LONDON — A Scottish court ruled Wednesday that Boris Johnson’s decision to suspend Parliament was illegal, escalating an already passionate debate over whether the British prime minister respected the rule of law and intended to adhere to it.
The ruling does not mean Parliament will immediately come back into session. But it does give the prime minister’s opponents hope ahead of an expected Supreme Court hearing next week. Some even raised the prospect that Johnson will have to resign if he loses that case.
A panel of three Scottish judges ruled that the government had been misleading — including, perhaps, to the queen — about its real reasons for the five-week suspension and that the move was “unlawful because it had the purpose of stymying Parliament” ahead of the scheduled deadline for Britain to leave the European Union.
The Supreme Court case will be heard on Tuesday after the prime minister’s office said it would appeal the Scottish ruling. “We are disappointed by today’s decision,” 10 Downing Street said. A government spokesperson later ruled out recalling Parliament at least until the Supreme Court has a chance to weigh in.
Wednesday’s ruling contradicts two other judgments. Courts in England and Wales had ruled that Johnson’s move was legal. Another Scottish judge, meanwhile, had decided that the courts did not have the authority to interfere in the suspension.
Scotland has a separate legal system from England and Wales; the Supreme Court, which is based in London, rules on matters relating to both jurisdictions.
Johnson’s critics celebrated Wednesday’s decision, saying they had been “vindicated.”
“You cannot break the law with impunity, Boris Johnson,” Joanna Cherry, one of more than 70 lawmakers who brought the case in Scotland, told reporters outside the court in Edinburgh. “The rule of law will be upheld by Scotland’s courts, and I hope also the Supreme Court of the United Kingdom.”
The leader of Cherry’s Scottish National Party, Nicola Sturgeon, called for Parliament to be “recalled immediately to allow the essential work of scrutiny to continue.”
The Labour Party joined that demand. “This ruling shows that, despite what Boris Johnson has spent his privileged life thinking, he is not above the law,” said Shami Chakrabarti, Labour’s point person on legal issues.
Meanwhile, Dominic Grieve, a former attorney general, said fellow Conservative Johnson should step down if it turns out he “had misled the queen about the reasons for suspending Parliament.”
“That would be a very serious matter indeed,” he told the BBC. “Indeed, in my view, it would then be the moment for Mr. Johnson to resign, and very swiftly.”
Queen Elizabeth II had agreed to prorogue — or suspend — Parliament, on the advice of the prime minister, as is customary.
The court battle over suspension could ultimately be a prelude to yet another legal battle that may arise from Brexit. Parliament last week passed a law requiring Johnson to seek an extension to the Oct. 31 deadline for Britain’s exit from the European Union if Johnson cannot strike a deal before then.
But the prime minister has repeatedly insisted he will not request the delay — he said last week he would “rather be dead in a ditch” — and unnamed advisers have told the British media Downing Street intends to “sabotage” the law.
Hard-line Brexit lawmakers have gone further, urging the prime minister to become “a martyr” to the cause and defy Parliament, even if it means being held in contempt of court and sent to jail.
A YouGov poll published this week found that 52 percent of Britons who backed “leave” in the Brexit referendum want Johnson to break the law if that is necessary to get Britain out of the E.U.
Cabinet ministers have played down the idea of the prime minister breaking the law, but have acknowledged that the government intends to “challenge the law to its limit.”
To some, the brewing standoff — when coupled with the court challenge over suspension — reflects an executive that lacks the respect for laws and conventions that had been a given in previous governments.
“You have a world of the rule of law, and you have a world of Dominic Cummings,” said Iain McLean, a politics professor at the University of Oxford, referring to Johnson’s chief strategist.
Cummings was the mastermind behind the pro-Brexit campaign group Vote Leave, which was fined for breaking legal spending limits during the 2016 referendum. Cummings was also found in contempt of Parliament after he refused to appear before a parliamentary group investigating fake news.
Christopher Carman, a politics professor at the University of Glasgow, said he did not expect Johnson to go to jail. But he said Johnson’s team would be “huddled in No. 10, trying to figure out how they can strictly comply with the law but perhaps not the spirit of the law.”
He noted that one idea recently discussed was Johnson sending the E.U. a request asking for a delay, along with a second letter saying he did not intend to use the delay.
Such a move probably would spawn a revolt in Parliament, where a majority of lawmakers, including renegade Conservatives, made clear last week they do not want a no-deal exit.
Parliament is not due to come back into session until mid-October under a plan that Johnson’s critics have charged was aimed at leading Britain over the cliff-edge of no-deal before lawmakers had time to block it.
A number of opposition politicians returned to Parliament on Wednesday anyway, as a way to protest the shuttering of the legislature. Some lawmakers tweeted pictures of themselves sitting on empty green benches in the House of Commons.
Suspending Parliament is not unusual. It often happens once a year, usually around May, before the government lays out its legislative agenda. But the length of the break and the timing prompted outrage — as well as the legal challenges.
At five weeks, the suspension is the longest since 1945, and it comes during what many observers believe to be Britain’s greatest peacetime crisis since the end of World War II.
Thousands of protesters have taken to the streets to demonstrate against what they called a “coup.” An activist group projected an image depicting Johnson as a criminal onto the side of the Houses of Parliament.
Jonathan Sumption, a former Supreme Court judge, told BBC Radio 4 that he thought the suspension was “politically outrageous” but that it didn’t seem to cross a legal line.
In the early hours of Tuesday, opposition lawmakers attempted to halt the suspension by physically preventing Speaker John Bercow from leaving his chair. They held aloft signs reading “Silenced” and chanted “Shame! Shame!” at their Conservative colleagues in one of the rowdiest sessions many longtime parliamentary observers could remember.
The prime minister’s office said suspending Parliament was “the legal and necessary way” for the government to “bring forward a strong domestic legislative agenda.”
But the judges found that that explanation was misleading, calling the government’s behavior “an egregious case of a clear failure to comply with generally accepted standards of behavior of public authorities.”
Cherry said the suspension was intended to “prevent us representing our constituents’ views and to prevent us scrutinizing them as they try to take us through a back door toward a no-deal Brexit.”
With Brexit in the balance, the outcome of the case next week could have high stakes. A return of Parliament would add even more unpredictability to an already confused environment and give lawmakers a greater chance to have their say as Johnson attempts to strike a deal with the E.U.
Wednesday’s decision is “incredibly bold,” McLean said. “Boris lied to the queen, is what it comes down to.”
He said he still thought the Supreme Court would rule the other way, “and so it could be a weak victory for the anti-Brexiteers. But who knows?”