Royal Prerogative: Powers, Limits, and Oversight

Introduction

The Royal Prerogative is the set of residual executive powers of the Crown, now almost always exercised by ministers rather than the monarch. These powers arise from the common law, not from Acts of Parliament, and cover areas such as foreign affairs, defence, passports, honours, and senior appointments.

Although rooted in history, prerogative powers are not free from control. Parliament can remove or regulate them by statute, and the courts will review their use in appropriate cases. Two core limits shape the modern position: ministers must act within recognised prerogative categories and cannot use the prerogative to change domestic law, create new criminal offences, impose taxes, or override statutory schemes. Judicial review since the GCHQ case confirms that the source of power does not place it beyond the law.

This guide sets out the history, scope, legal limits, and practical oversight of the Royal Prerogative, with clear examples and steps you can apply in study and practice.

What You'll Learn

• What the Royal Prerogative is, who uses it, and where it comes from
• How prerogative powers have shifted from the monarch to ministers over time
• Common areas of use: foreign affairs, defence, appointments, honours, civil service, passports, and mercy
• How Acts of Parliament restrict or replace prerogative powers
• When and how courts review prerogative decisions, including limits and remedies
• Leading cases: Case of Proclamations, GCHQ, Fire Brigades Union, Miller (2017), and Miller/Cherry (2019)
• Practical steps to analyse a prerogative decision and prepare a judicial review
• Current reform debates on parliamentary scrutiny and transparency

Core Concepts

What Is the Royal Prerogative?

• Definition: The residual legal powers of the Crown recognised by the common law and exercised by ministers on the monarch’s behalf.
• No new prerogatives: New prerogative powers cannot be created by the executive; the categories are historically recognised and may shrink as Parliament legislates.
• Who acts: In practice, ministers make decisions (often formalised as Orders in Council). They are accountable to Parliament and subject to public law duties, including the Human Rights Act 1998.

Key rules in brief:

• Stay within recognised categories of prerogative.
• Do not change domestic law, impose taxes, or create offences using the prerogative.
• Respect statutory schemes; do not act in a way that frustrates Parliament’s choices.

Statute vs Prerogative

• Priority of statute: Where Parliament legislates, any overlapping prerogative is displaced to the extent of inconsistency. The executive cannot use the prerogative to bypass or undermine the statute.
• Filling gaps: If Parliament has not legislated, ministers may still act under a relevant prerogative, provided the action does not alter domestic law or remove statutory rights.
• Examples:
  • Treaties: Making treaties is a prerogative power, but the Constitutional Reform and Governance Act 2010 (CRAG 2010) requires most treaties to be laid before Parliament before ratification. Treaties do not change UK law without an Act.
  • Criminal injuries compensation: In Fire Brigades Union, ministers could not use the prerogative to replace a statutory scheme Parliament had chosen (even if not yet commenced).
  • Dissolution of Parliament: The Fixed-term Parliaments Act 2011 constrained prerogative dissolution. It was later repealed and replaced by the Dissolution and Calling of Parliament Act 2022, which restored a dissolution regime outside the 2011 framework.

Common Areas of Use

• Foreign affairs:

  • Recognition of states and governments
  • Making and ratifying treaties (subject to CRAG 2010 procedures)
  • Diplomatic relations

• Defence and national security:

  • Deployment of the armed forces and conduct of military operations
  • Intelligence and security decisions (often sensitive; courts may show caution in reviewing these, but they are not immune)

• Civil service and appointments:

  • Management of the civil service (now framed by CRAG 2010, Part 1)
  • Appointment of ministers, judges (within statutory processes), and senior public offices

• Honours and dignities:

  • Conferment of honours and peerages (subject to conventions and transparency initiatives)

• Passports:

  • Issue, refusal, and withdrawal of passports (reviewable in court, e.g. on fairness and rationality)

• Mercy:

  • The royal prerogative of mercy (free pardons and remission), though much sentencing and release is statutory

• Prorogation and dissolution:

  • Prorogation remains a prerogative act advised by the Prime Minister; it must not be used to frustrate Parliament’s ability to carry out its constitutional functions.
  • Dissolution arrangements changed in 2011 and again in 2022, illustrating how Parliament can reshape prerogative-related practices.

Judicial Review and Justiciability

• Review in principle: The leading GCHQ case confirms that prerogative decisions can be judicially reviewed. The court focuses on the subject matter, not the source of the power.
• Grounds of review: The familiar public law grounds apply—illegality (wrong purpose, fettering discretion, frustration of statute), irrationality, and procedural unfairness. Legitimate expectations and proportionality (where the Human Rights Act 1998 applies) may also be relevant.
• Limits and caution: Some subject areas, such as national security, war, and foreign policy, may involve evidence and judgments where courts proceed with care. However, important constitutional questions can still be justiciable, as shown in Miller (2017) and Miller/Cherry (2019).
• Remedies: Courts may grant declarations, quashing orders, and mandatory orders. In constitutional cases, a declaration may be the primary remedy. Where a decision is void (e.g., unlawful prorogation), the court may treat it as having no legal effect.

