In March, the Constitution Unit co-published a new report, Parliament and Brexit, in which some of the UK’s leading academics examine how parliament has managed Brexit to date, and how it might seek to handle the issue in future. Here, Nicola McEwen discusses how the Sewel convention, which regulates the relationship between the UK Parliament and its devolved counterparts, was put under strain by Brexit.

There are four legislatures in the UK, but only one of these is sovereign. The sovereignty of the Westminster parliament remains one of the most important principles of the UK constitution. Each of the devolution statutes made clear that conferral of law-making powers on the devolved institutions ‘does not affect the power of the Parliament of the United Kingdom to make laws’ for Scotland, Northern Ireland and Wales – including in areas of devolved competence. But Westminster’s parliamentary sovereignty is offset by the constitutional convention that it will not normally legislate in areas of devolved competence, or alter the competences of the devolved institutions, without their consent.

That convention, commonly known as the Sewel convention, has become an important principle underpinning UK devolution. It represents a tacit understanding that the devolved institutions, each of which was founded on popular consent in a referendum, have primary democratic and political authority over laws within their areas of competence.

From the outset, the scope of the Sewel convention was ambiguous. The UK and devolved governments have frequently disagreed on the extent to which UK legislation necessitates legislative consent from the devolved institutions. When tasked with determining its status following its inclusion in the Scotland Act 2016 and the Wales Act 2017, the Supreme Court in Miller I concluded that it remained a convention rather than a legal rule, therefore ‘the policing of its scope and the manner of its operation does not lie within the constitutional remit of the judiciary’. The Court thus left it to politicians and parliament to determine the operation and interpretation of the convention.

Analysis by the Institute for Government suggests that at least 202 Acts of Parliament have been subject to a legislative consent motion since 1999 in at least one of the devolved territories. For the most part, these have been uncontroversial and to the mutual convenience of each legislature. Withholding consent has been rare and does not amount to a constitutional veto. Rather, it represents a device inviting the UK Parliament to reconsider those elements of its legislation that affect devolved matters. It is for parliament – and the government of the day – to decide whether to heed the concerns of the devolved institutions, either by amending the legislation or removing the offending clauses. In a forthcoming overview of the Scottish constitution, Alan Page notes that a striking feature of successive UK governments has been their unwillingness to proceed with laws affecting devolved matters without the agreement of the devolved legislatures. This has given the devolved institutions some leverage in seeking to influence UK legislation. Equally striking, however, has been the extent to which, in the context of Brexit legislation in particular, the UK Parliament has been prepared to proceed despite consent being withheld.

In its legislative preparations for Brexit, the UK government had conceded that key elements of its EU (Withdrawal) Bill engaged the Sewel convention and it therefore sought due consent from the devolved legislatures. In a coordinated attempt to prevent what they regarded as a ‘power grab’ by the UK government, the devolved institutions in Scotland and Wales withheld their consent and instead introduced their own ‘continuity’ legislation. Both bills were referred to the UK Supreme Court to test whether they were beyond devolved competence before they could secure royal assent (the referral of the Welsh bill was later withdrawn following the Welsh Assembly’s consent for the UK bill). The Scottish continuity bill was rendered largely beyond competence by the protected status given to the 2018 EU (Withdrawal) Act. Despite this, the process of withholding consent, and the intense intergovernmental negotiations that followed, resulted in significant changes to the devolution clauses of the legislation.

The passing of the EU (Withdrawal) Act 2018 without the Scottish Parliament’s consent marked the first time that the convention had been set aside by the UK Parliament. It wouldn’t be the last. In the case of the EU (Withdrawal Agreement) Act, passed in January 2020 to give effect to the UK-EU Withdrawal Agreement in domestic law, all three devolved legislatures withheld their consent. As well as some opposition that strayed into the largely reserved matter of EU exit itself, the devolved institutions shared concerns that the legislation gave UK ministers powers to make decisions on devolved matters, and on the balance of devolved powers, without their agreement. The potential for the legislation to alter devolved competence, including via delegated powers, also raised concerns in the Lords – Crossbencher Lord Thomas of Cwmgiedd, former Lord Chief Justice of England and Wales, warned that this would set ‘a terrible precedent’. Defending the decision to proceed without the consent of any of the devolved legislatures, the Chancellor of the Duchy of Lancaster, Michael Gove, acknowledged that it was:

‘a significant decision and it is one that we have not taken lightly. However, it is in line with the Sewel convention… The Sewel convention — to which the government remain committed — states that the UK Parliament ‘will not normally legislate with regard to devolved matters without the consent’ of the relevant devolved legislatures. The circumstances of our departure from the EU, following the 2016 referendum, are not normal; they are unique.’

One of the problems with the convention as it stands is that the scope and application of the word ‘normally’ has never been determined. Deciding that circumstances are unique and ‘not normal’ only after consent has been sought and refused undermines the status and significance of the convention. With sufficient political will, it should be possible to remove some of these ambiguities. What constitutes the abnormal circumstances, under the terms of the convention, when consent need not be sought? In situations where it has been sought and withheld, what steps should the UK Parliament take to recognise the concerns of the devolved institutions without introducing a constitutional veto?

Numerous Brexit-related bills, as outlined in Jill Rutter and Joe Owen’s contribution to the Parliament and Brexit report, are now before parliament or in planning, and there are concerns about their impact on devolved competences. The practice of withholding consent is likely to produce diminishing returns for the devolved institutions if the UK Parliament proceeds without their consent. If that may seem like a bonus to some UK parliamentarians, they would be wise to consider the potential consequences of setting aside such a totemic symbol of devolution. To do so is unlikely to sustain trust and confidence in the capacity of the UK to respect the status of each of its legislatures – and of the territorial communities that they represent.

This post is a slightly edited copy of Nicola’s contribution to the latest joint report from the Unit and the UK in a Changing Europe. Entitled Parliament and Brexit, it contains analysis from some of the leading political scientists and legal experts in the UK. Full details of the report and the ability to download can be found here and the Unit blog will post several of its key pieces of analysis: you can see the whole series here.

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About the author

Nicola McEwen is Professor of Politics at the University of Edinburgh, and Co-Director of the Centre on Constitutional Change and a Senior Fellow at the UK in a Changing Europe.