Thomas Fairclough: Article 50 and the Royal Prerogative


This piece seeks to address only one question: does Parliament or the Government have the power to decide to withdraw from the European Union in accordance with Article 50 TEU and through the notifying of the European Council of such a decision trigger the two year time limited formal withdrawal negotiations? Nick Barber, Tom Hickman, and Jeff King have argued valiantly that it will be Parliament who has to “pull the Article 50 trigger”. This piece will analyse their arguments and suggest that, contrary to their conclusions, it is the Government, under the Royal Prerogative, that has legal authority to start the Article 50 process.

The Article 50 Process

This piece assumes that it will be Article 50 that is used to begin the exiting process (as argued for here). It will also assume that the exiting process will begin; whilst there have been some suggestions that the United Kingdom will not try to exit the European Union I argue that this is unlikely as a matter of political fact (whilst legally, of course, the Government and Parliament could just ignore the referendum and carry on as normal).

Article 50 reads as follows:

  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….
  1. 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.

There are three things to note here: first, Article 50 is a one-way street, once it is invoked there is no procedural route for going back and, if an agreement is not reached and an extension of time not given, then the United Kingdom will exit the European Union two years from the date of notification of intention to exit. Second, there is no real process prescribed for the decision making process on behalf of the Member State; Article 50 simply states that such a decision be made by the Member State “…in accordance with its own constitutional requirements”. As such, the nature of this decision making process is purely a matter of domestic law. Third, Article 50 requires two things to start the leaving process: (i) a Member State has to decide to withdraw from the Union in accordance with its own constitutional requirements; and (ii) a Member State that so decides has to notify the European Council of such an intention.

It is trite to say that the referendum held on the 23rd of June 2016 was not a “decision” by the Member State; it was merely an opinion gathering exercise by Parliament. However, politically, it is hard to ignore. The question then is who gets to decide we are withdrawing from the Union and who then notifies the European Council?

Parliament or Government?

The Prerogative Power

It is for the United Kingdom to decide to withdraw from the European Union according to its own “constitutional requirements”. So what are the constitutional imperatives involved in treaty withdrawal? The United Kingdom has no codified constitution and so it is hard to know from first glance who or what gets to decide. Certainly the Government are of the opinion that it is for them to decide that the United Kingdom wishes to exit the European Union. Of course, the Government have not stated on what basis they have the authority to initiate the Article 50 process. However, it seems that they would presumably be utilising their power under the Royal Prerogative, which has always contained powers relating to foreign affairs. This has historically involved the making of treaties at international level. While the Ponsonby Convention (now on a statutory footing in Part 2 of the Constitutional Reform and Governance Act 2010) does require that treaties be laid before the Houses of Parliament for a period of 21 days before they are ratified, the ability of the Government ratify treaties remains a prerogative power, as does the power to amend or withdraw from treaties. Crucially, however, any obligations arising from international law treaties do not take effect at domestic level until Parliament chooses to incorporate all or part of the international law into the domestic sphere. To be clear, there is a formal separation between the international and national spheres; the Royal Prerogative allows the Government, on the Sovereign’s behalf, to conduct foreign affairs and enter into international treaties but these treaties only have any direct domestic application because Parliament (through an Act) intends it to be so.

On a simplistic analysis it would seem, then, that the Government (specifically, presumably, the Prime Minister) can, at the international level, use the Royal Prerogative power of foreign affairs to trigger the Article 50 process. This is because our constitutional arrangements leave it to the Government to conduct foreign affairs. In isolation, the exiting process would be a paradigm case of conducting international affairs through the prerogative power. In this way, the Government can activate Article 50 today, tomorrow, or in ten years.

Inter-play between Statute and Prerogative

Nonetheless, as Barber, Hickman, and King rightly point out the relationship between statute and the Royal Prerogative has long been contentious. As Lord Parmoor said inAttorney General v De Keyser’s Royal Hotel Ltd. [1920] AC 508 (HL):

When the power of the Executive…has been placed under Parliamentary control, and directly regulated by statute, the Executive no longer derives its authority from the Royal Prerogative of the Crown but from Parliament.

The precise scope of this principle is uncertain; some would say it is narrow, and if Parliament wishes to frustrate the Royal Prerogative it must speak clearly and not leave its intention to mere implication. On a wider view, as Barber, Hickman, and King argue, one could say that the “wider principle is that it is not open to Government to turn a statute into what is in substance a dead letter by exercise of the prerogative powers; and that it is not open to the Government to act in a way which cuts across the object and purpose of an existing statute”.

