advocateThe CJEU’s ruling in C-621/18 Wightman and others clarifying that Member States can unilaterally revoke the withdrawal notification of Article 50 (2) TEU, is bound to have repercussions; in the case of Brexit and beyond.

In this piece I present my initial thoughts about the ruling and its possible legal and political implications. I argue that the CJEU’s ruling runs the risk of metamorphosing Article 50 from a ‘special protocol’, intended to be used only after serious reflection and with caution, into yet another political/negotiating arrow in the quiver of Member States.

According to my view, the formula that would ensure Article 50’s character as a ‘special protocol’, whilst not unduly limiting the sovereign rights of the departing MS to change its mind, should have the following characteristics : a) to advance a legally sound narrative; b) to permit the prospect of the reversal of the notification for withdrawal and c) but without creating perverse incentives that would lead to the ‘casualisation’ of Article 50 in the future, making the latter another ‘negotiating tool’ for Member States.

Ideally, the CJEU should have taken into account the impart of its interpretation of Article 50 TEU not only on the present case but more generally; namely its impact on the various other players whose reaction informs and affects the withdrawal process, for example the markets, and also its potential impact on the future possible use of Article 50 by other Member States.

Does the CJEU’s Interpretation fit these criteria?

The CJEU, following the AG’s Opinion, recognised the departing Member States’ right to revoke the notification of its intention to withdraw unilaterally during the period that it still has the status of an EU Member State, provided that such a decision is in line with the constitutional requirements of that Member State. However unlike the AG, who proposed an explicit conditionality of good faith in the exercise of this right- derived from the principle of sincere cooperation- the CJEU refrained from doing so, at least explicitly. Instead it simply stated that the revocation of the withdrawal notice must to be unequivocal and unconditional in the sense that its clear purpose should be the confirmation of the Member State’s EU membership and the end of the withdrawal procedure (paras. 74-75). The CJEU also clarified, that the period during which the MS can revoke its notification includes the extension of the withdrawal period agreed in accordance to article 50 (3).

In my view the CJEU’s ruling corresponds only to an extent to the formula that would prevent the ‘casualisation’ of Article 50.

Although the arguments for the existence of a right to revocation are by and large convincing, the arguments in favour of unilateral revocation are less so. Here are the reasons why:

First, the acknowledgement of a right of unilateral revocation means that the departing Member State is provided with a safety net which it can freely deploy. The knowledge of this fact may affect the negotiating stance of a departing Member State government in the future. It may lead in other words to a quite different approach compared with the cautious one that the UK government has adopted thus far. Furthermore, it may weaken the signalling from the markets, an important parameter for all the relevant players which particularly informs the choices of the departing Member State; perhaps markets would send weaker signals in the knowledge that the government has an unobstructed access to a ‘reset button.’

I believe that this interpretation of Article 50 raises the risk of ‘casualisation’ of the withdrawal process. Such a risk may not be evident with the current UK Government and perhaps this may explain the CJEU’s generous ruling in the present case. However, one needs not unbridled imagination to contemplate how Article 50 may be used in the future by other more audacious governments of populist persuasion. The temptation for considering the use (or the threat of use) of Article 50 as a tool for achieving concessions –as part of the Brussels political horse-trading habitat- is strengthened by the adopted interpretation because the decision to start the withdrawal process becomes less costly for the departing MS.

Furthermore, even in the context of Wightman I think that the recognition of the possibility for unilateral revocation of the withdrawal notification might do a disservice to the cause of the petitioners – who are trying to promote the cause of the UK remaining in the EU. Although they believe that a ruling confirming the possibility of unilateral revocation would assist their cause by showing that the process is reversible, in fact such a ruling could work against their intentions by strengthening the hand of the UK Government having an extra -secure- escape plan if things went badly. Moreover, it may weaken the signalling from markets –at a time where the Remain side needs strong negative market signalling to strengthen their case about the futility of Brexit wonderland.

Second, the requirement that the revocation be unequivocal and unconditional does not provide enough safeguards against the ‘casualisation’ of Article 50. Some thought experiments demonstrate the risks that ensue from this thesis: Is it possible for the Member State to change again its mind after the unequivocal and unconditional revocation of the first notification to withdraw? Following the CJEU’s logic, if the new decision to withdraw was taken in accordance with the Member State’s constitutional requirements, the answer must be affirmative. Otherwise the result would be that a State would remain in the EU against its will. How quickly can the Member State notify its new intention to withdraw? Can the Member State revoke it again? Based on the CJEU’s (current) position this sequence can continue ad infinitum.

