Sewel convention

Devolution to Scotland, Wales, and Northern Ireland does not alter the principle of parliamentary sovereignty. The UK parliament can legislate for all parts of the UK, including in relation to devolved policy areas, as well as to amend the powers of the devolved institutions themselves.

However, since 1999 Westminster has followed the Sewel convention, which holds that the UK parliament “will not normally legislate with regard to devolved matters except with the agreement of the devolved legislature,” ²² HM Government, Memorandum of Understanding and Supplementary Agreements Between the United Kingdom Government, the Scottish Ministers, the Welsh Ministers, and the Northern Ireland Executive Committee [The Memorandum of Understanding], 2013, www.assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/316157/MoU_between_the_ UK_and_the_Devolved_Administrations.pdf.  meaning the Scottish parliament, Senedd Cymru (Welsh parliament) and Northern Ireland assembly.

The convention applies when an Act of the UK parliament:

• changes the law in a devolved area of competence
• alters the legislative competence of a devolved legislature
• alters the executive competence of devolved ministers or departments.

How does the Sewel convention work in practice?

When the UK government plans to introduce a bill with provisions that fall within the scope of the Sewel convention, it is expected to consult with the devolved administrations early in the process, to ensure that devolved views are taken into account.

After a bill of this type is introduced in parliament, the devolved administrations publish a legislative consent memorandum, as required by the Standing Orders of the devolved legislatures in Cardiff, ²³ Standing Orders of the Senedd, January 2024, section 29.  Edinburgh ²⁴ Standing Orders of the Scottish Parliament, July 2024, chapter 9B.  and Belfast. ²⁵ Standing Orders of the Northern Ireland Assembly, March 2022, chapter 42A.

The legislative consent memorandum sets out the bill’s objectives, the reasons why consent is required, and usually indicates whether and why the devolved government believes consent should be given. Explanatory notes published alongside the bill at Westminster set out the UK government view as to which clauses of the bill fall within the scope of the Sewel convention.

Before a bill reaches its final amending stage in the UK parliament, the devolved legislatures vote on a legislative consent motion to either grant or withhold consent for the bill, in part or in full. If consent is not granted, the UK parliament can decide whether to amend the bill to meet the devolved concerns, or to pass the legislation as it stands.

Determining whether a bill’s provisions require legislative consent is not always straightforward, and has been a source of disagreement between the UK Government and devolved administrations on a number of occasions, typically where the devolved governments take a broader view of how legislation affects devolved matters. For instance, in 2023 the Senedd voted to withhold consent from the Genetic Technology (Precision Breeding) Bill but the UK government held that this was a reserved matter and pressed ahead with the bill.

There have also been disagreements between the devolved administrations and their respective legislatures. For example, in 2023 the Scottish parliament’s presiding officer blocked the Scottish government’s legislative consent motion for the Illegal Migration Bill on the grounds that it related to reserved matters and fell outside of devolved competence. 

Committees of the Scottish and Welsh parliaments have also sometimes criticised devolved ministers for allowing the UK government to legislate on devolved matters, which reduces the scope for scrutiny at the devolved level.

What happens when devolved consent is withheld?

As a constitutional convention, Sewel and the legislative consent process are not legally binding. Although put into law in the Scotland Act 2016 and the Wales Act 2017, these acts only ‘recognise’ the existence of the convention; they do not limit the power of the UK parliament to legislate on all matters for all parts of the UK. 

In 2017 the Supreme Court ruled that since Sewel remains a convention, “policing the scope and manner of its operation does not lie within the constitutional remit of the judiciary.” ²⁶ R (Miller) v Secretary of State for Exiting the European Union  The devolved governments therefore cannot turn to the courts to enforce Sewel, nor to resolve disputes over whether a bill’s provisions engage the convention

As a consequence, the UK parliament is able to pass bills without devolved consent, even when the UK government accepts that the legislation in question falls within the scope of the Sewel convention.

How often has the Sewel convention been used?

Legislative consent motions were voted on in at least one of the devolved legislatures in relation to approximately 220 acts of parliament in the first 25 years of devolution, from 1999 to July 2024. The total number of legislative consent motions stands at over 400, because many bills require consent from more than one devolved legislature, some bills are voted on more than once, and some legislative consent motions are voted on for bills that never reach the statute book.

In a large majority of cases, the Sewel convention has operated without controversy. In total, the Scottish parliament has given consent to 198 acts since 1999, and withheld consent only 15 times. Senedd Cymru has consented to 90 acts and said no on 20 occasions. For the Northern Ireland Assembly, which has undergone several periods of suspension, the figures are 85 and 2. 

In total, this means that consent has only been denied by at least one of the devolved governments, in part or in full, from 28 acts. ²⁸ From 1999 to June 2024.  However it is notable that 19 of these cases occurred within the 2019-24 parliament. 

On a number of these occasions, the legislation was amended at Westminster to account for devolved concerns following the vote to withhold consent. In other cases, UK ministers opted to proceed in the absence of consent – sometimes due to disagreement over whether the legislation did in fact relate to devolved matters, and sometimes despite UK ministers agreeing that it did.

Did Brexit require devolved consent?

International relations, including relations with the EU, are reserved matters under the devolution statutes. This means that they are in the exclusive competence of the UK government.

However, much of the legislation needed to implement Brexit related to devolved matters and amended the powers of the devolved institutions. Therefore, devolved consent under the Sewel convention was sought, but several bills relating to Brexit were passed without consent.

The EU Withdrawal Act 2018 was the first piece of Brexit legislation recognised by the UK government to fall within the scope of the Sewel convention. The bill was opposed in its original form by both the Scottish and Welsh governments. Following concessions by the UK government, consent was given by the Senedd. However, the Scottish parliament voted to withhold consent. The legislation was enacted anyway, making this the first time Westminster had legislated without Scottish consent after having recognised that consent should be sought.

The UK government also accepted that the Sewel convention applied to the European Union (Withdrawal Agreement) Bill. In January 2020, all three devolved legislatures denied consent to the bill, but the UK parliament passed the legislation regardless. The Scottish parliament and Senedd also voted to withhold consent from other Brexit-related legislation such as the UK Internal Market Bill. 

What proposals have been made for reform of Sewel 

There have been various proposals – including by the Gordon Brown Commission in 2020 and the Independent Commission on the Constitutional Future of Wales in 2024 – to strengthen the status of Sewel, by making it more difficult for Westminster to proceed with legislation without consent. ³¹ Labour Party, ‘A New Britain: Renewing our Democracy and Rebuilding our Economy’, December 2022, p. 103; The Independent Commission on the Constitutional Future of Wales, ‘Final Report: January 2024’, The Independent Commission on the Constitutional Future of Wales, 17 January 2024, retrieved 22 January 2024, www.gov.wales/sites/default/files/publications/2024-01/independent-commission-on-the-constitutional-future-of-wales-final-report.pdf, p. 58; Plaid Cymru, ‘Manifesto: The Party of Wales’, June 2024, p. 44; Scottish National Party, ‘A future made in Scotland: SNP 2024 Manifesto’, June 2024, p. 25.  The Institute for Government has previously recommended reforms to parliamentary procedure and government practice to enhance the status of Sewel without preventing the UK parliament from legislating without consent.  In its 2024 manifesto, the Labour Party did not commit to any of these reforms but did promise to strengthen Sewel by “setting out a new memorandum of understanding outlining how the nations will work together for the common good.” ³² Labour Party, ‘Change: Labour Party Manifesto 2024’, June 2024, p. 109.