R (Miller) v Prime Minister [2019] UKSC 41

Facts

• The Prime Minister advised the Queen to prorogue (end) the parliamentary session for five weeks.
• Historically, the power to prorogue Parliament derives from the Royal Prerogative, exercised by the government on behalf of the Crown.
• The prorogation occurred during a period of significant political importance prior to the Brexit deadline.
• The closure’s duration and timing attracted scrutiny over its effect on Parliament’s ability to pass legislation, scrutinize government actions, and ensure executive accountability.
• Legal challenges were brought to test whether the Prime Minister’s advice and the resulting prorogation could be reviewed by the courts and whether it was lawful.

Issues

1. Whether the Prime Minister’s advice to the Queen to prorogue Parliament was subject to judicial review.
2. Whether the use of the prerogative power to prorogue Parliament unlawfully frustrated or prevented Parliament from carrying out its constitutional functions.
3. Whether there was adequate justification for the length and timing of the prorogation.

Decision

• The Supreme Court held that the advice to prorogue Parliament was justiciable and not immune from judicial review.
• The Court determined that the prorogation prevented Parliament from carrying out its constitutional functions as lawmaker and overseer of the executive.
• It found no adequate justification for the length or timing of the closure, particularly given the political urgency.
• The Court ruled that the prorogation was unlawful and of no legal effect.

Legal Principles

• The Royal Prerogative must be exercised within limits set by constitutional and legal principles, especially where its use impacts Parliament’s ability to fulfill its constitutional functions.
• Government actions must not undermine fundamental constitutional principles or rights without express parliamentary authorisation.
• Even long-established prerogative powers can be subject to judicial review if their exercise threatens the constitutional balance.
• The judgment referenced Case of Proclamations (1611) 12 Co Rep 74 on limitations of prerogative authority and Attorney-General v De Keyser’s Royal Hotel Ltd [1920] AC 508 concerning the relationship between statute and prerogative.

Conclusion

The Supreme Court confirmed that the Prime Minister’s advice and the subsequent prorogation of Parliament were both justiciable and unlawful, reaffirming the limits on prerogative powers and the central role of Parliament in the UK’s constitutional structure.