European Communities Act 1972 and Royal Prerogative

As noted above, Article 50 is a one-way street that, at the eclipse of two years without a deal to the contrary, releases the United Kingdom of its Treaty obligations. If it is the Government who activate Article 50 then they would be utilising the Royal Prerogative to take the United Kingdom out of the European Union despite the fact that the European Communities Act 1972 (“ECA”) expresses Parliament’s wish for EU law to apply domestically (section 2 ECA). In other words, this Act functions as an incorporating statute, bringing the United Kingdom’s international obligations into the domestic sphere with domestic effect. Barber, Hickman, and King argue “the obvious intention of the Act is to provide for the UK’s membership of the EU and for the EU Treaties to have effect at domestic law. The purpose of triggering Article 50 would be cut across the Act and render it nugatory”.

The argument goes that because withdrawal would render the 1972 Act hollow it would cut across Parliament’s intention in enacting the ECA. Since Parliamentary intention trumps prerogative power, the Royal Prerogative cannot be used to initiate the withdrawal process. Instead, it must be Parliament that does so.

Whilst incredibly well argued, this is not an argument that I agree with. The ECA was undoubtedly enacted to give effect to the United Kingdom’s international obligations vis-á-vis the European Union at the domestic level. However, regardless of such an Act, as a matter of international law the United Kingdom would already be bound at the international level. The ECA merely transposes these international obligation into the United Kingdom’s law in accordance with the constitution’s dualist approach to the domestic effect of international law. The use of the Royal Prerogative in initiating Article 50 will not repeal or modify the ECA. That is undoubtedly for Parliament to do. All it would do is alter the Treaties at the international level to remove the United Kingdom from its international obligations. This is entirely consistent with the will of Parliament as expressed in the ECA, which is to automatically give effect to European Union law as it applies to the United Kingdom at the domestic level. However, the relevant Treaties of the European Union govern European Union law and these Treaties are enlarged or reduced in scope, from the United Kingdom’s perspective at least, by the Government’s representative(s) acting under the Royal Prerogative. Therefore, the Royal Prerogative can be used to activate the Article 50 procedure.

Barber, Hickman, and King suggest that because section 2 ECA “provides that all such rights, powers, liabilities, obligations and restrictions” coming from the Treaties are part of the domestic law Article 50 could not be activated by the Executive because that would cause a loss of rights provided by European Union law. The idea here is that because Parliament provided for rights to be incorporated domestically under the ECA the Executive cannot use the Royal Prerogative to frustrate that purpose by initiating the withdrawal process (and therefore take rights away from citizens). This normative argument is based on a fallacy; the ECA provides that rights “from time to time arising” under the Treaties to apply domestically. Those rights can increase in scope (as has been the general trajectory of the European Union project) but, likewise, they can be restricted. There could be a Treaty change, for example, that abolishes the European Parliament. This would, on a strict analysis, only require assent from the United Kingdom via the Royal Prerogative and not from Parliament, despite the loss of a democratic “right”.

The authors may argue that a lowering of rights is acceptable within the current framework because that works within the European Union, whereas Article 50 would result in a withdrawal, which “cuts across the whole object and purpose of the 1972 Act, which is to make the UK part of the EU”. However, this is misguided. The 1972 Act was not designed to make the UK party to the European Union; it was rather to incorporate our international commitments into the domestic sphere. One way to demonstrate this is to reverse engineer the argument; if the Royal Prerogative had not been used to join the European Union but Parliament had still passed the ECA, the United Kingdom would not joined the European Union. Barber, Hickman and King seem to revert to potential arguments along these lines and dismiss any such contention as “a very formalistic analysis”. With respect, I contend that what they consider formalism is in fact the recognition of the important distinction between international legal obligations and the domestic legislation that may give effect to such. We are party to the European Union because of the Royal Prerogative, and we will leave the European Union because of the Royal Prerogative.


I have argued that (regrettably, from my point of view) it will be the Government, using the Royal Prerogative, who will decide if/when to trigger the Article 50 mechanism and take the United Kingdom out of the European Union. The ECA did not change this, default, position. It did not provide for the United Kingdom to become a signatory to the European Union, it merely replicated our international obligations in the domestic sphere. We negotiated and joined the European Union through the Royal Prerogative, and we will negotiate and leave the European Union through the same. That is not to say that Parliament has no role; indeed, I hope that Parliament makes its feelings well known to whoever the Prime Minister is at the relevant time, both in relation to when to trigger Article 50 and the content of the negotiations that follow thereafter. Nothing in this piece is to detract from that; all it seeks to do is locate each branch of the state in its proper setting.

Thomas Fairclough, AHRC PhD Candidate at Gonville and Caius College, Cambridge and Teaching Fellow in Public Law and Jurisprudence at University College London.


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