British prime minister Boris Johnson suffered a fresh blow Wednesday when a Scottish court ruled that his controversial decision to suspend parliament in the run-up to Brexit was unlawful.
The government immediately appealed, with the case set to be heard in the Supreme Court next Tuesday, and parliament set to remain shut in the meantime.
Johnson says the decision to suspend -- or prorogue -- parliament until October 14 is a routine move allowing his government to launch a new legislative agenda.
But critics accuse him of trying to silence parliamentary opposition to his threat to leave the European Union on October 31 even if he has failed to agree divorce terms with Brussels.
If Johnson fails to secure a deal he insists the country will leave anyway, to the outrage of many MPs who believe a "no deal" exit would bring huge disruption.
After the legal ruling, the opposition Labour party demanded that Johnson urgently recall parliament, which was suspended for five weeks on Tuesday.
However, a government source told AFP that "nothing is changing" until the case was concluded.
The case, brought by 78 British lawmakers, was rejected by a Scottish lower court last week but was overturned Wednesday by the Inner House, Scotland's supreme civil court.
It found that Johnson's advice to Queen Elizabeth II to prorogue parliament "was unlawful because it had the purpose of stymying parliament", a summary judgement said.
A British 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."
He noted a separate legal challenge to prorogation brought at the High Court in London last week had failed.
Labour's Brexit spokesman Keir Starmer welcomed the ruling, saying: "No one in their right mind believed Boris Johnson's reason for shutting down parliament.
"I urge the prime minister to immediately recall parliament so we can debate this judgement and decide what happens next."
Scotland's first minister, Scottish National Party (SNP) leader Nicola Sturgeon, echoed his call.
"The immediate political implications are clear... parliament must be recalled immediately to allow the essential work of scrutiny to continue," she tweeted.
The summary judgement said the court would make an order declaring that Johnson's advice to the queen and the subsequent prorogation was "null and of no effect".
However, the government source said there would be no order issued ahead of next week's appeal.
Legal commentator David Allen Green suggested that the case was likely to fail when it reached the Supreme Court, pointing out that Scottish law was different from that of England and Wales.
"That is why I and others would have put the chances of the action succeeding in London as zero. And that is why cannily the action was launched in Scotland, where judges and the law would be far more receptive," he tweeted.
Johnson took office in July promising to deliver on the 2016 referendum vote for Brexit by taking Britain out of the European Union on schedule on October 31 whatever the circumstances.
He says he is working hard to agree new exit terms, after the deal negotiated by his predecessor Theresa May was rejected by MPs, despite EU leaders insisting the current terms are the best on offer.
Last week, between returning from their summer holidays and parliament's suspension, MPs passed a law to force Johnson to delay Brexit if he does not get a new deal by an EU summit on October 17-18.
Spanish Prime Minister Pedro Sanchez said Wednesday that the bloc should not make any further concessions to Britain.