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The Crown and Prerogative Powers for SQE1

Part of our SQE1 Constitutional and Administrative Law guide → View the full SQE1 Constitutional and Administrative Law guide

13 May 2026

Prerogative powers are residual powers of the Crown exercised by government ministers for matters such as foreign policy, defence and treaty-making. Understanding which prerogative powers are reviewable and the limits on judicial control is essential for SQE1.

The Crown and Prerogative Powers for SQE1

Constitutional & Administrative Law > The Crown and Prerogative Powers

Prerogative powers are residual powers of the Crown — powers that historically belonged to the monarch and are now exercised by government ministers. These include foreign policy, treaty-making, deployment of armed forces, and appointment of senior officials. SQE1 tests whether you understand which prerogative powers are subject to judicial control and when courts can review their exercise.

What Are Prerogative Powers in SQE1?

Candidates frequently lose marks by assuming all prerogative powers are immune from judicial review — in fact, the test is justiciability. Prerogative powers are powers that remain with the Crown outside the scope of parliamentary legislation. They are treated as part of the common law, comprising those powers and privileges that were historically exercised by the monarch and have survived into the modern era.

Key prerogative powers include:

  • Power to enter into treaties and international agreements
  • Power to deploy the armed forces
  • Power to appoint and dismiss ministers
  • Power to grant honours and titles
  • Power to regulate the Civil Service
  • Power to issue Royal Charters
  • Power to grant pardons and mercy

The Crown acts through ministers — the monarch no longer exercises these powers personally. Ministers exercise them in the name of the Crown (technically under the advice of the Privy Council).

Key Principles for SQE1

  • Prerogative powers are part of the common law: they are not statutory but derive from historical practice and are recognised by the courts. They are residual — Parliament can curtail or abolish them through legislation.

  • Justiciability of prerogative powers: following R v Secretary of State for Foreign Affairs, ex parte Everett [1989] and R (Bancoult) v Secretary of State for Foreign Affairs [2008], courts can review prerogative powers IF they affect legal rights or obligations. The key test is whether the matter is "justiciable" — suitable for judicial determination. Some matters (such as foreign policy decisions) are not justiciable; others (such as exercise of a prerogative power that impacts property rights) are. This test is also crucial for understanding how the rule of law applies to executive action, and how judicial review operates as a check on unlimited executive power.

  • Foreign policy and national security: are generally not justiciable. Courts will not review decisions about treaty negotiation, diplomatic relations, or military operations. In Council of Civil Service Unions v Minister for the Civil Service [1985], the House of Lords stated that matters of national security are not reviewable even though they involve exercise of a prerogative power.

  • Conditions and scope: prerogative powers can be exercised subject to conditions, and those conditions are reviewable. For example, if a statute requires certain procedures for granting a prerogative power, the courts can review compliance with those procedures.

  • Parliamentary control: Parliament can curtail or abolish prerogative powers by legislation. Many historic prerogative powers have been replaced by statutory frameworks.

  • Ministerial accountability: while courts may not review certain prerogative powers (particularly foreign policy), ministers remain accountable to Parliament. Parliament can question ministers about their exercise of prerogative powers and can legislate to restrict those powers.

  • Excluded matters: following CCSU v Minister for the Civil Service, matters relating to national security, defence, and foreign relations are less likely to be reviewable. However, even in these areas, procedural fairness requirements may apply.

Exam tip

The key SQE1 trap is assuming all prerogative powers are non-reviewable. The test is justiciability — is this a matter the courts can properly determine? Foreign policy is generally non-justiciable; decisions affecting individual rights or property are generally justiciable. If the question asks whether courts can review a particular prerogative decision, carefully consider whether the matter is one courts typically review.

How This Appears in SQE1 Questions

SQE1 questions typically present a scenario where the Crown (via a minister) has exercised a prerogative power and someone seeks judicial review. This is a classic SQE1 trap where understanding justiciability is essential. The question tests whether you correctly identify the power as prerogative, determine whether it is justiciable, and identify the appropriate grounds for challenge (if any).

Example scenario: The Foreign Secretary negotiates a treaty on behalf of the Crown and signs it without parliamentary approval. A pressure group challenges the treaty. Can the courts review the decision to negotiate and sign the treaty? The answer is likely no — foreign policy is non-justiciable. However, if the Foreign Secretary failed to follow statutory procedures required for treaty ratification, courts might review that procedural issue.

This is a classic SQE1 trap: distinguishing between the substance of a foreign policy decision (not reviewable) and procedural compliance (reviewable). Stay alert to this distinction.