Likewise, the idea that compliance with the constitutional requirements will function as a filter that prevents the proliferation of ‘tactical’ revocations, mentioned in the AG’s Opinion (para 156) and implicitly accepted by the CJEU, is not convincing either.

To begin with this observation is not entirely accurate in the case of the UK since it seems, at least-according to one plausible legal narrative, developed below- that the revocation can be effected by the Government without the need for Parliament’s authorisation -for the view suggesting that such revocation requires legislation see the excellent piece by piece by Phillipson and Young. This is because Parliament has not compelled the Government to proceed with the process of withdrawal. Section 1 of the EU (Notification of Withdrawal) Act 2017 reads: “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. Furthermore, the EU (Withdrawal) Act 2018 lies on the premise of a withdrawal process which began on the basis of the discretionary decision of the Government. Can the Government revoke this decision? I believe the answer is affirmative. This interpretation is supported by various provisions of the EU (Withdrawal) Act 2018. For example, although section 1 links the repeal of the European Communities Act 1972 with exit day, this provision cannot be construed in a way that necessitates such an exit day to ever occur (since there is no instruction by Parliament for Brexit to be effected); it simply explains what will happen to the ECA 1972 if and when exit day comes. Furthermore, the Act itself foresees the possibility for changing the exit day (currently set for 29 March 2019) by means of a regulation of a Minister (section 20 (4)). If such interpretation is followed this means that at least in the present case the constitutional requirements may not prove to be the buffer or the filter envisaged by the Court.

Even if we attempt to extract an implicit requirement for elections or a referendum from para 67  “…decides to revoke the notification of that intention though a democratic process” – a problematic proposition because it would entail the CJEU dictating what the constitutional requirements of Member States are- the situation would not change drastically. As suggested earlier it is perfectly conceivable, in this day and age, that episodes of the “withdrawal – revocation -withdrawal” sequence, described above, can be synchronised with national elections.

Alternative interpretations that would prevent the ‘casualisation’ of Article 50

I believe there are other interpretation that do not preclude the revocation of the notification but which at the same time minimise the risk of turning Article 50 into a political/negotiating arrow in the quiver of Member States. The interpretation of Article 50 which meets these parameters is the possibility to revoke the notification but with the approval of the Council.

Both the Court and the AG argued against this interpretation because it entails a veto right for every Member State which if exercised would in effect lead to the forced exit/expulsion of the Member State (in this case the UK) against its will.

The observation that under international Law a State who wants to remain in an organisation cannot be denied this right is correct but misses a significant contextual parameter in the case of Article 50. If a Member State is not absolutely certain that it desires to leave the EU, it should not trigger the process of withdrawal in the first place. Experimentation with Article 50 is certainly an attitude that the EU legislator wanted to discourage. Article 50 is a “special protocol” which ensures that the decision to proceed is unequivocal and thought through. In other words, the knowledge that Rubicon cannot be un-crossed (or at least not easily or without consequences) should inform the decision to cross it in the first place. This is clearly, in my view, the intended aim of Article 50 as it stems from the travaux préparatoires, the contextual, systemic and teleological interpretation of the provision and although I agree that it would be disproportionate to deny a MS the possibility of changing its mind, the recognition of the notification’s revocability should be accompanied by safeguards that do not undermine the role of Article 50 as a “special protocol” in the system of the Treaties.

Perhaps the Court considered that the UK’s ‘humbling’ experience during the Brexit negotiation provided a lesson to other Member States who may consider using this article without clear understanding of the consequences. Such a view is valid, but misses an important point. The ‘humbling’ experience of the United Kingdom was informed to a large extent by the signalling that the negotiating parties have been receiving from other important players, such as the markets. As I have argued elsewhere, the markets’ reaction has been informed so far by a belief or impression that the ‘clock is ticking’ –also an assumption of the UK Supreme Court in Miller­ (para 26)- in the sense that without a negotiated solution at the end of the two year period there was no safety net that could be deployed by the United Kingdom on its own. I believe that the interpretation of the Court might not guarantee a similar intensity of signalling from the markets (now knowing that there is the safety button) which could embolden Member States to play politics with Article 50 without consequences.

Revocability subject to Council’s Approval: Conditionalities and Safeguards 

Despite the CJEU’s ruling, the case for revocability subject to Council’s approval remains strong and is, in my view, the preferable interpretation for avoiding the metamorphosis of Article 50 into another negotiating device. I concur with Professor Weiler’s view that plausible legal narratives could be advanced in support of either of the two possible voting methods, namely unanimity and qualified majority. If the Council’s approval was subject to qualified majority voting then the concerns regarding the possibility of anyone of the remaining 27 Member States blocking the approval would not arise. Moreover, I argue that even if the Council’s approval required unanimity there are conceivable safeguards to ensure that MSs did not abuse their position as veto players.

