29.If Parliament is to approve the triggering of Article 50, it could do so either by means of legislation, or through a resolution (either of the Commons, or of both Houses). As we note above (see paragraph 16), the courts may rule later this year on whether legislation is legally required for the Government to trigger Article 50 in accordance with the UK’s constitutional requirements. Whatever the outcome of that court case, we consider that proceeding without parliamentary involvement, whether by means of a resolution or legislation, would be unwise. In this Chapter, we set out the advantages and disadvantages of the alternative mechanisms for parliamentary involvement.
30.One of the main benefits of using primary legislation is that it would provide legal certainty for the triggering of Article 50 (both in domestic courts and in the European Court of Justice). As one of our seminar participants noted: “If you are going to initiate [a] procedure that inevitably, unless further action is taken, will lead to the repeal of an Act of Parliament, the safest possible course is to introduce a Bill that enacts the authority to the Government to trigger Article 50.” Other participants agreed, with one stating that:
“lots of very serious things can be done by resolution of the House of Commons—Governments can be thrown out of office and similar matters. … But I am very taken by … [the] argument that you will have to put things beyond doubt. If it is possible to say that the authority of an Act is greater in the hierarchy than a resolution, then for safety first I would go for that”.
31.To this end, an Act could make clear that Parliament had given its authority to the Government to start a process that might well lead to existing legislation being repealed or substantially amended. Legislation of this nature would address any constitutional uncertainties that might otherwise arise (see for example paragraph 15) about the legitimacy of displacing existing primary legislation through the use of a prerogative power in this area.
32.Given the nature of the UK’s constitution, resting as it does on Acts of Parliament, convention and common law, the contents of any legislation would become part of the UK’s “constitutional requirements” for the purposes of Article 50. This means that Parliament could choose to set out requirements that would allow it to take control of the process by which Article 50 was to be triggered. For example, an Act could state that Parliament authorised the UK Government to trigger Article 50 if—and only if—the Government had first presented for parliamentary approval its proposal for the UK’s new relationship with the EU on the basis of which it intended to negotiate. We note in addition that if Parliament required the Government to meet certain prerequisites before Article 50 could be triggered, it would strengthen the Government’s position against those in the EU who argue that no negotiations, even informal, should take place before Article 50 has been invoked.
33.Legislation would require the assent of both Houses of Parliament, and would afford members of both Houses the opportunity to debate fully the issues at hand. The legislative process also provides a mechanism for reconciling differences between the two Houses (ping-pong), which would not be available should the Government seek a resolution of both Houses (see paragraph 42 below).
34.Legislation would clearly take some time to pass through both Houses of Parliament. The time taken, and the difficulty of a Bill’s passage, would depend to some extent on the content and purpose of the legislation. Yet, given how controversial the subject matter will be, keeping the scope of a Bill contained during its passage through Parliament might well present significant challenges to the business managers of both Houses. It is possible—even likely—that a narrow Bill focused on the issue of the triggering of Article 50 might find itself the focal point of wider debates about the role Parliament should play in the negotiation process more generally. Some may regard this as a good thing, others a disadvantage, but we note that the likely result is that it could be difficult for a Bill to pass through both Houses in a relatively short timeframe.
35.Political difficulties may arise should the devolved legislatures choose to vote on legislative consent motions relating to a Bill. We do not consider that a Bill relating to Article 50 would require legislative consent from the devolved nations—and particularly not if the Government put forward a tightly drawn Bill that focused solely on the issue of triggering Article 50. Triggering Article 50 is not a devolved matter nor does it alter devolved powers. There is also an argument that the Sewel convention would not apply in respect of any legislation relating to withdrawal from the European Union following a UK-wide referendum, since these circumstances are not ‘normal’ within the meaning of the convention. It is of course possible that the devolved legislatures would become involved in the passage of legislation by choosing to vote on legislative consent motions in any case. In that event, it is clear that the UK Parliament could legally pass such legislation even if legislative consent were withheld by any of the devolved legislatures. Nonetheless, this issue would not arise should parliamentary involvement take the form of a resolution, rather than legislation, and in either case the position taken by the devolved legislatures would be a political rather than a legal constraint on the UK Parliament.
36.A resolution stating Parliament’s approval for the triggering of Article 50 could be agreed by the Commons or both Houses far more swiftly than the passage of a Bill to the same effect. This would remove any uncertainty about Parliament’s acceptance of the referendum result, but would not necessarily provide a water-tight legal authority for triggering Article 50 against challenges in either the domestic or European courts. If the Government decide to proceed with triggering Article 50 as an exercise of the royal prerogative, however, then a resolution of one or both Houses may provide an appropriate vehicle for parliamentary involvement in the process.
