Professors Gavin Phillipson and Alison Young have argued on this blog that an Act of Parliament is needed to revoke article 50. An alternative view is that, while an Act may be desirable, it is not necessary. This is still an important issue because on Wednesday 27th of March 2019, 184 votes in the House of Commons were cast in favour of revoking article 50 before ‘exit day’ if no agreement had been reached, 293 votes were cast against, and 164 MPs abstained. By contrast, 400 MPs voted against ‘no deal’. Mathematically the question of revocation remains in play, because in an emergency a positive majority of the Commons may emerge. Because an Act takes longer than executive action, the question of the legal mechanism to revoke article 50 must be scrutinised.
Arguments that revocation of article 50 would frustrate statute
One possible starting point is that Advocate General Campos Sánchez-Bordona at  of his opinion in Wightman v Secretary of State for Exiting the EU (2018) C‑621/18 said that because triggering article 50 required Parliament’s authority, it was ‘logical, in [his] view, that the revocation of that notification also requires parliamentary approval’. This appears to have misunderstood R (Miller) v Secretary of State for Exiting the EU  UKSC 5, which decided that triggering article 50 risked depriving citizens of rights guaranteed by Acts of Parliament. Deprivation of rights requires a new Act. But revoking article 50 threatens nobody’s statutory rights: it protects them. On that basis alone an Act is not needed.
Professors Gavin Phillipson and Alison Young make a different, forceful argument that ‘using the prerogative to revoke Article 50 would frustrate [the] purposes’ of the European Union (Withdrawal) Act 2018. First, it is argued following Lord Browne-Wilkinson in R v Home Secretary, ex parte Fire Brigades Union  UKHL 3 that prerogative powers cannot ‘be validly exercised by the executive so as to frustrate the will of Parliament as expressed in a statute’. Second, Phillipson and Young say Miller (even if one disagrees with its result) has reaffirmed the principles set out in FBU (at  and ). Third, they say the ‘whole purpose of the Act is to facilitate the UK’s actual exit’ and it is unpersuasive to say the Act merely expresses an incomplete ‘intention’ to that effect. Fourth, they say this ‘conclusion is reinforced when we examine’ sections 8 to 12, which enable Ministers to write delegated legislation upon withdrawal for any ‘deficiency’, to implement the withdrawal agreement, and to change the restrictions of devolved legislatures to not act incompatibly with the Act rather than EU law. Fifth, the power of a Minister in section 20(4) to ‘amend the definition of “exit day”’ to ‘the day and time that the Treaties are to cease to apply to the United Kingdom’ would, they say, ‘be rendered devoid of purpose’ and ‘meaningless’.
Reasons that revocation of article 50 would not frustrate statute
The arguments of Professor Phillipson and Young must respectfully be rejected for at least five reasons. First, in the FBU case, on which Phillipson and Young rely heavily, the Home Secretary (Michael Howard) had a statutory duty to introduce a criminal injury compensation scheme, and it was this duty that would have been frustrated if the scheme was never introduced. According to Lord Browne-Wilkinson it was ‘of central importance’ that this duty was ‘itself in force’. But section 1 of the EUWA 2018 is not in force.
Second, even if section 1 of the EUWA 2018 were in force nobody has a duty in relation to exit day. Parliament gave ministers the power to ‘amend the definition of “exit day”’ to ‘the day and time that the Treaties are to cease to apply to the United Kingdom’. But if ‘the day and time’ never comes, Parliament said nothing further about it. This was wise because, as Lord Nicholls said in the FBU case, the ‘range unexpected happenings is infinite’, a ‘serious flaw… might come to light. An economic crisis might arise. The government might consider it was no longer practicable, or politic’ to continue.
Third, the language of the Act ensures that the UK can change its mind. If ‘exit day’ is never commenced the preparations and arrangements to be made under sections 8 to 12 never come into play because there is never any agreement by the House of Commons of ‘the withdrawal agreement’. Everything in the Act is ‘contingent and prospective’ (to adopt a phrase from insolvency law) upon a withdrawal agreement actually being agreed.
Fourth, the better view is that ‘Parliament has retained ultimate control over the UK’s withdrawal’, and this must include the possibility that ‘exit day’ could be indefinitely delayed. Section 13 says there must be ‘Parliamentary approval of the outcome of negotiations with the EU’. Any drafter of this legislation must have therefore envisaged that Parliament would simply say ‘no’. In any event, revocation would not mean there would never be exit day, because there is always the possibility that article 50 could be triggered again.
Fifth, upon revocation of article 50, exit day could simply be delayed pending a political decision to repeal the Act. In this situation, revocation could not be reasonably considered to frustrate the Act. Just as no referendum can rule the living forever from its grave, the keystone of our constitution is that no Parliament can bind a future Parliament.
Despite these reasons, it does not follow that an Act, though unnecessary, is undesirable. An Act of Parliament could be useful to remove the power of the executive with regard to the timetable of withdrawal and negotiations, and therefore the potential for its abuse. For this reason alone, the discussion of legislation, which Phillipson and Young have highlighted, is a valuable one.
Executive action to revoke article 50
If there is no question of frustration, this means that under the European Union (Notification of Withdrawal) Act 2017 section 1, the Prime Minister can revoke article 50. The popular view in the media appears correct that this is ‘a unilateral act that could be done in minutes by [the Prime Minister] via an email to Donald Tusk’. Section 1 is framed in the style of international law negotiations, which on the pathbreaking analysis of Sir Hersch Lauterpacht QC function like any ordinary contractual dealing. Indeed, the right to revoke an intention to negotiate for a deal (or an invitatio ad offerendum) is codified in the Vienna Convention on Treaties, article 68. Because pausing Brexit has become the majority will of the British public (a fact that seems to compound with demographic change) the orthodox legal position that the executive may revoke article 50 also appears politically sound.
(Suggested citation: E. McGaughey, ‘What Is Needed in Our Constitution to Revoke Article 50?’, U.K. Const. L. Blog (2nd Apr. 2019) (available at https://ukconstitutionallaw.org/))