First, I believe that the principle of sincere cooperation (Article 4 (3) TEU) would apply in this case.

Second, the will of the departing Member State can change truly and in an unequivocal manner only when fundamental parameters underlying its withdrawal decision have changed. This is the case for the UK. The revocation of the withdrawal decision will take place only when a large majority of the electorate will realise the futility of Brexit. Unfortunately, this cannot occur only with forecasts, which by and large are discarded as ‘scare-mongering’ but requires painful experience. In such a case I believe that the general principle of solidarity between Member States enshrined also in Article 222 (b) TFEU, applied directly (man-made disaster) or by analogy, would require the remaining 27 Member States to provide their assistance in the form of securing the revocation’s approval.


I believe that the CJEU’s ruling, unintentionally, has tied the Brexit gordian knot even tighter instead of unravelling it. Even if a new referendum, carried out prematurely, led to a marginal victory for Remain the Brexit proposition would still be lingering as a result of the CJEU’s ruling. Another party could promise before another general election to restore singlehandedly the ‘true’ will of the people (a scenario which would be compatible with the constitutional requirements of the UK).

In Euripides’ Iphigenia in Aulis the innocent heroine is led to believe that she is about to marry the most glorious of all the warriors of the ancient world, Achilles. She eagerly prepares for this splendid and happy occasion, despite warning messages suggesting that all is a ploy. Only when she arrives before the altar, reality reveals itself. The heroine according to the myth is saved by Goddess Artemis who, moved by Iphigenia’s ordeal, replaced Iphigenia, at the last minute, with a deer. I am afraid that that CJEU’s ruling is not a deus ex machina intervention for resolving Brexit. Unwittingly, it may contribute to the continuation of Iphigenia’s carefree preparations.

The author would like to thank Professor Alison Young, Professor Petros Mavroidis and Dr Vassilis Tzevelekos for their useful feedback. The usual disclaimer applies.

Dr Aris Georgopoulos, Assistant Professor in European and Public Law – Advocate, University of Nottingham, School of Law

(Suggested citation: A. Georgopoulos, ‘Revoking Article 50 TEU (C-621/18 Wightman and others): “Iphigenia Must Reach the Altar”’, U.K. Const. L. Blog (17th Dec. 2018) (available at

Advocate GeneralAs each day passes, a new window seems to be thrown open exposing fresh legal issues to be solved as the UK continues its journey towards its withdrawal from the European Union. It’s like opening an advent calendar for lawyers.

On Monday 10 December, the Court of Justice of the European Union in its Wightman ruling resolved the legal question of whether an EU Member State can revoke its Article 50 TEU notification of its intention to withdraw from the EU and do so unilaterally. The Court ruled that unilateral revocation is a permissible action of a sovereign EU state provided it occurs before a withdrawal agreement enters into force or before the expiry of the two-year period for negotiations (or an extended period).

On Tuesday 11 December, the former UK Prime Minister Sir John Major suggested that the right to revoke be invoked with immediate effect in order to ‘stop the clock’ and to give the UK government more time to sort out a Brexit process that has become chaotic with the Government pulling a vote on its negotiated Withdrawal Agreement to give the Prime Minister an opportunity to seek clarification from the EU on the so-called Irish ‘backstop’. However sensible a ‘pause’ in the process might seem, the issue is whether this is legally possible in terms of the Court’s Wightman ruling on revoking an Article 50 EU withdrawal notification.

With the entry into force of the Lisbon Treaty, the EU equipped itself with a procedure by which an EU Member State could leave the EU. And in the absence of any intervening event, as Lord Pannick put it in the Miller case, once a Member State pulls the Article 50 trigger and notifies the EU of its intention to leave, the bullet duly makes it way to the target of a withdrawal from the EU. In its Wightman ruling, the Court of Justice has offered up the possibility that the bullet can be reversed mid-flight and sent back from whence it came. As with the initial withdrawal notification, the revocation process must be in accordance with domestic constitutional requirements (on which see Phillipson and Young’s insightful post). But what if instead of being reversed, the bullet is simply left hanging in mid-air as might be implied by the former Prime Minister’s desire to stop time?

It is suggested here that while there is a facility within the Article 50 TEU process for negotiations to be continued and for the Article 50 time-frame to be extended – with the unanimous consent of the EU27 and the agreement of the UK – there is no pause button that can be pressed that could halt the Brexit bullet mid-flight.

