Image source, UK Supreme Court

The UK's Supreme Court has ruled that Prime Minister Boris Johnson acted unlawfully when he advised the Queen to suspend Parliament.

To read the full text of the statement by Lady Hale, president of the court, click here.

Image source, PA

"None of us ever thought that the court would go so far as actually to quash the prorogation. Parliament has not been suspended, it has not even adjourned," says Anna Soubry MP, leader of the Independent Group for Change.

"Effectively, we are still sitting and the sooner we get back into that chamber the better."

She adds: "We are willing and ready to get into that chamber to hold this government to account and to ask the many questions that we need to ask of this prime minister."

Tory MP Tom Tugendhat has tweeted a picture of himself in the Commons to say he has already returned, will others follow?

Clive Coleman
BBC legal correspondent

I do not think any of us saw this being a unanimous ruling by all 11 justices.

This is the most muscular example of judicial review, able to stop the government in its tracks.

It is ground-breaking, it is extraordinary, the consequences politically, constitutionally, are seismic.

We should just take a step back and pause for a moment.

This is a ruling that says that a prime minister of the United Kingdom has unlawfully prorogued the sovereign body in our constitution – Parliament.

Nobody saw this coming.

Reality Check

Image source, Getty Images

BBC Reality Check has been looking at the role of the UK Supreme Court and why it had the final say in this case.

You can read the guide here.

Norman Smith
Assistant political editor

The chorus of voices calling for Boris Johnson to quit will now grow louder.

MPs can walk back into the chamber now if they want

The grit in all this is the government.

Downing Street say they are “processing” the judgement.

We have never been here before.

There are all sorts of ramifications for this government.

It is hard to estimate how much damage it does to Boris Johnson’s standing, his position, his authority.

We are in total uncharted territory.

Dominic Casciani
Home Affairs Correspondent

Justices Lady Hale and Lord Reed write in paragraph 61 of the judgement document: "It is impossible for us to conclude on the evidence... that there was any reason - let alone a good reason - to advise Her Majesty to prorogue Parliament for five weeks."

I'm still picking my jaw up off the floor.

Image source, Getty Images

London Mayor Sadiq Khan says Boris Johnson "misled the British public, Parliament, the Queen and the Courts" about the reason he prorogued Parliament.

"The truth is that the prime minister wanted to silence our MPs and prevent them from debating and scrutinising his catastrophic plans for a no-deal Brexit.

"Parliament must now be immediately recalled so that MPs can get on with their job of holding this undemocratic and dishonest government to account."

Image source, AFP

"I invite Boris Johnson, in the historic words, to consider his position and... become the shortest-serving prime minister there has ever been," says Labour leader Jeremy Corbyn.

"So, obey the law, take no-deal off the table and have an election to elect a government that respects democracy, that respects the rule of law and brings power back to the people, not usurp it in the way that Boris Johnson has done," he adds.

BBC assistant political editor Norman Smith says the Supreme Court ruling has left Boris Johnson's survival looking uncertain, and some MPs are already calling for his resignation:

The Brexit Party leader, Nigel Farage, describes the prime minister's decision to suspend Parliament as "the worst political decision ever" following the Supreme Court defeat.

He calls for his chief adviser, Dominic Cummings, to quit.

Image source, PA

"This is a huge victory for the rule of law and for democracy," says Joanna Cherry, SNP MP and leader of the group of politicians who brought the Scottish case.

"The courts have decided that it has long been the law in England and indeed in Scotland that the government is subjected to parliamentary scrutiny by members of parliament elected by the people," she adds.

"That is a decision in law, not a political decision... the Supreme Court [has] simply made it possible for us to get back in there and hold this government to [account]," she says, gesturing at Westminster.

She adds that Boris Johnson's "position is untenable".

"He should have the guts for once to do the decent thing and resign."