Key Examples or Case Studies

The Case of Proclamations (1611) 12 Co Rep 74

• Context: The King sought to change the law and impose controls by proclamation.
• Key point: The Crown has no prerogative except that allowed by the law; it cannot create offences or change law without Parliament.
• Use in practice: Start any analysis with this principle—no prerogative can be used to alter domestic law.

Council of Civil Service Unions v Minister for the Civil Service (GCHQ) [1985] AC 374

• Context: The Prime Minister used the prerogative to ban trade union membership at GCHQ on national security grounds.
• Key point: Prerogative decisions are reviewable. National security can justify limiting procedural fairness, but it must be assessed by the court.
• Use in practice: Apply standard judicial review grounds to prerogative actions; consider whether national security evidence is provided.

R v Secretary of State for the Home Department, ex p Fire Brigades Union [1995] 2 AC 513

• Context: The Home Secretary introduced a non-statutory compensation scheme using the prerogative rather than commencing a statutory scheme.
• Key point: The prerogative cannot be used to frustrate the will of Parliament. Where a statute sets out a scheme, ministers must not replace it through prerogative powers.
• Use in practice: Check for statutory frameworks in the same field. If present, the prerogative cannot lawfully cut across them.

R (Miller) v Secretary of State for Exiting the European Union [2017] UKSC 5

• Context: Whether the Government could trigger Article 50 TEU under the prerogative.
• Key point: The prerogative cannot be used to remove domestic rights created by Parliament. An Act of Parliament was required to authorise triggering Article 50.
• Use in practice: Ask whether the proposed prerogative act would affect domestic law or statutory rights. If yes, legislation is needed.

R (Miller) v The Prime Minister; Cherry v Advocate General for Scotland [2019] UKSC 41

• Context: Prorogation of Parliament at a politically sensitive time.
• Key point: Prorogation is justiciable. It is unlawful if it has the effect of frustrating or preventing Parliament from carrying out its constitutional functions without reasonable justification. The prorogation was void.
• Use in practice: Where a prerogative act impairs Parliament’s role, expect close scrutiny and a demand for cogent reasons.

R (Bancoult) v Secretary of State for Foreign and Commonwealth Affairs (No 2) [2008] UKHL 61

• Context: Orders in Council excluded the Chagossians from the British Indian Ocean Territory.
• Key point: Orders in Council made under the prerogative are reviewable. The majority upheld the orders on rationality grounds, illustrating both justiciability and judicial caution in sensitive policy areas.
• Use in practice: Even in foreign affairs, courts can examine legality and rationality, while allowing a margin for executive judgement.

Practical Applications

• Identify the power:
  • Is the decision based on a prerogative or a statute? Ask for the legal basis in writing.
  • If statute exists in the same field, read it closely to see if it displaces the prerogative.
• Check for statutory conflict:
  • Would using the prerogative undermine or frustrate a statutory scheme? If so, it is likely unlawful (Fire Brigades Union).
• Ask the “domestic law change” question:
  • Would the act alter rights or the legal position created by Parliament? If yes, legislation is required (Miller 2017).
• Assess justiciability:
  • Even in defence or foreign affairs, courts may review legality. National security claims must be supported by evidence, not slogans.
• Apply JR grounds:
  • Illegality: wrong purpose, irrelevant considerations, frustration of statute.
  • Irrationality: decisions outside the range of reasonable responses.
  • Procedural fairness: Was there a duty to consult? Any legitimate expectation? Were reasons provided?
  • Human rights: Consider HRA 1998 obligations and proportionality.
• Evidence and records:
  • Seek Cabinet Office guidance, policy papers, impact assessments, and any ministerial submissions. Clear records help or harm both sides.
• Parliamentary scrutiny:
  • Treaties: Follow CRAG 2010 laying and scrutiny processes; check for any resolutions or extensions.
  • Military action: Consider current conventions on parliamentary debate and votes, even if not legally binding.
  • Prorogation: Any decision must be supported by reasons that can be defended in court if challenged.
• Timing and procedure:
  • Judicial review must be brought promptly and within three months (unless a shorter limit applies). Issue a pre-action letter early.
• Remedies strategy:
  • Consider whether you seek a quashing order, a mandatory order, or a declaration (often suited to constitutional disputes).
• For government decision-makers:
  • Identify the precise prerogative relied on; record reasons; check for statutory limits; address equality and human rights duties; and plan for potential scrutiny by Parliament and the courts.

Summary Checklist

• Define the power: prerogative or statutory?
• Confirm that Parliament has not already provided a conflicting statutory scheme.
• Do not use the prerogative to change domestic law or remove statutory rights.
• Test for justiciability: subject matter may attract caution but is rarely immune.
• Apply standard JR grounds: illegality, irrationality, procedural unfairness, and legitimate expectation.
• Consider HRA 1998 duties; assess proportionality where relevant.
• For treaties, follow CRAG 2010 processes; remember no domestic change without an Act.
• For defence and foreign affairs, gather proper evidence if relying on national security.
• For prorogation or dissolution issues, assess constitutional effects on Parliament and the need for clear justification.
• Choose appropriate remedies and act promptly.

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