It is worth recalling precisely what the CJEU said in Wightman (para. 74):

… the revocation of the notification of the intention to withdraw must, first, be submitted in writing to the European Council and, secondly, be unequivocal and unconditional, that is to say that 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.

It follows that revoking the UK’s Article 50 withdrawal notification in order to buy time to restart, reboot or redirect the UK’s Brexit negotiations is neither unequivocal – it would not be clear whether the UK intended to remain a Member State of the EU or ultimately to leave if the negotiations did not produce an acceptable outcome – nor would it bring the withdrawal procedure to an end if the intention was merely to pause the proceedings.

That the Court of Justice rejected the Council’s view that revocation required authorisation from the EU27 is based on the principle that EU membership is a voluntary commitment based on sovereign states’ willingness to share common values. But it is important to keep in mind that the EU law requirement that revocation is unequivocal and unconditional when combined with the domestic demands of a Member State’s own constitutional requirements are intended to be safeguards against the risk that a Member State would seek to revoke its withdrawal notification merely to buy itself more time or to game the negotiation process as the Council feared might happen. Indeed, Advocate General Campos Sánchez-Bordona in his Opinion is explicit that the control mechanism of domestic constitutional requirements is intended to avoid the risks of ‘tactical revocation’. Although the Court did not follow the recommendation of the Advocate General that revocation be subject to the principles of good faith and sincere cooperation, the Court’s insistence that revocation is unequivocal and unconditional is a stronger limit on the authority of a state to revoke an Article 50 withdrawal notification.

Although the position of the Court seems absolutely clear and would prevent a ‘pause’ other than through an extended negotiation period, there are evident uncertainties.

It is readily apparent that the Court assumes that if – through a democratic and constitutional process – a Member State changes its mind and decides to remain a Member State, then this is likely to be a once in a generation event. The Court makes no attempt to lay down any temporal limit as to when a Member State might change its mind again. It follows from the Court’s belief in the voluntary nature of EU membership that at some point in the future a Member State could again decide to relinquish the voluntary discipline of EU membership. At what point in time does a past revocation no longer need to satisfy the test of being ‘unequivocal’? Short time-frames – weeks or months between a revocation and a renewed notification of an intention to leave – would seem to cast doubt on the unequivocal nature of the earlier revocation. But if preceded by genuine domestic democratic and constitutional processes, who is to say?

Which leads to the more significant uncertainty, namely how is the Court’s requirements for revocation to be enforced and by whom and with what consequences?  This is perhaps where the apparently banal aspect of the revocation process – that the notification is submitted in writing to the European Council – has some significance. If the EU27 felt that a Member State was obviously making a ‘tactical’ revocation, it could adopt a decision refusing to accept the notification. The ‘revoking’ state would no doubt seek to bring proceedings before the Court of Justice challenging the European Council’s decision to refuse to accept the notification and it would then be for the Court to determine whether the European Council had correctly determined that a revocation was not ‘unequivocal and unconditional’. That would put the Court in a very challenging position. Accordingly, now that the Court has laid down the broad parameters of what EU law requires for a unilateral revocation of a withdrawal notification, the European Council should give serious consideration to the adoption of a Decision or Guidelines elaborating on what is meant by a revocation that is unequivocal and unconditional in order to facilitate judicial review. Of course, this could not have the effect of turning a unilateral right of revocation into an authorization process but it would create a mechanism for enforcing the requirements laid down by the Court.

More challenging is where the equivocal nature of a revocation is not apparent at the time it is made but only arises subsequently when a state which has revoked an earlier Article 50 notification submits a further notification of its intention to withdraw from the EU. This is perhaps where the Court’s wider messaging about the EU as a Union of shared values also has specific legal resonance in that such behaviour by a Member State might justify initiating the Article 7 TEU procedure which – at the limit – could lead to the suspension of that state’s rights under the Treaties because of the state’s serious and persistent breach of the values of the Union. This mechanism – the ‘nuclear option’ – is not however fit for this purposes.

These wider questions are perhaps not the ones that need a resolution today, tomorrow or in the remaining days of Advent. It is perhaps enough for today to agree with Sir John Major that the UK needs more time – Brexit Time – to sort out its position with regards to EU membership. Were there to be a change of Government in the weeks ahead, the idea of stopping the clock on Brexit could be appealing. However, in my view, pausing Brexit cannot legally be done in the terms laid down by the Court of Justice in its Wightman ruling on the revocation of an Article 50 withdrawal notification.

Kenneth Armstrong is Professor of European Law, University of Cambridge.

