Shock Brexit court ruling - what does it mean for Boris Johnson?

SNP MP Joanna Cherry celebrates at the Court of Session

Judges have said that "the Court will accordingly make an Order declaring that 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."

And Jolyon Maugham QC, the head of the Good Law Project that brought the case on behalf of 78 parliamentarians, tweeted: “We believe that the effect of the decision is that Parliament is no longer prorogued.”

But there is no mechanism for MPs to be recalled between parliamentary sessions except at the request of the Prime Minister - and the government has said it will appeal the decision to the Supreme Court.

Boris Johnson's suspension of Parliament ruled as unlawful

However, it is a highly visible sign of the constitutional crisis that the UK has slid into, and the ruling also has the potential to be hugely politically damaging for Boris Johnson, a Prime Minister who has had his honesty and integrity questioned more than any other premier a few weeks into the job.

The language used by three judges, including the head of the Scottish judiciary Lord Carloway, is scathing: “This was an egregious case of a clear failure to comply with generally accepted standards of behaviour of public authorities”.

The ruling also goes beyond simply ruling that prorogation is unlawful, arguing that rather than suspending parliament to allow a new legislative programme through a Queen’s Speech, the government’s decision was made for the "improper purpose of stymying Parliament".

Johnson’s critics will leap on that to support their claim that Johnson misled parliament, the country - and potentially the Queen. Maugham told Sky News following the judgement that the sovereign would be “rather brassed off about the advice that was given to her by Jacob Rees-Mogg… it certainly has put her in a difficult situation”.

A defeat in court after six losses in the Commons before prorogation also gives the opposition a chance to frame Johnson as a serial loser who can’t win in or outside of parliament. And if the Supreme Court upholds the ruling, there is the embarrassing prospect of an order to ‘unsuspend’ parliament in the middle of the party conference season - although MPs would not have been sitting over that period in any case.

Already, Downing Street is seeking to hit back politically, with a source quoted as saying that “legal activists choose the Scottish courts for a reason". The SNP will leap on that reaction. The nationalist leader at Westminster, Ian Blackford, told the Scotsman shortly after the news broke: “Boris Johnson has got to see the error of his ways. He is not above the law.”

Finally, while there are dozens of MPs backing the case, one of them has had the greatest profile. This counts as a personal victory for Joanna Cherry, who just a few months ago was having her place in the SNP questioned as she came under fire from colleagues at Westminster. Today’s ruling confirms that she is one to watch.