The prime minister’s decision to suspend parliament until 14 October was unlawful, the Supreme Court has unanimously ruled.
Eleven justices were asked to determine the legality of Boris Johnson’s advice to the Queen to prorogue parliament, for what opponents described as an “exceptionally long” period.
The panel held unanimously that Mr Johnson’s advice was unlawful because it had the effect of frustrating parliament.
It also found the prorogation was “void and of no effect” – meaning parliament has not been suspended.
Lady Hale said: “The court is bound to conclude therefore that the decision to advise Her Majesty to prorogue was unlawful because it had the effect of frustrating or preventing the ability of parliament to carry out its constitutional functions.”
Labour leader Jeremy Corbyn told his party’s conference in Brighton: “It shows the prime minister has acted unlawfully in shutting down parliament.
“It demonstrates a contempt for democracy and an abuse of power by him.”
Following the decision Commons Speaker John Bercow said the House of Commons is preparing to resume tomorrow from 11.30am.
Mr Bercow said there would be no Prime Minister’s Questions but there would be scope for urgent questions, ministerial statements and emergency debate applications.
Mr Johnson had insisted the five-week suspension from 9 September was to allow the government to set out a new legislative agenda in a Queen’s Speech when MPs return to parliament.
But those who brought legal challenges accused the PM of an unlawful “abuse of power” and argued that the prorogation was designed to prevent parliamentary scrutiny of the UK’s impending exit from the EU on 31 October.
At the High Court in London, the Lord Chief Justice Lord Burnett and two other judges rejected a challenge against the prime minister’s prorogation (suspension) move by campaigner and businesswoman Gina Miller.
But in Scotland, a cross-party group of MPs and peers won a ruling from the Inner House of the Court of Session that Mr Johnson’s prorogation decision was unlawful because it was “motivated by the improper purpose of stymieing parliament”.
SNP MP Joanna Cherry, who led the case in the Scottish courts, said: “This is a huge victory for the rule of law and for democracy.
“As regards Mr Boris Johnson, the highest court in the United Kingdom has unanimously found that his advice given to Her Majesty the Queen was unlawful.
“His position is untenable and he should have the guts for once to do the decent thing and resign.”
:: Analysis by Sky News home editor Jason Farrell
We expected constitutional history leading to legal and political tremors – we got an earthquake. The government has lost on all levels.
The Supreme Court decided they do have a right to intervene, the prorogation was unlawful and this was not a parliamentary procedure, above legal oversight, this suspension was “imposed on parliament”.
It’s a devastating decision for Boris Johnson and hard to see a single positive other than perhaps that the court didn’t go into his motives.
They didn’t say he deliberately misled the Queen. But Lady Hale made clear that he had undermined the sovereignty of parliament, that the “effect was extreme” and it had been done “without reasonable justification”.
The truth is that government lawyers never even tried to justify the government’s position. They took the first line of defence by saying the courts had no right to interfere.
Once Lady Hale bust that door down – by quoting laws dating back to 1611 – then the government’s whole case collapsed.
This isn’t about how we leave the EU other than – as Lady Hale pointed out – the prime minster tried to remove five of the eight weeks of sitting time between recess and the Brexit date.
Crucial time for parliament to do its job. Well, now they will be back and scrutinising harder than ever – a wounded and humiliated prime minster.
The prime minister’s decision to suspend parliament until 14 October was unlawful, the Supreme Court has unanimously ruled. Eleven justices were asked to determine the legality of Boris Johnson’s advice to the Queen to prorogue parliament, for what opponents described as an “exceptionally long” period.