(Suggested citation: K. Armstrong, ‘The Advent of Brexit – Can It Be Paused?’, U.K. Const. L. Blog (12th Dec. 2018) (available at

The ECJ rendered today, 10 December 2018, its judgement in case C 621/18 Wightman in relation to the question whether the UK can unilaterally withdraw its Brexit notice of 29 March 2017.

There are three key take aways from that judgement:

1. The UK can unilaterally withdraw the Brexit notice prior to (i) the coming into force of the Withdrawal Agreement, or, if there is no Withdrawal Agreement concluded between the EU27 and the UK, (ii) prior to 30 March 2019, or, if there is an extension of the two year sunset period, (iii) prior to the end of such extension of the sunset period. The timing for a declaration for an Exit from Brexit is now clear; it had not yet been clear in the Advocate General Opinion of 4 December 2018.

2. If the UK declares such Exit from Brexit, after having gone through the required internal constitutional process in the UK, the UK would continue to be a Member State of the EU under terms that are unchanged as regards its status as a Member State. The Withdrawal procedure would just be brought to an end and the UK would not be “punished” but keep its current opt-outs etc.

3. Exit from Brexit would of course also leave the UK committed to the core principles of the EU, in particular

  • Ever Closer Union
  • Limiting its sovereign rights in ever wider fields
  • Primacy of EU law over the laws of the Member States and direct effect of EU law in the Member States
  • Application of the Charter of Fundamental Rights of the European Union
  • Elimination of the barriers which divide Europe, meaning free movement of persons.

The judgement gives the UK Parliament an option which was not available before. However, it is doubtful whether the UK Parliament would use that option on the basis of its current mandate, given that both the main parties campaigned on a manifesto to deliver Brexit. But the judgement could be used in conjunction with either an general election (which probably is less likely) or a second referendum, which may be a little more likely now than a week ago, but still fraught with constitutional, political and practical difficulty.

ActToday the Court of Justice of the European Union delivered its judgment in Wightman. This followed the opinion of Advocate General Campos Sánchez-Bordona, concluding that the UK may unilaterally revoke its notification of its intention to leave the EU. In a similar manner to the AG, the CJEU placed conditions on this unilateral revocation. A formal process would be needed to notify the European Council of the UK’s intention to revoke article 50. Such notice of revocation would have to be unequivocal and unconditional (para 74), and, importantly, ‘in accordance with the constitutional requirements of the Member State’, in this case, the UK, and following a ‘democratic process’ (para 66). It would also have to take place before the end of the Article 50 negotiation period, or any agreed extension, and before a Withdrawal Agreement between the exiting state and the EU had been ‘concluded’ – i.e. entered into force (para 73). In addition, the AG’s opinion was that any revocation would have to be in ‘good faith’ and in line with the requirement of ‘sincere cooperation’ between the Member State and the EU and. Further, although not required, it would be reasonable for the Member State to provide its reasons for revoking the Article 50 notification.

This raises an important question for UK constitutional lawyers:  what would be the constitutional requirements for the UK to lawfully notify the Council of its intention to revoke its Article 50 notification in order to remain in the EU? In particular, is AG Campos Sánchez-Bordona correct in his suggestion that ‘if the national constitutional requirements include, for example, prior parliamentary authorisation for the notification of the intention to withdraw from the European Union (as is the case in the United Kingdom, according to the Miller judgment), it is logical, in my view, that the revocation of that notification also requires parliamentary approval’ (para 145)?

This post will argue that primary legislation would be legally and constitutionally required in order to empower the Prime Minister to revoke Article 50. It will contend that the clear legal arguments in favour of this conclusion are reinforced by concerns of both political reality and arguments of constitutional legitimacy.

The need for legislation in UK law

Is the Advocate-General right to suggest that Miller means that legislation would be needed to empower the Prime Minister to revoke Article 50, in a similar manner to the legislation found to be required to empower the Prime Minister to trigger Article 50? Miller concluded that legislation was needed due to limits on the scope of prerogative powers and their lawful use. It found that triggering Article 50 was beyond the scope of the broad prerogative power to enter into and withdraw from Treaties as it would lead to a modification of domestic law, remove rights, and frustrate the purpose of the European Communities Act 1972 (‘ECA’) and the European Parliamentary Elections Act 2002.

Not all of the above limitations on the prerogative are applicable here. Unlike use of the prerogative to leave the EU, its use to revoke the UK’s Article 50 notification would not remove rights or alter domestic law. The UK remains a member of the EU throughout the negotiation period, and will lose this status only when it leaves the EU. As such, revoking Article 50 would merely maintain the status quo in terms of domestic law and the protection of rights. The rights, powers, liabilities, obligations, restrictions, remedies and procedures UK citizens currently enjoy through their membership of the EU would simply continue as Article 50 was revoked.

