1.1 The success of the leave vote in the Brexit referendum on 23 June 2016 raises novel political and legal questions which neither side of the referendum campaign would appear to have considered in any meaningful way. Two of the most crucial are who should trigger the Article 50 mechanism for withdrawal from the European Union, and how they should trigger it.
1.2 Article 50 of the Treaty on European Union (TEU) sets out the procedure for the withdrawal of a Member State from the EU. Article 50(1) requires the withdrawal of a Member State to “be in accordance with its own constitutional requirements”. Once triggered, a two year timeline starts to run at the end of which the relevant Member State must leave the EU, regardless of whether a formal withdrawal arrangement has been agreed (undoubtedly leaving the departing Member State with the weaker hand in any negotiations). The other Member States may decide, on a unanimous vote, to extend this period.
1.3 As a general rule, the conduct of foreign affairs, including the negotiation and conclusion of treaties, is a matter of Royal Prerogative (meaning that the decision rests with the Government, and here, most likely, with the Prime Minister). It has therefore been widely assumed that the Article 50 notice would be served by the Prime Minister at such time as he/she deems appropriate. However, various arguments have been made in recent days to the effect that the consent of Parliament is required before the Prime Minister may serve the Article 50 notice.
1.4 These arguments are explored in greater detail in the remainder of this bulletin. Like all aspects of the Brexit debate, it is difficult to say with certainty that any one interpretation is correct. However, it is clear that it would be possible to challenge, by way of judicial review, any decision by the Prime Minister to serve an Article 50 notice based solely on the exercise of the Royal Prerogative.
1.5 Although such a challenge may ultimately be unsuccessful, it underlines that there is a strong political argument to be made that Parliament should be involved in the decision to trigger Article 50 - not least to avoid adding the uncertainty of whether a valid Article 50 notice had been served to the burdens of Government, Parliament and the civil service at a time when the UK will be engaged in delicate and no doubt difficult negotiations as to the future relations of the UK with the EU.
2. Triggering Article 50 through use of the Royal Prerogative
2.1 As a general rule, the conduct of foreign affairs, including the negotiation and conclusion of treaties, is a matter of Royal Prerogative. Although there is no analysis of the underlying legal position, the assumption of the House of Commons, House of Lords and Government papers on the process of leaving the EU would appear to be that the Prime Minister would serve the Article 50 notice on the EU through the use of prerogative powers. There was no suggestion that the involvement of Parliament would be required.
2.2 This absence of consideration of the role of Parliament is perhaps understandable when one considers that Parliament typically has little involvement with treaties other than:
- A requirement under the Constitutional Reform and Governance Act 2010 for most treaties subject to ratification to be laid before Parliament for 21 days before the Government can ratify the treaty. (Parliament cannot however amend a treaty.)
- If a treaty requires domestic legislation to give effect to the relevant obligations (which any treaty replacing the European Treaties no doubt would), new legislation is usually put in place before the treaty is ratified.
2.3 In a Brexit scenario, it appears unlikely that either of these steps would take place before Article 50 is triggered, given the statements from various EU institutions and key Member States suggesting that Article 50 must be triggered before they will commence negotiations with the UK. Parliament therefore would have no involvement in the process prior to the service of the Article 50 notice.
3. Finding a Role for Parliament
3.1 Although foreign affairs is typically a matter of prerogative, the doctrine of parliamentary supremacy means that Parliament may abolish or modify the scope of Royal Prerogative. Where statute and prerogative deal with the same subject matter, the general principle is that the prerogative goes into abeyance (see Attorney General v De Keyser’s Royal Hotel  AC 508 where Lord Atkinson stated: “when such a statute, expressing the will and intention of the King and of the three estates of the realm, is passed, it abridges the Royal Prerogative while it is in force to this extent: that the Crown can only do the particular thing under and in accordance with the statutory provisions and that the prerogative power to do that thing is in abeyance.”)
3.2 The prerogative must also not be used to avoid the wishes of Parliament. This principle was set out in the House of Lords decision in R v Secretary of State for the Home Department ex parte Fire Brigades Union  2 AC 513. This concerned a criminal injuries compensation scheme which had been established in 1964 using powers contained in the Royal Prerogative. It was decided to put the scheme on statutory footing in the Criminal Justice Act 1988. The relevant sections were never brought into effect by the Secretary of State for the Home Department as required. Some years later, the Minister decided to make changes, using Royal Prerogative, to the original scheme which the Minister considered to be too expensive.
3.3 Following an application for judicial review of the Secretary of State for the Home Department’s actions, the House of Lords made the following findings:
- Where an Act of Parliament allows a Minister a discretion as to when its provisions should come into force, this does not permit the Minister to decide that the provisions should not take effect at all. It simply gives the Minister the freedom to determine when the time is right, perhaps in terms of the availability of resources and facilities, for effective implementation of the legislation in issue.
- In the period after a statute has been enacted and before it comes into effect, it is not lawful for the Minister to use the prerogative so as to obviate the need for the statute to be implemented. It is for Parliament to repeal the legislation and not the Government under the Royal Prerogative.
