Scotland's highest court of appeal has ruled that the UK Prime Minister’s suspension of parliament is unlawful.
The UK Parliament prorogued in the early hours of Tuesday morning and is not due to return for five weeks.
That will leave just days before the crunch EU Summit at which Mr Johnson has claimed he aims to strike a new Brexit deal with Brussels.
This day last week, the Court of Session in Edinburgh found that the prorogation was lawful; however, that was immediately appealed.
In a unanimous decision this morning, the Inner House, which is the supreme civil court in Scotland, reversed last week's finding and found the prorogation unlawful.
However, the court made no order to reverse the suspension itself - with a full hearing to get underway at the Supreme Court in London next Tuesday.
The UK Government will use that hearing to appeal the ruling.
Nine judges will preside over the hearing which is expected to last three days.
The legal bid was launched by a group of 78 MPs, including SNP MP Joanna Cherry.
Following the ruling, she offered a "huge thanks to all our supporters & our fantastic legal team who have achieved the historic ruling."
— Joanna Cherry QC MP (@joannaccherry) September 11, 2019
A summary judgement handed today said the prorogation was "an egregious case of a clear failure to comply with generally accepted standards of behaviour of public authorities."
It suggested Mr Johnson has shut down Parliament for two reasons:
- To "prevent or impede parliament holding the executive to account and legislating with regard to Brexit"
- to "allow the executive to pursue a policy of a no-deal Brexit without further Parliamentary interference"
The Scottish case is one of three challenges to the Parliamentary suspension ,with other cases underway in London and Belfast.
The English challenge was launched by campaigner Gina Miller, with the former UK Prime Minister John Major and Labour deputy leader Tom Watson also involved.
This is great news, congratulations to you and all involved. This battle has further to run but my message to @BorisJohnson is you are playing fast and loose with the law. You have acted in an anti democratic manner and need to respond by recalling Parliament. https://t.co/EApHnB3fhQ
— Ian Blackford (@IanBlackfordMP) September 11, 2019
Mr Johnson insists the suspension is to allow for a new Parliamentary session and legislative agenda.
His opponents have said it an attempt to block debate on Brexit ahead of the October 31st deadline for the UKs departure from the EU.