The principle that we do argue is applicable and engaged is that the prerogative may not be exercised in a way that frustrates the intention of Parliament as expressed in statute.  Critics of Miller might argue that the majority judgment did not rest on this principle but on the more controversial contentions that notifying Article 50 would result in the removal of a source of law in the UK (EU law) and hence precipitate a major constitutional change. However, those arguments may be regarded as flowing from the majority’s recognition of the unique constitutional importance of the ECA, which lead them to emphasise that rendering it a dead letter via the prerogative would actually remove a (de facto) source of law from the UK Constitution and thereby make a major change to the constitution.  However, we contend that even if one disagrees with those arguments as applied to the ECA, that does not affect the central argument we make in this blog.

That is because Miller did not invent the principle that the prerogative may not be exercised in a way that frustrates the intention of Parliament. Rather the majority judgment explicitly endorsed it as a pre-existing principle, flowing from the prior, unchallenged authorities of Fire Brigades Union (‘FBU’) and Laker Airways, which they cited with approval (para 51). Lord Browne Wilkinson summarised the basic principle in FBU:

it would be most surprising if, at the present day, prerogative powers could be validly exercised by the executive so as to frustrate the will of Parliament as expressed in a statute…

The majority in Miller affirmed this basic principle. ‘Ministers cannot frustrate the purpose of a statute or a statutory provision, for example by emptying it of content or preventing its effectual operation’ (para 51).  This principle follows logically from a basic aspect of parliamentary sovereignty – that Acts of Parliament rank higher than other sources of law, including the prerogative. Moreover, Article 1 of the Bill of Rights 1689 makes clear that the prerogative may not be used to ‘dispense with or suspend the execution of the laws’.  The dissenting judgments in Miller did not call the frustration principle into question; they merely considered that it did not apply, given their construction of the nature and purpose of the ECA. Thus our argument does not need to rely on any controversial aspect of the majority judgment in Miller and indeed would be the same even if Miller had never been decided. It simply applies the well-established frustration principle, which derives from FBU and Laker, and was expressly affirmed in Miller. 

What are the statutes whose purposes may be frustrated by revocation of Article 50? We suggest that there are two – the European Union (Notification of Withdrawal) Act 2017 and the European Union (Withdrawal) Act 2018 – and we take them in turn.

Frustration and the European Union (Notification of Withdrawal) Act 2017

Of the two Acts, it is less clear that the European Union (Notification of Withdrawal) Act would be frustrated. If we merely look at the title of the legislation, then its purpose may appear to be frustrated, given that it refers to the UK’s notification of its intention to withdraw. Moreover, section 1 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’. Whilst the purpose of this legislation was to empower the Prime Minister to notify the EU of the UK’s intention to leave in order to implement the wishes of the majority who voted in the 2015 referendum, the statute itself only grants a power. It does not require the Prime Minister to notify the European Union. The words ‘intention to withdraw’ also play an important role. These words mirror the requirements of Article 50(2) TEU. As the Advocate-General recognised, intentions may change. The decision of Parliament to give the Prime Minister power to notify the EU of the UK’s then intention to leave is not thwarted if the UK’s intention changes and the PM subsequently also notifies that changed intent.

Nor would the 2017 Act be rendered devoid of purpose by revocation. The legislation was used to trigger Article 50, negotiations have taken place, and a Withdrawal Agreement and Future Framework drawn up and agreed. Indeed, if the statute’s purpose had not been fulfilled then there would no need for the Prime Minister to revoke article 50; the UK would not need to revoke a notification of intention to withdraw if that notification had never been given to the EU under the power bestowed by the Act. So, whilst an argument may be made that this legislation would be frustrated, we do not consider it a particularly strong one. However, since we will argue that primary legislation is in any event needed due to the 2018 Withdrawal Act, our conclusion on this Act is not decisive for our overall argument.

Frustration and the European Union (Withdrawal) Act 2018

In relation to the European Union (Withdrawal) Act 2018 (EUWA), a much stronger argument can be made that using the prerogative to revoke Article 50 would frustrate its purposes. First, the whole purpose of the Act is to facilitate the UK’s actual exit (not its mere initial intention to exit) from the European Union. In our view, this would be frustrated were the UK to revoke Article 50 using the treaty prerogative. It could be argued that the 2018 Act merely provides evidence of an intention to leave the European Union, but that it is not a direct expression of that intention. But this is unpersuasive: the Act provides for the implementation of this intention, aiming to achieve certainty and stability by enabling existing EU law to continue to be applied in the UK as EU-derived law, unless and until this is amended by delegated or primary legislation. It also provides a means of remedying deficiencies in retained EU law which arise due to leaving the EU, or making provision to implement the Withdrawal Agreement prior to exit day.

