Brexit: parliamentary scrutiny Contents

Chapter 6: Phase 3—ratification

Parliamentary approval for treaty ratification

63.Whatever agreements emerge from the withdrawal negotiations will take the form of treaties, requiring ratification by all parties.43 Treaties are ratified on behalf of the UK by the Government, acting under the Royal Prerogative. Under an undertaking originally given in 1924, and known as the Ponsonby Rule, successive governments allowed an opportunity for parliamentary scrutiny prior to ratification. This parliamentary scrutiny was ultimately codified in statutory form by Part 2 of the Constitutional Reform and Governance (CRAG) Act 2010, the key provisions of which are described in Box 2.

Box 2: Constitutional Reform and Governance Act 2010: provisions on scrutiny of treaties

  • Ministers must lay a treaty subject to the Act before both Houses of Parliament for 21 sitting days prior to ratification.
  • During this period, both Houses have the opportunity to pass a resolution that the treaty should not be ratified. If neither does so, the government can go ahead and ratify the treaty.
  • If either the Commons or the Lords votes against ratification, the government cannot immediately ratify the treaty, but must instead lay a statement giving the reasons why it wants to proceed with ratification.
  • If the Commons has voted against ratification, laying this statement triggers a further 21 sitting day period before ratification, during which time the Commons may again vote against ratification—potentially blocking a treaty indefinitely.
  • If the House of Lords votes against ratification, but the House of Commons does not, then a ministerial statement must be laid before Parliament explaining why the treaty should nevertheless be ratified, but the additional 21 sitting day period is not triggered. The House of Lords does not have the power to block ratification.

Sources: Constitutional Reform and Governance Act 2010, Part 2; House of Commons Library, Parliament’s new statutory role in ratifying treaties, Standard Note, SN/IA/5855, February 2011

64.Thus there is a statutory requirement that any treaties emerging from the negotiations should be laid before both Houses. It is of course impossible to forecast at this stage how parliamentarians, or the general public, will view the agreement, but given its importance, the Government will no doubt publish detailed explanatory material, to help inform the debates in both Houses (and beyond) that will certainly follow. Given that there may well be amendments to any motions to approve ratification, leading potentially to votes in one or both Houses, there would also be a strong case, should time allow, for giving Select Committees scrutinising Brexit in both Houses an opportunity to set out their views before any debates take place.

Withdrawal without an agreement

65.Although, as we noted in paragraph 38 above, there is no inherent reason why agreement on a withdrawal treaty should not be reached within the initial two years allowed under Article 50 TEU, the possibility that no agreement is reached within this time cannot be ruled out. In such a case, Article 50(3) states that “The Treaties shall cease to apply to the [withdrawing] State … unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period”44.

66.Lord Kerr told us that the underlying purpose of this provision was to provide “reassurance to sceptics that you were not tied to your oar for ever. If you want to get out with no agreement with the EU, if you want just to abrogate the treaty and repeal the Act, you can.”45 At the same time, he was clear that “nobody in their senses is arguing that that is what we should do”. We agree: a disorderly withdrawal from the EU, without any opportunity to plan the necessary legislative or treaty changes, or to make arrangements to ensure continuity in areas of vital mutual interest, such as security cooperation, would damage the UK and the EU in almost equal measure.


67.Any treaties arising out of the Brexit negotiations will engage the provisions of Part 2 of the Constitutional Reform and Governance Act 2010. Thus the two Houses will have an opportunity to pass resolutions that the treaties should not be ratified.

68. We would expect the Government, as well as laying the treaties before Parliament, to publish comprehensive explanatory material to inform public and parliamentary debate. It would be in the Government’s interest, should time allow, to give Select Committees scrutinising Brexit in both Houses an opportunity to set out their views before any debates and votes take place.

69.If, after two years of formal negotiations under Article 50 TEU, no agreement is reached either on the arrangements for withdrawal or on extending the deadline for negotiations, the UK will simply cease to be a member of the EU. Such an outcome cannot be ruled out, but would be highly damaging both to the UK and the EU.

43 If the treaties engage only areas currently subject to exclusive EU competence, the parties will be the UK and the EU. Ratification by the EU will require a simple majority in the European Parliament, and agreement by Qualified Majority Vote in the Council. If the treaties engage both EU and Member State competence, they will be ‘mixed agreements’, requiring consensus in the Council, and ratification by all 27 remaining Member States, in accordance with their domestic arrangements.

44 Article 50 (3), Treaty on European Union

45 Q 1. Lord Kerr’s views are reinforced by the explanatory notes on this article in the Treaty Establishing a Constitution for Europe: “The Praesidium considers that, since many hold that the right of withdrawal exists even in the absence of an explicit provision to that effect, withdrawal of a Member State from the Union cannot be made conditional upon the conclusion of a withdrawal agreement. Hence the provision that withdrawal will take effect in any event two years after notification. However, in order to encourage a withdrawal agreement between the Union and the State which is withdrawing, Article I-57 [now I-60] provides for the possibility of extending this period by common accord between the European Council and the Member State concerned.”

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