3.4 Based on the above, an argument has been made that as triggering Article 50 would cut across the European Communities Act 1972, leaving it effectively as a dead letter, parliamentary approval is required (Barber, Hickman and King1). The effect of the Article 50 notice in stripping British citizens of their rights to vote in the European Parliament pursuant to the European Parliamentary Elections Act 2002 is given as another example of how using the Royal Prerogative to trigger Article 50 would result in the prerogative being used to avoid the wishes of Parliament.
3.5 Several arguments have been made against this interpretation, including that triggering Article 50 does not amount to turning the European Communities Act into a dead letter (as delivering the Article 50 notice would not repeal the European Communities Act nor any other legislation), and that it is not clear that triggering Article 50 does frustrate Parliament’s intentions in enacting the European Communities Act (see for example: Elliott2).
3.6 Barber, Hickman and King’s interpretation also raises another interesting question as to whether, in considering whether the decision to withdraw falls squarely within the Government’s inherent prerogative powers to conduct foreign affairs, EU law should still be considered "foreign affairs" in the traditional sense, or whether, in particular in light of the rights which are granted to "EU citizens" including British citizens, it falls halfway between international and domestic law, granting rights which the executive branch should not be empowered to remove by way of Royal Prerogative.
3.7 An alternative view has been put forward by Tucker3, suggesting that section 2(2) of the European Communities Act 1972 (ECA) already provides a specific procedure for the invocation of Article 50. The provision states:
Subject to Schedule 2 to this Act, at any time after its passing Her Majesty may by Order in Council, and any designated Minister or department may by order, rules, regulations or scheme, make provision –
(a)for the purpose of … enabling any rights enjoyed or to be enjoyed by the United Kingdom under or by virtue of the Treaties to be exercised
3.8 Schedule 2 para. 2 of the ECA provides:
(1) … where a provision contained in any section of this Act confers power to make any order, rules, regulations or scheme (otherwise than by modification or extension of an existing power), the power shall be exercisable by statutory instrument.
Any statutory instrument containing an Order in Council or any order, rules, regulations or scheme made in the exercise of a power so conferred, if made without a draft having been approved by resolution of each House of Parliament, shall be subject to annulment in pursuance of a resolution of either House.
3.9 On this view, an Order in Council is required to trigger Article 50, in the form of a statutory instrument which would either need to be approved by both Houses of Parliament or can be annulled by either.
3.10 This view has the merit of seeking the response to a question posed by the interaction between European and domestic law in the legislation which has been enacted specifically to regulate such interaction. It also provides a way around the open question as to whether the UK’s engagement with the EU treaties remains a matter of pure international law subject to the Royal Prerogative.
3.11 One objection raised to this interpretation has been that the triggering of Article 50 would not appear to be a right which the UK enjoys by virtue of the European Treaties (Elliott4). This however seems doubtful; even assuming that Member States already had the right to withdraw from the EU prior to the introduction of Article 50 by the Lisbon Treaty, they would nonetheless have gained additional procedural rights by virtue of the introduction of the Article 50 mechanism. A second objection, based on the interpretation that section 2(2) does not apply where the UK is already empowered to act (by way of Royal Prerogative) is more problematic and brings back the question of whether Royal Prerogative is an appropriate tool in this situation.
3.12 A further suggestion has been put forward by Arvind, Stirton and Kirkham5, who suggest that the answer lies in section 2(1) EU Act 2011 which states:
(1)A treaty which amends or replaces TEU or TFEU is not to be ratified unless—
(a)a statement relating to the treaty was laid before Parliament in accordance with section 5,
(b)the treaty is approved by Act of Parliament, and
(c)the referendum condition or the exemption condition is met.
3.13 It is suggested that triggering Article 50, and therefore the ultimate deletion of the European Treaties, would be caught by section 2(1) of the EU Act and therefore the procedure set out above should be followed, requiring legislative consent. This argument would seem less compelling than the previous alternatives. Merely triggering Article 50 does not mean that an alternative treaty will be agreed to replace the European Treaties (although that will no doubt be the objective of the negotiating parties). Also, what is agreed may be so different from the European Treaties that it should be considered a completely new international treaty rather than a replacement for the existing European Treaties.
4. Fighting for a Role for Parliament
4.1 It is clear from the above that although there is little consensus on how Article 50 should be triggered, many consider that Parliament should be involved in the process. This raises the question as to what practically could be done if the Prime Minister were to seek to trigger Article 50 through the exercise of Royal Prerogative, without consulting Parliament.
4.2 Since the GCHQ case6, it has been clear that prerogative powers can be subject to judicial review. A decision to serve an Article 50 notice using Royal Prerogative could therefore be subject to challenge on the basis that it is ultra vires the executive’s powers, since Parliament’s authorisation is required.
4.3 Conversely, a question also arises as to whether it would be possible to bring judicial review proceedings challenging a failure to exercise the power to serve an Article 50 notice. If Article 50 can only be triggered with Parliament’s authorisation, that claim would clearly fail. If Article 50 can be triggered by Royal Prerogative alone, it would still seem highly unlikely that a court would compel the Government to serve the Article 50 notice given that under the European Union Referendum Act 2015 the referendum has no legally binding effect and the question of how the Government (and Parliament) respond to the referendum result involves a multitude of complex political questions that remain to be resolved (including when Article 50 should be triggered, what should replace the European Treaties and how and when that should be negotiated).