Question: 'The devolution statutes purport to preserve parliamentary sovereignty, yet the Sewel Convention undermines it in practice. The Supreme Court in Miller (No 1) failed to reconcile law and politics.' Discuss.
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Introduction
This question invites analysis of the tension between formal sovereignty and practical constraint in the UK's devolution settlement. Section 28(7) Scotland Act 1998 preserves Westminster's unlimited legislative power, yet s 28(8) 'recognises' the Sewel Convention, which constrains that power politically. The Supreme Court in R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5 held the Convention non-justiciable, treating it as a political rule outside judicial remit. This essay argues that the devolution settlement does not undermine sovereignty doctrinally, but has transformed it politically, and that the Court's approach in Miller (No 1), while doctrinally defensible, left unresolved the constitutional status of entrenched conventions.
I. Parliamentary sovereignty and devolution: formal preservation
Dicey defined parliamentary sovereignty as the power to 'make or unmake any law whatever' with no legal limit (Dicey, Introduction to the Study of the Law of the Constitution, 10th ed, 1959). Section 28(7) Scotland Act 1998 explicitly preserves this: 'This section does not affect the power of the Parliament of the United Kingdom to make laws for Scotland.' Equivalent provisions exist for Wales and Northern Ireland. Legally, devolution is a species of delegation: Westminster confers powers but retains ultimate authority. It may repeal devolution statutes, legislate on devolved matters, or override devolved legislation.
This is consistent with Thoburn v Sunderland City Council [2002] EWHC 195 (Admin), where Laws LJ distinguished 'constitutional statutes' from ordinary statutes: constitutional statutes cannot be impliedly repealed, but may be expressly repealed. The devolution Acts are constitutional statutes (acknowledged in Imperial Tobacco Ltd v Lord Advocate [2012] UKSC 61 and AXA General Insurance Ltd v Lord Advocate [2011] UKSC 46). They are thus protected from inadvertent repeal but remain within Parliament's power to repeal expressly. Formally, sovereignty is intact.
II. The Sewel Convention: political constraint
The Sewel Convention provides that Westminster will not normally legislate on devolved matters without consent (Legislative Consent Motion). Articulated by Lord Sewel in 1998, it was a political assurance, not a legal rule. Its codification in the Scotland Act 2016 s 28(8) marked a significant development: 'But it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the consent of the Scottish Parliament.' Similar provisions exist in the Wales Act 2017 and for Northern Ireland.
The language is carefully crafted. 'Recognised' is declaratory, not imperative. 'Normally' implies exceptions. This preserves flexibility and avoids judiciability. Nonetheless, the Convention has binding political force. Routine breach would provoke constitutional crisis, undermine the Union, and likely trigger referendums.
Some scholars argue this undermines sovereignty in practice. McHarg contends that political constitutionalism has supplanted legal sovereignty: the normative foundation of Parliament's authority now rests on respecting devolved autonomy. Tierney argues sovereignty is functionally divided even if legally unified. On this view, sovereignty is a political claim, not merely a legal doctrine.
However, Goldsworthy and others respond that political constraints are not legal constraints. All constitutional actors operate under political limits (e.g., conventions of ministerial responsibility, royal assent). These do not negate sovereignty; they channel its exercise. The distinction between law and politics remains critical.
*III. Miller (No 1) and the non-justiciability of convention*
In Miller (No 1), the Supreme Court was asked whether the Sewel Convention required devolved consent before triggering Article 50. The Court unanimously held it did not, reasoning:
- Conventions are political, not legal, rules.
- The statutory codification did not render the Convention justiciable; the language was deliberately non-mandatory.
- Courts police legality, not political practice. Enforcing the Convention would require courts to determine what is 'normal'—a political judgment beyond judicial competence.
The Court stated: 'the policing of its scope and the manner of its operation does not lie within the constitutional remit of the judiciary, which is to protect the rule of law' [at 151].
This approach is doctrinally defensible. Conventions operate in the 'political constitution' (Griffith, 'The Political Constitution', 1979 MLR). Judicial enforcement risks constitutionalising political disagreement and undermining flexibility. As Young argues, conventions work precisely because they are not law: breach invites political sanctions (loss of confidence, electoral defeat), not judicial remedies.
Yet critics (McHarg, Tierney) argue the Court abdicated responsibility. The rule of law requires limits on power. Once a convention is in statute, even in declaratory form, courts should enforce procedural compliance (e.g., was consent sought? was refusal reasoned?). The Court's formalism prioritised sovereignty over devolution's democratic legitimacy.
IV. Did the Court fail to reconcile law and politics?
The quotation implies the Court failed. This is partly unfair, partly accurate.
Unfair: The Court's task was to apply law, not redesign the constitution. Parliament chose language ('recognised', 'normally') that preserved non-justiciability. Had Parliament intended legal enforceability, it could have drafted differently (e.g., 'The UK Parliament shall not legislate… without consent'). The Court respected legislative intent and constitutional roles.
Accurate: The Court's reasoning was formalistic. It treated the statutory codification as if it changed nothing, ignoring the political signal sent by codification: that the Convention matters constitutionally. The Court might have adopted a middle course: holding the Convention non-justiciable substantively, but requiring procedural compliance (consultation, reasons for proceeding without consent). This would respect the Convention without adjudicating 'normally'.
Moreover, the Court's approach sits uneasily with its expansive role elsewhere. In Miller (No 2) [2019] UKSC 41, the Court struck down prorogation as unlawful, effectively enforcing parliamentary sovereignty as a constitutional principle. If courts can protect parliamentary sovereignty against executive overreach, why not protect devolved democracy against majoritarian overreach? The asymmetry invites criticism.
V. Brexit as a stress test
Brexit demonstrated the Convention's fragility. The Scottish Parliament and Welsh Senedd withheld consent for the EU (Withdrawal Agreement) Act 2020 and UK Internal Market Act 2020. Westminster proceeded regardless, invoking the 'not normally' exception. The UK Government argued Brexit was a UK-wide constitutional measure, exceptional in nature. Critics argued this eviscerated the Convention.
The episode revealed that 'normally' is elastic. If Brexit—affecting devolved policy areas extensively—falls outside the norm, what remains within it? The Convention's normative force depends on restraint. Overuse of the exception risks rendering the Convention meaningless.
Conclusion
The devolution settlement formally preserves parliamentary sovereignty through provisions like s 28(7). The Sewel Convention constrains sovereignty politically but not legally. The Supreme Court in Miller (No 1) appropriately declined to judicialise the Convention, respecting the boundary between law and politics. However, the Court's formalism left unresolved the constitutional significance of codifying a convention in statute. Law and politics cannot be hermetically sealed; constitutional legitimacy depends on both. The devolution settlement has transformed the constitution in ways that formal sovereignty doctrine cannot fully capture. Whether this is sustainable—particularly in light of Brexit and renewed calls for Scottish independence—remains the central question for UK constitutional law.
(2,100 words)
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Tutorial feedback: This is a strong answer. You engaged with primary sources, distinguished legal and political constraints, and critically assessed Miller (No 1). To push toward a first-class answer: (1) engage more with comparative examples (e.g., Canada's Secession Reference); (2) discuss the 'permanence' provisions (Scotland Act 2016 s 1) and whether they alter the analysis; (3) interrogate whether the rule of law, as a common law constitutional principle (per Lord Hope in Jackson, AXA), might impose limits on repealing devolution unilaterally. These would add depth and demonstrate mastery of the Week 3–4 material on manner and form and the rule of law.