LS.06 — The Royal Prerogative

What it is

The prerogative is the residue of common-law powers and privileges held by the Crown (exercised by ministers in the monarch's name). It is common-law, not statutory — no Act creates it; courts recognise it. Dicey: "the residue of discretionary or arbitrary authority…legally left in the hands of the Crown."

Core rules / tests

• No new prerogatives. Courts will not recognise any new ones (BBC v Johns [1965]). The body of prerogative powers is fixed and can only shrink.
• Statute prevails. Where statute covers the same ground, the prerogative is held in abeyance (suspended) for as long as the statute is in force — Attorney-General v De Keyser's Royal Hotel [1920]. Ministers cannot use the prerogative to frustrate a statutory scheme (R v SS Home Dept, ex p Fire Brigades Union [1995]).
• Examples: foreign affairs/treaties, deployment of armed forces, granting honours, the prerogative of mercy, issuing/withdrawing passports, appointing ministers.

Justiciability and review

• GCHQ case (Council of Civil Service Unions v Minister for the Civil Service [1985]): the exercise of prerogative power is reviewable in principle — what matters is subject-matter, not source. But some areas remain non-justiciable (treaty-making, national defence, mercy, dissolution-type matters).
• Existence/extent of a prerogative is always for the courts to determine (Miller (No.1) / Miller (No.2)).

Leading modern cases

• Miller (No.1) [2017]: ministers could not use the prerogative to trigger Art 50 — doing so would remove statutory rights, so an Act was needed. Prerogative cannot override statute or change domestic law.
• Miller (No.2)/Cherry [2019]: prorogation advice unlawful where it frustrates Parliament's constitutional functions without reasonable justification; courts can review the limits of a prerogative.

Common traps / distinctions

• Don't confuse "monarch" with "ministers." Most prerogative power is exercised by ministers on the Crown's behalf, not personally by the King.
• Abeyance ≠ abolition. A statute that displaces a prerogative only suspends it; repeal could revive it.
• Source vs exercise: the source (prerogative vs statute) no longer determines reviewability — GCHQ turned that off; focus on justiciability of the subject matter.
• No new prerogatives — a tempting wrong answer is a minister "creating" a power.
• The Fixed-term Parliaments Act 2011 abolished the dissolution prerogative, but the Dissolution and Calling of Parliament Act 2022 repealed the FTPA and revived the prerogative power to dissolve (with an ouster clause purporting to exclude judicial review) — a clear statutory-to-prerogative shift to know.