Devolution and the Sewel Convention

This note examines the devolution settlements in Scotland, Wales, and Northern Ireland, and the Sewel Convention—the constitutional convention whereby the Westminster Parliament will not normally legislate on devolved matters without the consent of the relevant devolved legislature. The focus falls heavily on the constitutional status of the Sewel Convention, its statutory codification, and the Supreme Court's treatment of it in R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5 and R (Miller) v The Prime Minister [2019] UKSC 41. You will also encounter the tension between parliamentary sovereignty, political conventions, and the evolving quasi-federal character of the UK constitution.

This week's material builds on earlier weeks: parliamentary sovereignty (Week 1), constitutional statutes (Week 2), the flexibility of constitutional form (Week 3), and prerogative power (Week 6). Devolution demonstrates that the orthodox Diceyan account of sovereignty remains doctrinally intact, yet is politically constrained in ways that scholars increasingly recognise as constitutionally significant.

Learning objectives: By the end of this note, you should be able to:

• Explain the reserved/devolved model in Scotland, Wales, and Northern Ireland.
• Analyse the codification of the Sewel Convention in statute.
• Critically assess the Supreme Court's treatment of convention in Miller (No 1).
• Evaluate whether devolution is compatible with orthodox parliamentary sovereignty.
• Situate UK devolution within comparative federal and quasi-federal models.

Devolution in the United Kingdom is the product of long-standing political demands for autonomy, particularly in Scotland, Wales, and Northern Ireland, combined with the Labour government's constitutional reform agenda in 1997–1999.

Scotland: The Act of Union 1707 created a unitary Parliament but preserved distinct Scottish institutions—the separate legal system, education, and the Church of Scotland. Nationalist sentiment grew in the 20th century, culminating in a failed 1979 referendum (which required 40% of the electorate to vote Yes, not just a majority of votes cast). The 1997 referendum, held shortly after Labour's landslide, saw clear support for a Scottish Parliament with tax-varying powers.

Wales: The historical relationship was more assimilationist. Wales was integrated into the English legal system by the Laws in Wales Acts 1535–1542. Nationalist sentiment was weaker than in Scotland, but cultural and linguistic distinctiveness supported devolution. The 1979 referendum was decisively rejected. In 1997, a narrow majority (50.3%) supported devolution, resulting in a much weaker settlement initially—legislative subordination rather than primary legislative power. Subsequent referendums (2011) approved the grant of primary law-making powers.

Northern Ireland: The Anglo-Irish Treaty 1921 and the Government of Ireland Act 1920 established a devolved Parliament at Stormont. That arrangement ended with direct rule in 1972 following the Troubles. The Belfast (Good Friday) Agreement 1998 established a power-sharing Assembly based on consociational principles. Devolution in Northern Ireland is conditional, suspended multiple times, and underpinned by international treaty obligations (the Agreement is lodged with the UN).

The devolution statutes: Scotland Act 1998, Government of Wales Act 1998 (since replaced by the Government of Wales Act 2006), and Northern Ireland Act 1998. These are 'constitutional statutes' within the Thoburn framework and cannot be impliedly repealed.

Devolution is often described as 'asymmetrical': the settlements differ in scope, powers, and institutional design. Unlike federalism, devolution is formally revocable by Westminster, though this is politically unthinkable in practice.

1. Reserved versus devolved powers

The Scotland Act 1998 operates on a reserved-powers model: the Scottish Parliament may legislate on any matter not explicitly reserved to Westminster. Schedule 5 lists reserved matters: constitutional matters, foreign affairs, defence, immigration, fiscal and monetary policy, and certain aspects of equality law. By contrast, the Government of Wales Act 2006 (as originally enacted) conferred specific subjects on the Assembly, but following the 2011 referendum and later amendments, Wales now also enjoys a reserved-powers model (Wales Act 2017).

Northern Ireland uses a tripartite model: excepted matters (reserved to Westminster indefinitely, e.g. defence), reserved matters (could be devolved later by Order in Council, e.g. policing—now devolved), and transferred matters (devolved from the outset).

*2. Legislative competence and vires challenges*

Devolved legislation is subordinate legislation in the formal sense: Acts of the Scottish Parliament (ASPs), Acts of the Northern Ireland Assembly, and Acts of Senedd Cymru (the Welsh Parliament) can be struck down by courts if they exceed competence. Section 29 Scotland Act 1998 provides that an Act is not law so far as outside competence. Competence is determined by whether the provision:

• Relates to a reserved matter;
• Is incompatible with Convention rights or EU law (prior to Brexit);
• Breaches other statutory restrictions.

