Boris Johnson’s five-week suspension of parliament has been ruled unlawful by the highest appeal court in Scotland, with a panel of three senior judges concluding that the order to close the doors of Westminster to MPs was therefore "null and of no effect".
In a unanimous decision in Edinburgh’s Court of Session, the judges ruled that the prorogation was unconstitutional, as documents provided by the government itself had shown that its "true purpose" was to stifle parliamentary scrutiny.
In a written ruling, the judges stated that the prime minister's advice to the Queen to shut parliament down until 14 October "was motivated by the improper purpose of stymying parliament and that it, and what has followed from it, is unlawful."
They said that the prime minister's advice on the monarch's exercise of prerogative power would not normally be subject to judicial review, unless its purpose was "to stymie parliamentary scrutiny of the executive, which was a central pillar of the good governance principle enshrined in the constitution".
In a damning conclusion, which amounts to a rejection of Mr Johnson's claim that the prorogation was nothing to do with Brexit but purely in order to allow time to prepare for a Queen's Speech, the ruling stated: "The circumstances in which the advice was proffered and the content of the documents produced by the respondent demonstrate that this was the true reason for the prorogation."
It said: "The court will accordingly make an order declaring the prime minister's advice to HM the Queen and the prorogation which followed thereon was unlawful and is thus null and of no effect."
One of the 78 MPs who brought the case, the Scottish National Party’s Joanna Cherry, called for an immediate recall of parliament, which was dramatically shut down by the prime minister in the early hours of Tuesday.
And she was backed by Scottish first minister Nicola Sturgeon, who said: "Today’s Court of Session judgment is of huge constitutional significance - but the immediate political implications are clear. Court says prorogation was unlawful and null and void - so Parliament must be recalled immediately to allow the essential work of scrutiny to continue."
Anti-Brexit barrister Jolyon Maugham QC, who was a petitioner in the case, said he believed the effect of the decision was that "parliament is no longer prorogued".
Ms Cherry - also a QC - said: "We feel completely vindicated. I feel confident the Supreme Court will uphold this decision.
"This was a plot by Boris Johnson and Jacob Rees-Mogg and others to prevent us representing our constituents' views, prevent us scrutinising them as they take us through a back-door Brexit."
“Parliament should be immediately reconvened,” said SNP MP Tommy Sheppard. “The prime minister should come back to face the music.”
Shadow Brexit secretary Sir Keir Starmer was informed of the ruling after giving a speech to the TUC in Brighton and declared: "I'd better get back to London."
Sir Keir vowed to "get Boris Johnson back in parliament" to hold him to account over Brexit.
He told delegates: "It was obvious to everybody that not only was shutting down parliament at this crucial time obviously, the wrong thing to do, we should be sitting each and every day to resolve this crisis."
A UK government spokesman said: “We are disappointed by today’s decision, and will appeal to the UK Supreme Court. The UK government needs to bring forward a strong domestic legislative agenda. Proroguing parliament is the legal and necessary way of delivering this.”
The office of Commons Speaker John Bercow said that it would be for the government to recall parliament if that proved necessary during prorogation.
"Any decision to accelerate the meeting of parliament during prorogation is a matter for the government," said a spokeswoman.
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