the BBC:

The European Court of Justice has ruled the UK can cancel Brexit without the permission of the other 27 EU members.

The ECJ judges ruled this could be done without altering the terms of Britain's membership.

The Judgement of the European Court of Justice, 10 December 2018, case C-621/18:

Article 50 TEU must be interpreted as meaning that, where a Member State has notified the European Council, in accordance with that article, of its intention to withdraw from the European Union, that article allows that Member State — for as long as a withdrawal agreement concluded between that Member State and the European Union has not entered into force or, if no such agreement has been concluded, for as long as the two-year period laid down in Article 50(3) TEU, possibly extended in accordance with that paragraph, has not expired — to revoke that notification unilaterally, in an unequivocal and unconditional manner, by a notice addressed to the European Council in writing, after the Member State concerned has taken the revocation decision in accordance with its constitutional requirements. The purpose of that revocation is to confirm the EU membership of the Member State concerned under terms that are unchanged as regards its status as a Member State, and that revocation brings the withdrawal procedure to an end.

(TEU = The Treaty on European Union)

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