Foundation (suitable for revision, less analytically demanding)

1. Explain the difference between reserved and devolved powers in the Scotland Act 1998.

1. What is the Sewel Convention, and why was it codified in statute?

Standard (typical exam questions)

1. 'The devolution settlements are incompatible with the doctrine of parliamentary sovereignty.' Discuss.

1. Critically assess the Supreme Court's treatment of the Sewel Convention in R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5.

Challenge (requires synthesis and original analysis)

1. 'Brexit has exposed devolution as a political illusion, not a constitutional reality. The doctrine of parliamentary sovereignty remains unaltered, and the courts have shown themselves unwilling to protect devolved autonomy.' Evaluate this claim with reference to statute, case law, and academic commentary.

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Guidance on Question 5 (Challenge)

This question invites critical evaluation of competing narratives: legal formalism (sovereignty intact) versus political constitutionalism (devolution transformed the constitution). You should:

• Discuss s 28(7) and formal sovereignty.
• Analyse the Sewel Convention's role and statutory codification.
• Evaluate Miller (No 1): did the Court fail to protect devolution?
• Examine Brexit: EU (Withdrawal Agreement) Act 2020, UK Internal Market Act 2020, and withheld consent.
• Engage with the 'permanence' provisions (Scotland Act 2016 s 1).
• Consider common law constitutionalism (AXA, Jackson): could courts impose limits?
• Assess whether 'illusion' is fair: has devolution constrained Westminster politically even if not legally?
• Compare federalism in Canada, Germany, or Spain.
• Conclude: sovereignty doctrinally unaltered, but constitution transformed politically; sustainability is questionable post-Brexit.

A strong answer will synthesise material from Weeks 1–7, particularly sovereignty, constitutional statutes, and the rule of law.

Essential (start here)

1. Aileen McHarg, 'Reforming the United Kingdom Constitution: Law, Convention, Soft Law' (2008) 71 MLR 853.

• Analysis of conventions and their codification; essential for understanding Sewel.

1. Alison Young, 'R (Miller) v Secretary of State for Exiting the European Union: Constitutional Conventions, Constitutional Statutes and Constitutional Principles' [2017] PL 131.

• Defends the Supreme Court's approach in Miller (No 1); argues conventions should remain non-justiciable.

1. Stephen Tierney, 'The Sewel Convention in the Brexit Supreme Court' (UK Const L Blog, 26 January 2017).

• Critical response to Miller (No 1); argues the Court was too deferential.

Advanced

1. Chris Himsworth and Christine O'Neill, Scotland's Constitution: Law and Practice (4th ed, Bloomsbury 2022).

• Authoritative textbook on Scots constitutional law and devolution.

1. Mark Elliott and Robert Thomas (eds), Public Law (4th ed, OUP 2020), ch 8.

• Excellent textbook chapter on devolution, integrating doctrine and theory.

1. Richard Rawlings, 'The Strange Reconstitution of Wales' [2021] PL 62.

• Wales-specific; analyses the shift from conferred to reserved powers.

1. Neil Walker, 'Beyond the Unitary Conception of the United Kingdom Constitution?' [2000] PL 384.

• Theoretical account of devolution and sovereignty; influential argument for quasi-federalism.

Comparative and theoretical

1. Reference re Secession of Quebec [1998] 2 SCR 217 (Supreme Court of Canada).

• Foundational comparative case on secession, federalism, and constitutional principles. Read the full judgment.

1. Jeffrey Goldsworthy, Parliamentary Sovereignty: Contemporary Debates (CUP 2010), ch 10.

• Defence of orthodox sovereignty against revisionist accounts; includes devolution.

1. Stephen Tierney, Constitutional Referendums: The Theory and Practice of Republican Deliberation (OUP 2012).

• Theoretical analysis of referendums and popular sovereignty; relevant to Scottish independence debates.

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Tip: For essays on devolution and Sewel, you must read Young and McHarg—they represent the leading opposing positions on justiciability. For questions on sovereignty, Goldsworthy is essential. For Scotland-specific analysis, Himsworth is unmatched.