The Supreme Court has handed down its judgment in the challenge by Gina Miller to the Prime Minister’s advice to the Queen to prorogue Parliament. The Court sat as a panel of 11, only the second time in its history that it has done so. The Divisional Court of the High Court (the Lord Chief Justice, the Master of the Rolls and the President of the Queen’s Bench Division) had previously dismissed the claim, but granted a “leapfrog” certificate under s.12(3A)(c) of the Administration of Justice Act 1969 permitting an application for permission to appeal to be made directly to the Supreme Court. In a unanimous judgment, the Supreme Court allowed the appeal by Ms Miller. It held that the Prime Minister’s advice to the Queen to prorogue Parliament was justiciable. The relevant limit on the power to prorogue was that “a decision to prorogue Parliament (or to advise the monarch to prorogue Parliament) will be unlawful if the prorogation has the effect of frustrating or preventing, without reasonable justification, the ability of Parliament to carry out its constitutional functions as a legislature and as the body responsible for the supervision of the executive. In such a situation, the court will intervene if the effect is sufficiently serious to justify such an exceptional course”: . The Court held that the effect of the advice was to frustrate or prevent the constitutional role of Parliament in holding the Government to account: . The Court could not conclude, on the evidence before it, that any good reason had been provided for the prorogation of Parliament for five weeks and the decision was, accordingly, unlawful: . As regards remedy, the advice was unlawful, and the Order in Council to which it led was also unlawful, as was the actual prorogation. All three stages were described as “unlawful, null and of no effect”: . It followed that Parliament had not been prorogued: . The claim was heard alongside an appeal in similar proceedings involving Joanna Cherry MP and others from the Scottish Inner House of the Court of Session. The Inner House allowed that claim and declared the advice to be unlawful. The Supreme Court dismissed the Advocate General for Scotland’s appeal from that decision in the same judgment. There are also similar proceedings in Northern Ireland. David Blundell appeared on behalf of the Prime Minister in Miller, led by First Treasury Counsel, Sir James Eadie QC. The Supreme Court judgment can be found here. Press coverage is available here and here.