However, an argument about the EUWA could be made that was similar to one advanced in Miller in relation to the European Communities Act 1972 (ECA). That statute was said by the Government side merely to provide a means of facilitating EU membership should the Government decide to join the then EEC, by allowing, inter alia, such EU rights and obligations as existed from ‘time to time’ to take effect in UK law. As such, it was argued that the ECA’s purpose would not be frustrated were the category of those rights and obligations to become an empty one (as would be the case when the EU Treaties ceased to apply to the UK).

Similarly it could be argued that the EUWA merely provides the means to implement the withdrawal of the UK from the EU should the UK Government finally decide to do so under the prerogative. However, this narrow approach to statutory purpose was emphatically rejected by the majority in Miller. It would be odd, therefore, if the courts were to prefer this more narrow reading of the EUWA having used a more purposive reading of the ECA in Miller. In a question of equal constitutional importance to that raised in Miller, there are strong constitutional arguments for adopting the same approach.  

This conclusion is reinforced when we examine the following provisions of the EUWA, which are currently in force (much of the Act has not yet been commenced). Sections 8 to 11 of the Act empower Ministers to enact delegated legislation when the Minister considers it appropriate to deal with defects that arise when the UK leaves the EU, or in order to implement the Withdrawal Agreement prior to exit day. These sections would be frustrated by revocation. It would no longer be the case that measures would be required to implement the Withdrawal Agreement, or to remedy defects in delegated or primary legislation arising from the UK’s withdrawal from the EU. Hence these provisions would be rendered devoid of purpose.

Sections 12(2), 12(4) and 12(6) of the Act modify the powers of the devolved legislatures and executives. Prior to the Act coming into force, the devolved legislatures were unable to enact legislation which contravened EU law. Nor could the devolved executives act in a manner which contravened EU law. Section 12 modifies this restriction, replacing it with a restriction not to act contrary to the provisions of section 12 of the EUWA. To revoke Article 50 unilaterally would frustrate the purposes of section 12, the aim of which is to allow powers repatriated from the EU to return to the devolved legislatures, enabling them to modify EU-derived law, unless Ministerial orders of the UK government have temporarily removed this power from the devolved legislatures in order to develop common frameworks.

Section 20 meanwhile defines ‘exit day’ while s 20(4) provides for a power to vary exit day by ministerial Order. This provision too would be rendered devoid of purpose were the UK to revoke; moreover it appears fairly clearly to provide evidence of parliamentary intention to exit, without which the whole notion of ‘exit day’, which runs through the provisions of the EUWA, would be meaningless.

Section 13 provides for the meaningful vote. Whether it would also be frustrated by revocation is perhaps more debatable. It might be argued that the narrow purposes of this section is only to provide for a process of parliamentary approval in relation to the Withdrawal Agreement and the Framework for the Future Relationship should the Government wish to ratify the former. In other words, it could be seen as merely a conditional provision, such that, were the Government to decide instead to revoke the Article 50 notice, the condition required for its application would not have come into play.

The contrary argument is that the aim of this provision is to provide Parliament with the opportunity to debate, and vote on, the Withdrawal Agreement and the Framework for the Future Relationship if they are agreed with the EU, as is the case now. The condition precedent for making section 13 “live” has thus been fulfilled and the Government has laid the relevant documents before the House, thus commencing the application of the process set out in that section. Revoking article 50, using the prerogative, would render both the Withdrawal Agreement and Future Framework otiose and hence frustrate the purpose of section 13, which is to enable Parliament to approve or disapprove those instruments, once agreed. (If the Government’s Withdrawal Agreement were to be approved by the meaningful vote, only for the Government later to revoke Article 50, then section 13 could be said to be frustrated after the fact because the approval of the Withdrawal Agreement that Parliament had bestowed would be rendered retrospectively nugatory).  More broadly, it could be said that the purpose of this provision is to enable Parliament to exert control over the decisive stage of the Brexit process; were the Government to revoke its Article 50 notice using the prerogative, that would seem to run counter to that broader aim.

An implied statutory power to revoke?

