Turning back the clock – can the UK’s Article 50 notice be revoked unilaterally?

10th Dec 2018

Mathias Cheung discusses the Advocate General’s opinion and the CJEU’s ruling on unilateral revocation of the UK’s Article 50 notice:

  • The Advocate General opined that the UK has the sovereign power to revoke its Article 50 notice at any time before the withdrawal takes effect.
  • The CJEU followed the Advocate General’s opinion, and the option of staying in the EU has become a legally viable option for the UK.
  • There would be significant hurdles to overcome before the UK could formally decide to revoke its Article 50 notice, but there should be an open and informed debate on all available options.


The end is nigh for UK’s membership in the EU – or at least, that was thought to be the inevitable result until recently. Since the publication of the controversial draft withdrawal agreement on 14 November 2018, there has been widespread public debate regarding the merits (and indeed the demerits) of the proposed Brexit deal and the prospect of a “no-deal” Brexit.


The debate has been somewhat binary, with the Members of Parliament (“MPs”) and the British public being presented with a stark choice between the proposed withdrawal agreement or no deal at all. Things took an interesting turn, however, when Advocate General Campos Sánchez-Bordona (“AG”) of the Court of Justice of the European Union (“CJEU”) handed down his opinion in Case C-621/18 Wightman and Others v Secretary of State for Exiting the European Union (“Opinion”), followed swiftly by the CJEU’s ruling (“Judgment”) in less than a week.

Court of Justice of the European Union

Throughout the proceedings in Luxembourg, the UK Government has maintained the stance that the question referred for a preliminary ruling is inadmissible because it is hypothetical and theoretical, as there is no indication that the UK Government or Parliament are going to revoke the Article 50 notice. This very much reflects the UK Government’s mentality throughout the Brexit negotiations i.e. remaining in the EU is distinctly not an option.

The AG disagreed with the UK Government’s position, reasoning that the question is not academic as it relates to Article 50 TEU ‘which is actually in the course of being applied and the future legal consequences of which are drawing inexorably closer’, and the ‘practical, and not only theoretical, importance of the Court’s answer is obvious, given Brexit’s enormous legal, economic, social and political repercussions’ (paragraphs 40-41 of the Opinion). The CJEU similarly rejected the plea of inadmissibility (paragraphs 20-36 of the Judgment).

The AG notably acknowledged that ‘the question cannot be characterised as superfluous or unnecessary either, since the answer will have the effect of clarifying the options open to MPs when casting their votes’ (paragraph 43 of the Opinion). This was no doubt one of the key drivers for the CJEU to deliver its Judgment within such a short timeframe. In the event, both the AG and the CJEU concluded that any Article 50 notice can be revoked unilaterally without requiring the unanimous consent of the other Member States.

The AG specifically relied on Article 68 of the Vienna Convention on the Law of Treaties (“VCLT”) as an interpretative guideline – it provides that a withdrawal notification may be revoked at any time before it takes effect (paragraphs 71-85 of the Opinion). This interpretation is consistent with the travaux préparatoires of the EU treaties (paragraphs 138-141 of the Opinion), and the CJEU considered that these materials all militate in favour of the unilateral revocation of an Article 50 notice (paragraphs 70-71 of the Judgment).

The AG rightly pointed out that ‘unilateral revocation would also be a manifestation of the sovereignty of the departing Member State’ (paragraph 94 of the Opinion). In my view, this does not trespass on the primacy of the EU as a new and autonomous international legal order restricting the sovereignty of the Member States (see e.g. Case 6/64 Costa v ENEL at paragraph 3; Opinion 2/13 on Accession of the EU to the ECHR at paragraph 157), given that Article 50 is silent on the issue of revocation.

It is therefore unsurprising that the CJEU expressly endorsed the AG’s reasoning based on sovereignty (paragraphs 57 to 58 of the Judgment). In the CJEU’s words, ‘given that a State cannot be forced to accede to the European Union against its will, neither can it be forced to withdraw from the European Union against its will’, which would effectively be the case if other Member States have the power to veto a proposed revocation of an Article 50 notice (paragraphs 65-67 of the Judgment).

The AG recommended that any revocation decision must be (i) formally adopted by the Member State in accordance with its constitutional requirements, and (ii) in accordance with the principles of good faith and sincere cooperation i.e. a Member State cannot use successive notifications and revocations in order to improve the terms of withdrawal (paragraphs 142-156 of the Opinion). Interestingly, the CJEU’s Judgment stopped short of imposing the second condition, leaving the door wide open for unilateral revocation of an Article 50 notice irrespective of the Member State’s ultimate agenda.

The AG’s Opinion and the CJEU’s Judgment now present the UK with a ‘third way’ forward, namely to turn back the clock and keep the UK within the EU. For the first time since the EU referendum, remaining within the EU has become a legally viable option, and for a construction industry which has just reported the weakest rate of expansion in six months, this is not something that can or should be dismissed out of hand.

Indeed, the AG did not shy away from emphasising that ‘revocation of the notification to withdraw, by halting the notifying Member State’s departure from the European Union, ensures that the citizens of that Member State, as well as those of the other Member States, continue to enjoy the rights of citizenship set out in the FEU Treaty and in the Charter’ (paragraph 135 of the Opinion). The CJEU also expressed similar sentiments to that effect (paragraph 64 of the Judgment).

Lord Kerr, who was the secretary general of the European convention which drafted Article 50, wrote in a recent Op-Ed that the AG’s Opinion is legally sound and consistent with the drafters’ intention, and he pointed out in no uncertain terms that ‘the choice is between a bad Brexit deal and sticking with the deal we have in the EU. And it’s a choice for the people’. This has become all the more relevant in the light of the CJEU’s Judgment.



However, for the UK to undo the result of the EU referendum, the hurdles are by no means easy, as rightly noted by David Allen Green in the Financial Times. It is unlikely that anything short of a general election or a formal second referendum could achieve the revocation of the Article 50 notice, and with 29 March 2019 fast approaching, a decision to put this option to a vote would most likely require an extension of the Article 50 deadline.

What is certain is that an open and informed debate about all the available options (including revocation of the Article 50 notice) ought to be had in the coming days, given the irrevocability of withdrawal and the potential consequences which the UK would have to live with in the decades to come. To this end, the construction industry has a significant stake in the outcome of this debate, and there is much to be said for the industry to make its voice heard.


Mathias Cheung


Mathias’ practice covers all areas of Chambers’ work, including construction, engineering and infrastructure, energy and utilities, information technology, and professional negligence. In addition to these specialist areas, he has gained experience in a wide range of commercial disputes, including cases on fraud, insurance, assignment, subrogation, and conflicts of law. Mathias is also the winner of the SCL Hudson Prize 2015 for his essay entitled ‘Shylock’s Construction Law: the Brave New Life of Liquidated Damages?’.

As a native of Hong Kong, Mathias is fluent in both Cantonese and Mandarin, and he is therefore able to take instructions for cases involving Chinese-speaking parties and Chinese documentation in Hong Kong, Mainland China, Singapore and other jurisdictions.

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