Common Mistakes Students Make

  • Assuming all prerogative powers are non-reviewable — justiciability depends on the nature of the power and matter
  • Confusing prerogative powers with statutory powers — prerogative powers are part of common law; statutory powers are granted by Parliament
  • Forgetting that ministers exercise prerogative powers in the name of the Crown — understanding the Crown's role is important for identifying these powers
  • Overstating the protection given to prerogative powers — while some are non-justiciable, others (such as those affecting property or individual rights) are reviewable
  • Missing that Parliament can abolish or restrict prerogative powers — Parliament's sovereignty means it can legislate to curtail executive prerogatives
  • Assuming parliamentary accountability is insufficient — while courts may not review certain prerogatives, parliamentary scrutiny provides a check on their exercise

Quick Summary

  • Prerogative powers are residual powers of the Crown exercised by ministers
  • The key test is justiciability — can courts properly determine this matter?
  • Foreign policy, national security and defence are generally non-justiciable
  • Prerogative powers affecting legal rights or property are generally reviewable
  • Parliament can curtail or abolish prerogative powers through legislation
  • Ministers remain accountable to Parliament even if courts cannot review certain prerogative decisions
  • Courts can examine whether conditions and procedures for exercising prerogative powers have been met

Want to test this now? Try a few SQE1-style questions below before moving on.

Test Yourself

Test yourself

Quick check questions based on this article.

Question 1

Scenario

A minister responsible for immigration has issued guidance under which certain categories of foreign nationals are to be refused entry to the United Kingdom on grounds of national security. The guidance does not rely on any statutory provision but is stated to be issued under the royal prerogative relating to control of borders. A foreign national, who holds a valid visa issued under the Immigration Act 1971, has been refused entry at a port of arrival on the basis of this guidance. The foreign national's solicitor has confirmed that the visa was obtained lawfully and that none of the statutory grounds for refusal under the Immigration Act 1971 apply. The guidance was not laid before Parliament prior to its issue. The Home Office has received several letters from a charity questioning the humanitarian impact of the guidance, but these have not been formally considered. A senior civil servant involved in drafting the guidance had previously worked for a defence think-tank, though there is no suggestion of any conflict of interest. The foreign national has filed an application for judicial review challenging the refusal of entry. The government contends that the prerogative power over border control supplements the statutory regime and allows additional grounds for refusal. The foreign national argues that where Parliament has legislated on a subject, the prerogative cannot be used to contradict or go beyond the statutory framework. The case has attracted significant media attention.

Which of the following best describes the likely outcome of the judicial review application?

Question 2

Scenario

A solicitor is advising a client who has been asked to appear as a witness before a parliamentary select committee investigating government procurement practices. The client is a director of a company that has a contract with a government department. The client is concerned that some of the questions may require her to disclose commercially sensitive information. The select committee has issued a formal summons requiring the client's attendance. The solicitor has researched the matter and found that the government has argued in correspondence with the committee that certain documents relating to the procurement are protected by the royal prerogative. The government's position is that prerogative powers include the right to withhold information from Parliament on grounds of public interest. The client's company has recently been awarded a further government contract, which is unrelated to the committee's inquiry. The solicitor is aware that parliamentary proceedings are protected by parliamentary privilege. The solicitor must advise the client on the relationship between the royal prerogative and parliamentary privilege. A partner at the solicitor's firm has suggested that the prerogative overrides parliamentary privilege, but the solicitor is not sure this is correct. The client has asked the solicitor to confirm the position in writing.

Which of the following best describes the relationship between the royal prerogative and parliamentary privilege?

Question 3

Scenario

A solicitor is advising a government department that is considering whether to use prerogative power to impose sanctions on a foreign state. The department's legal adviser notes that Parliament has enacted the Sanctions and Anti-Money Laundering Act 2018 (SAMLA), which provides a statutory framework for imposing sanctions. The minister responsible for the department is reluctant to use the statutory framework because it requires parliamentary oversight and scrutiny. The minister asks whether the prerogative power to impose sanctions can be used instead. The legal adviser recalls the principle established in the De Keyser case regarding the relationship between prerogative and statute. The minister points out that the prerogative power to conduct foreign affairs is broader than the specific statutory provisions. The legal adviser also notes that SAMLA does not expressly abolish the prerogative power to impose sanctions. The minister's political adviser suggests that the prerogative could be used for types of sanctions not specifically covered by the Act. The legal adviser considers whether there is any scope for using prerogative power in this context. The department has recently received legal advice from the Attorney General's office on a related matter. The legal adviser recalls that the SAMLA framework was specifically designed to replace pre-existing EU sanctions mechanisms following Brexit. The minister asks for a definitive answer on the legal position.

Which of the following best describes the legal position regarding the use of prerogative power to impose sanctions?

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