37.Any resolution could be narrow in scope (simply granting parliamentary approval for the Government to trigger Article 50 at a time of their choosing), or address a range of broader questions—for example, setting out conditions for the triggering of Article 50 or laying down the mechanisms for parliamentary oversight of the withdrawal process. Any conditions set out in a resolution would not be legally binding on the Government, however difficult they might be for the Government to disregard in political terms.
38.In addition, a wide ranging resolution would be unwieldy to construct and relatively awkward to amend and debate. It is likely therefore that a resolution would be focused fairly narrowly on the triggering of Article 50. It would be harder for such a resolution to become a vehicle for a wider debate about parliamentary involvement in the negotiation process as a whole. A resolution would offer far less scope for amendment or debate than primary legislation.
39.If parliamentary involvement were to take the form of a resolution, then consideration would need to be given to what type of motion should be put forward, and to whether the assent of both Houses would be needed. The European Union Act 2011 may offer a useful precedent. It sets out two different procedures by which Parliament may authorise the Government to move forward with decisions at an EU level, short of Treaty changes that require a referendum. In certain specified cases, an Act of Parliament is required. In others, a motion is put before both Houses of Parliament, along with a draft of the decision to which assent is being sought, and both Houses are invited to pass the motion without amendment. In either case, the consent of both Houses is required.
40.There are other precedents for motions relating to the exercise of the royal prerogative that place parliamentary approval solely in the hands of the House of Commons. As we noted above, the approval of the House of Commons is required, by convention, before the deployment of the UK’s armed forces for active service. The process involves an approval motion being put before the House of Commons only, while an unamendable motion to “take note” of the issue is debated by the House of Lords. There is also the example offered by the Constitutional Reform and Governance Act 2010 in respect of ratifying treaties. Under that Act, the Government must lay a copy of a treaty before Parliament prior to ratification, and either House has 21 days to resolve that it should not be ratified. While a resolution of the House of Lords can be overridden by the Government, the Government cannot proceed in the event the House of Commons opposes ratification.
41.Given the political and constitutional significance of decisions relating to the UK’s membership of the EU, participants at our seminar generally felt that both Houses should be involved in approving the Government’s decision to move forward with Article 50. One participant noted that “it is much better that it should be by both Houses. Quite apart from anything else, one of the political issues around this is fixing Parliament collectively with responsibility for taking this process forward.”
42.It should be noted that if the assent of both Houses were sought by resolution, it would have to be by way of separate approval motions laid in each House. Such motions are always amendable. There is a risk that one or other House could amend its approval motion, leading to the two Houses passing differently worded resolutions. Unlike the process by which the two Houses pass primary legislation, there is no mechanism by which the two Houses can attempt to reconcile and agree a common wording for resolutions of this nature—although it would clearly be highly desirable for the main parties to reach an agreement on the precise wording of any such resolutions.
43.We consider it constitutionally appropriate that the assent of both Houses be sought for the triggering of Article 50.
44.An Act of Parliament would ensure that any constitutional uncertainties are avoided, and make certain that Parliament has the opportunity properly to debate the issues at hand and define in law the “constitutional requirements” that must be met before Article 50 is triggered. Resolutions would allow Parliament swiftly to demonstrate its position on the triggering of Article 50, while—in the case of a motion simply setting out that position—keeping that issue separate from wider debates about Parliament’s proper role in the negotiation process.
45.We consider that either mechanism would be a constitutionally appropriate means for the Government to secure parliamentary approval for the triggering of Article 50.
24 Although it has been argued that there is scope within of the European Communities Act 1972 for secondary legislation (in the form of an Order in Council) to be used, we consider that primary legislation would be more suitable in providing the advantages set out in this chapter.
25 Constitution Committee private seminar, July 2016
27 The Sewel Convention, also set out in the Scotland Act 2016, states that the UK Parliament will “not normally legislate with regard to devolved matters” without the consent of the relevant devolved legislature. Consent is also sought in respect of UK legislation affecting the extent of devolved powers (see Devolution Guidance Note 10: [accessed 3 August 2016]). Consent may therefore be required for amendments to the Scotland Act 1998, Northern Ireland Act 1998 and Government of Wales Act 2006 at the point of withdrawal from the EU, alongside the repeal or amendment of the European Communities Act 1972.
28 Devolved administrations are able to bring forward Legislative Consent Motions (LCMs) on matters that they consider to be within devolved competence, irrespective of whether the UK Government agrees that the matters require an LCM. A devolved administration may also advise their legislature not to support an LCM.
29 When we asked the Government to clarify whether the relevant section of the Scotland Act 2016 () was intended to give legal force to the Sewel Convention, the UK Government told us that the Convention remained a convention. See Constitution Committee, (6th Report, Session 2015–16; HL Paper 59), paras 37-41, and the Government response to that report: [accessed 9 September 2016]
31 Constitution Committee,
32 Constitutional Reform and Governance Act,
33 Constitution Committee private seminar, July 2016