The above has assumed that the foreign affairs prerogative would be the domestic law power used to revoke Article 50. It could be argued instead that there is an implied statutory power to revoke, flowing from the 2017 Notification Act. Plainly there is no mention of any such power in the statute. Hence the argument would have to be that a power to notify under Article 50 also included the implied corollary power to withdraw which, the CJEU has now found, inheres in Article 50. Or it could be suggested that the power bestowed by the 2017 Act was to commence and conduct the negotiations with the EU that notifying Article 50 entails, and that this more general power included the power to withdraw the notice. This argument does not seem particularly strong, especially given our conclusion that the basic purpose of the Act was simply to empower the Prime Minister to notify the UK’s then intention to leave. To find an implied positive power to revoke in the face of that basic purpose would seem something a stretch, to say the least.

Law, politics and the constitution

The above arguments are reinforced by the following considerations of political and constitutional legitimacy. Given that a majority of those who took part in the referendum voted to leave the EU and Parliament has passed two Acts that allowed for the UK to withdraw from the EU, it would seem inconceivable that the Executive, acting alone through the prerogative, could legitimately make the decision to cancel that process via revocation.

Moreover, giving Parliament a full legislative role in the decision to revoke may be relevant to an EU law requirement. The A-G saw the need for adherence to national constitutional requirements as providing evidence for the EU law requirement that a Member State was not abusing its power to unilaterally revoke Article 50 by using this tactically to negotiate a better deal. To revoke Article 50 without legislation might not satisfy this evidential requirement, especially when coupled with the AG’s suggestion of reciprocity between the criteria for triggering and revoking Article 50. The decision of the CJEU appears to take this requirement further. To allow a Member State to revoke Article 50 without adhering to a democratic process ‘would be inconsistent with the Treaties’ purpose of creating an ever closer union among the peoples of Europe’ (para 67). Moreover,  ‘to force the withdrawal of a Member State which, having notified its intention to withdraw from the European Union in accordance with its constitutional requirements and following a democratic process, decides to revoke the notification of that intention through a democratic process’ would further undermine the EU’s value of respect for democracy (para 67). Use of the royal prerogative alone could surely not satisfy the requirements of ‘a democratic process’.

Our main legal conclusion is clear: should the decision be made to revoke the UK’s Article 50 notice, legislation would be required explicitly empowering the Prime Minister to do so. For the avoidance of any doubt, any such legislation would need to state that the power to revoke applied ‘notwithstanding any provision’ in the 2017 and 2018 Acts ‘or any other enactment’. At the very least, there is a strongly arguable case that legislation would be required: to seek to revoke without it would simply invite immediate litigation.

A further referendum?

Many argue that democratic legitimacy would require not just an Act of Parliament but also a second referendum to be held before a decision to revoke Article 50 could properly be made. Their argument may be reinforced by the decision of the CJEU, with its focus on the need for reciprocity and democratic legitimacy to uphold values of liberty and democracy in the EU – although it is clear that it is for the UK and not for the EU to determine the UK’s constitutional requirements.

Should the Commons refuse to approve the Withdrawal Agreement and Future Framework in the vote on the 11th December then a further motion is required under section 13(4)-(6) of the EUWA, taking note of how the Government proposes to proceed, in light of that rejection. However even were an amendment to be passed to that motion that called for a further referendum, that would not itself have any empowering legal force. Fresh legislation would still be needed to authorise the holding of any such referendum.

Were Parliament to pass such legislation, and were it to provide that remaining in the EU was to be one of the choices on the ballot paper, then that Act could provide the statutory authorisation for revocation that we have argued is constitutionally required. Indeed, to avoid arguments about the referendum’s legal status, it would make sense for the enabling Act to specify that, in the event that a majority voted ‘Remain’, the Prime Minister was required to revoke the Article 50 notice. Thus the referendum legislation itself could provide the necessary legal authority to the Prime Minister. It is hard if not impossible to see that such legislation could be passed and a referendum held before 29 March. Hence such a course would almost certainly require the UK to request an extension under Article 50(3), which would require the unanimous approval of the European Council.

The authors would like to thank Robert Craig for comments on an earlier version.

Gavin Phillipson is Professor of Law at Durham University. He is also currently a Parliamentary Academic Fellow in the Parliament and Constitution Centre in the House of Commons Library. The views above represent his personal view, which should not be taken as representing the views of the Library.

Alison L Young is the Sir David Williams Professor of Public Law, Robinson College, University of Cambridge.

(Suggested citation: G. Phillipson and A.L. Young, ‘Wightman: What Would Be the UK’s Constitutional Requirements to Revoke Article 50?’, U.K. Const. L. Blog (10th Dec. 2018) (available at

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