Held: giving a unanimous judgment, the Court concluded that the case was about the limits of the prerogative power to advise Her Majesty to prorogue Parliament. The power to prorogue is limited by the constitutional principles – of Parliamentary Sovereignty and Parliamentary accountability – with which it would otherwise conflict. As such the decision was justiciable.
The relevant limit on the power to prorogue is – it will be unlawful if it frustrates or prevents the ability of Parliament to carry out its constitutional functions without reasonable justification. This was not a normal prorogation in the run-up to a Queen’s Speech. It prevented Parliament from carrying out its constitutional role for five out of the possible eight weeks between the end of the summer recess and exit day on 31 October. Proroguing Parliament is quite different from Parliament going into recess. While Parliament is prorogued, neither House can meet, debate or pass legislation. No justification for taking action with such an extreme effect has been put before the court.
As such, the Court is bound to conclude, therefore, that the decision to advise Her Majesty to prorogue Parliament was unlawful because it had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions without reasonable justification. Prorogation is not a “proceeding in Parliament” and therefore not privileged under the Bill of Rights. The Order in Council is quashed and of no effect: Parliament has not been prorogued.
The Advocate General’s appeal in the case of Cherry is dismissed and Mrs Miller’s appeal is allowed.
Aidan O’Neill QC was involved in this case.