CNN  — 

In a landmark decision that will have far-reaching implications, the UK Supreme Court has unanimously ruled that Boris Johnson’s decision to suspend Parliament for five weeks was unlawful.

What just happened?

In an extraordinary judgment, UK Supreme Court President Lady Hale said the Prime Minister’s advice to Queen Elizabeth II when he asked her to suspend, or “prorogue,” Parliament was “unlawful, void and of no effect.”

As a result, the court found: “Parliament has not been prorogued.”

All 11 judges agreed that Johnson acted illegally, suppressing parliamentary scrutiny of his Brexit strategy.

Lady Hale said Johnson’s advice to the Queen “had the effect of frustrating or preventing the ability of Parliament to carry out its constitutional functions without reasonable justification.”

Johnson’s decision to suspend Parliament until mid-October was hugely contentious. Opposition lawmakers accused the Prime Minister of trying to shut down efforts to stop a no-deal Brexit on October 31.

The government had insisted the prorogation was normal parliamentary procedure.

How unusual is this ruling?

It is unprecedented.

The decision is a huge defeat for Johnson, and will likely set off a bitter argument over whether the justices have strayed too far into the UK’s political arena.

Under the country’s unwritten constitution, Parliament, the government and the courts have defined roles in balancing out the others’ decisions.

The Supreme Court ruled that it had the right to pass judgment on Johnson’s decision to suspend Parliament, and, ultimately, that the five-week prorogation was unconstitutional.

Will Parliament reconvene?

Speaker of the House of Commons John Bercow speaks to the media outside the Houses of Parliament.

Yes.

The Supreme Court said it was up to Parliament “and in particular the Speaker and the Lord Speaker to decide what to do next.”

Shortly after the ruling, John Bercow, the Speaker of the House of Commons, told reporters the House of Commons would reconvene on Wednesday at 11:30 a.m. local time (6:30 a.m. ET).

Given that Johnson is currently in New York for the annual United Nations General Assembly, Bercow said it would not be possible to hold Prime Minister’s Questions, which usually occurs on Wednesdays.

But he said there would be “full scope” for urgent questions and ministerial statements.

The House of Lords, the UK Parliament’s upper chamber, will meet on Wednesday afternoon, and again on Thursday.

Announcing the news on Twitter, the Lord Speaker, Norman Fowler said: “The House of Lords performs a vital constitutional function. It holds the Government of the day to account and will continue to do just that.”

Will Boris Johnson resign?

There have been calls for Boris Johnson to resign.

This was the worst possible outcome for Johnson – a Prime Minister who has lost every vote he has faced in Parliament and seen his majority vanish.

But Johnson has not apologized for his decision to suspend Parliament. Indeed, a defiant Johnson said he “strongly disagrees” with the ruling.

“I have the utmost respect for our judiciary, I don’t think this was the right decision,” Johnson told reporters in New York Tuesday morning.

The main opposition parties have called for Johnson’s resignation or, in the case of the Liberal Democrats, said he is “not fit to be Prime Minister.”

Labour’s Jeremy Corbyn said Johnson should “consider his position,” which would make him “the shortest serving prime minster there has ever been.”

The Scottish National Party’s Joanna Cherry – who led the Scottish court action against Johnson – said the PM should resign: “His position is untenable and he should have the guts, for once, to do the decent thing and resign.”

Labour MP Job Trickett told the UK’s PA Media news agency that the party would likely demand that Johnson appear before lawmakers on Wednesday to explain himself.

“I suspect we will be summoning the Prime Minister to Parliament to make a statement,” Trickett said. “We want to hear what legal advice he was acting on, why he ended up in court and being ruled in this quite extraordinary way.”

Did Johnson lie to the Queen?

The Supreme Court did not say Johnson lied to the Queen about the reasons for his prorogation of Parliament.

Importantly, the judges ruled on the effect of the prorogation rather than attempting to define the motive, which allowed it to deliver a historic judgment without explicitly accusing Johnson of lying to the monarch.

Because the effect of the suspension was unlawful, the judges did not need to consider Johnson’s motive.

The key part of the ruling said: “It is impossible for us to conclude, on the evidence which has been put before us, that there was any reason – let alone a good reason – to advise Her Majesty to prorogue Parliament for five weeks, from 9th or 12th September until 14th October.

“We cannot speculate, in the absence of further evidence, upon what such reasons might have been. It follows that the decision was unlawful.”

The court did, however, uphold the decision taken by Scotland’s highest civil court, which went further in its ruling by saying that Johnson did mislead the Queen.

Is a no-deal Brexit still on the table?

There could be another political crisis on the horizon.

The October 31 deadline for the UK’s departure from the European Union is looming large.

Johnson insists that Brexit will go ahead on that date, even if he has not negotiated a deal by then.

“As the law currently stands, the UK leaves the EU on October 31 come what may,” Johnson said after the Supreme Court ruling.

Members of Parliament have already passed a law requiring Johnson to ask for another extension if he cannot secure a deal, so will he dare to defy Parliament?

Another possible twist is that the EU may not even agree to another extension.

The future is uncertain and a no-deal Brexit is still on the cards – as is a general election.