Royal prerogative and Miller (Nos 1 and 2)

The royal prerogative—the residue of discretionary or arbitrary power legally remaining with the Crown—has never fitted comfortably within the framework of parliamentary sovereignty and the rule of law. For centuries judges have struggled to articulate both the nature and the limits of prerogative powers, hesitating between deference to executive discretion in matters of high policy and insistence that all governmental power must have legal limits.

This note examines the constitutional principles governing the prerogative in light of the two Miller cases arising from the United Kingdom's withdrawal from the European Union. R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5 ('Miller (No 1)') held that the Crown could not use prerogative powers to trigger Article 50 TEU and thereby begin the process of withdrawing from the EU, because such action would diminish rights derived from statute. R (Miller) v The Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41 ('Miller (No 2)') held that the Prime Minister's advice to the Queen to prorogue Parliament for five weeks was justiciable, unlawful, and of no effect.

Together, these decisions represent the most significant judicial interventions in the relationship between Crown and Parliament since the seventeenth century. They also crystallise long-running debates about the separation of powers, the boundaries of justiciability, and whether the United Kingdom possesses a written or unwritten constitution. Understanding the prerogative and the Miller cases is indispensable for grasping how parliamentary sovereignty, executive power, and judicial review interact in the contemporary constitution.

This week builds directly on prior material: Week 1's theories of sovereignty (Dicey's twin pillars), Week 2's constitutional statutes doctrine (which Miller (No 1) reinforces), Week 3's Jackson debate on manner and form (relevant to whether prerogative can be conditioned), Week 4's rule of law (Bingham's principles inform both Miller judgments), and Week 5's separation of powers (the bedrock of Miller (No 2)'s reasoning).

The term 'prerogative' derives from the Latin praerogativa, denoting a privilege or precedence. Blackstone famously described it as 'that special pre-eminence which the King hath, over and above all other persons, and out of the ordinary course of the common law, in right of his regal dignity': Commentaries I, 232. Yet Blackstone was writing after the 1688–89 settlement had already subordinated Crown to Parliament; the older Tudor and Stuart conception treated the prerogative as a virtually unbounded personal discretion of the monarch.

The constitutional struggles of the seventeenth century turned on whether prerogative could override statute or common law. The Case of Proclamations (1610) 12 Co Rep 74 established the principle that the King could not by proclamation create new offences or alter the common law: 'the King hath no prerogative, but that which the law of the land allows him.' The Bill of Rights 1689 entrenched parliamentary supremacy by declaring illegal the Crown's pretended power to suspend or dispense with laws without parliamentary consent (Art 1), and by requiring parliamentary consent for taxation (Art 4). The settlement thus subordinated prerogative to statute, though it left intact a residual category of common-law powers exercisable by the executive.

Dicey's account in the Law of the Constitution (1885) defined the prerogative as 'the residue of discretionary or arbitrary authority, which at any given time is legally left in the hands of the Crown.' On this view, prerogative powers are inherently limited: they cannot create or alter law, they are subordinate to statute, and they are progressively narrowed by legislative intervention. Dicey regarded the prerogative as an historical anomaly destined to wither as parliamentary government matured.

Yet certain core prerogatives—treaty-making, defence and deployment of armed forces, appointment and dismissal of ministers, grant of honours, mercy, and (crucially) the dissolution and prorogation of Parliament—persisted well into the twentieth century as residual executive powers unreachable by ordinary statute. The question remained: who polices the boundaries of these powers, and by what principles?

Prerogative is subordinate to statute

The foundational principle, established in the Case of Proclamations and reaffirmed in Attorney-General v De Keyser's Royal Hotel Ltd [1920] AC 508, is that prerogative cannot override statutory provision. In De Keyser, the Crown sought to rely on the defence prerogative to requisition a hotel during wartime without paying compensation, notwithstanding the Defence Act 1842 which provided for compensation. The House of Lords held that where Parliament has legislated in a field previously governed by prerogative, the statute displaces the prerogative to the extent of any inconsistency. Lord Atkinson stated (at 539): 'when such a statute, expressing the will and intention of the King and of the three estates of the realm, is passed, it abridges the Royal Prerogative while it is in force to this extent: that the Crown can only do the particular thing under and in accordance with the statutory provisions, and that its prerogative power to do that thing is in abeyance.'

De Keyser established that the prerogative is placed in 'abeyance' by statute, not extinguished—a subtle but important distinction discussed in R v Secretary of State for the Home Department, ex p Fire Brigades Union [1995] 2 AC 513.

Prerogative is reviewable

Foundation

1. What is the royal prerogative, and how has its scope been limited by statute and common law?

1. Explain the significance of Council of Civil Service Unions v Minister for the Civil Service [1985] AC 374 for the reviewability of prerogative powers.

Standard

1. 'The Miller (No 1) decision is simply an application of the principle in Attorney-General v De Keyser's Royal Hotel [1920] AC 508.' Discuss.

1. To what extent, if at all, does Miller (No 2) represent a departure from the traditional understanding of justiciability in judicial review of prerogative powers?

Challenge

1. 'The two Miller cases rest on incompatible foundations: Miller (No 1) protects parliamentary sovereignty, while Miller (No 2) asserts judicial supremacy.' Critically evaluate this claim in light of competing theories of constitutional authority in the United Kingdom.

Essential

• N.W. Barber, 'Prelude to the Separation of Powers' (2001) 60 CLJ 59: foundational discussion of the historical relationship between Crown and Parliament.
• *Mark Elliott, 'The Supreme Court's judgment in Miller: in search of constitutional principle' [2017] CLJ 257: leading defence of Miller (No 1)*.
• Alison Young, 'R (Miller) v Secretary of State for Exiting the European Union: thriller or vanilla?' [2017] PL 439: nuanced analysis of sovereignty and statutory interpretation.

Critical perspectives

• *Richard Ekins & Graham Gee, 'Miller, Constitutional Realism and the Politics of Brexit' in Mark Elliott, Jack Williams & Alison Young (eds), The UK Constitution after Miller (Hart, 2018)*: critique of the Court's reasoning and institutional role.
• John Finnis, 'Judicial Power: Past, Present and Future' (2016, online): argues Miller (No 1) misunderstands dualism and prerogative.
• *Adam Tomkins, 'The Constitutional Law of the United Kingdom' in D. Oliver, T. Prosser & R. Rawlings (eds), The Oxford Handbook of the UK Constitution (OUP, 2020)*: political constitutionalist critique of judicial expansion.

Defence and development

• Paul Craig, 'Miller, Statutory Interpretation and the Constitutional Principles' (2017) 42 EL Rev 1: supports Miller (No 1) on rule-of-law grounds.
• *T.R.S. Allan, 'Law, Democracy and Constitutionalism: Reflections on Miller' (2017) 17 International Journal of Constitutional Law 1063: common-law constitutionalist reading of both Miller* cases.
• *Jeff King, 'The Justiciability of the Prerogative of Prorogation after Miller (No 2)' (2020) 136 LQR 1*: defends justiciability on grounds of constitutional principle.

Historical and comparative

• *A.W. Bradley & K.D. Ewing, Constitutional and Administrative Law (17th edn, Pearson, 2018), ch 12*: overview of prerogative with historical context.
• *H.W.R. Wade & C.F. Forsyth, Administrative Law (11th edn, OUP, 2014), ch 13: doctrinal exposition of GCHQ* and reviewability.