That brings our live coverage of the Supreme Court proceedings to an end for the day. The court will be back tomorrow to hear more from both camps.
Boris Johnson's suspension of Parliament in UK Supreme Court
By Eliza Mackintosh and Sheena McKenzie, CNN
We're closing our live coverage
Here's what observers made of the day's proceedings
British journalists have been digesting the first day of arguments at the Supreme Court. Here's what a few of them made of it all.
The BBC's Dominic Casciani noted that much of the debate was focused on whether the prorogation was a political matter, or one for the courts to weigh in on.
Carl Gardner, who served as a government lawyer for 12 years, suggested that Gina Miller and Joanna Cherry's teams will be happier than the government's at the end of day 1.
Legal expert Joshua Rozenberg picked up on a few queries the judges had for the government's lawyer, Lord Kerr, at the end of the day's proceedings.
But barrister Adam Wagner also felt the government could have ground to make up.
The court has adjourned for the day
That's it -- a lengthy first day at the Supreme Court is over.
It will return tomorrow, as both appeals continue to be heard by the 11 judges.
So how long *is* this prorogation?
Lord Keen has engaged in a back-and-forth with Lord Kerr, one of the judges, about the practical length of the prorogation.
The government's lawyer argued it is "perfectly clear" that the suspension is of a maximum of seven days, given that it came either side of an anticipated recess for conference season. He accused the Scottish courts of misinterpreting the suspension, by saying in their judgement that it would last five weeks.
Keen is almost certainly correct that Parliament would not have been sitting for conference season -- it never does.
But the government has still prorogued Parliament for five weeks, rather than waiting until the end of conference season and proroguing it for a week at that point.
That formed the basis of one of Kerr's questions on the matter, before Keen wrapped up his statement.
Is this a decision for the Supreme Court? The government's lawyer doesn't think so
From CNN's Luke Hanrahan inside London's Supreme Court
Lord Keen tells the judges it's not the Supreme Court's job to decide whether the Prime Minister's decision to prorogue Parliament for five weeks is legal or not.
"The court is not equipped to decide what is a legitimate political consideration and what is is an illegitimate consideration," says Keen, the lawyer representing the UK government.
Essentially, he's arguing that what Boris Johnson has done is political, and that it's not up to the courts to intervene.
Government lawyer won't comment on whether PM would prorogue Parliament again
From Arnaud Siad and Luke Hanrahan
Lord Keen is being asked what Prime Minister Boris Johnson will do if the Supreme Court upholds a ruling by Scotland's highest court of appeal that his decision to prorogue Parliament was unlawful.
Keen says: "The consequence could be that he goes to the Queen and seeks the recall of Parliament.”
The judges push Keen on this point, asking whether Johnson "would prorogue Parliament again?"
Keen replies: “I’m not in a position to comment on that proposition."
Millions tune into live stream of court hearing
The live stream of Tuesday's Supreme Court hearing has already been accessed 4.4 million times, the UK's PA news agency reports.
Usually the live streaming service is accessed just 20,000 times a month, according to PA.
Happening now: UK government's appeal against Scottish court ruling
Lord Keen, the lawyer representing the UK government's appeal against the ruling by the Scottish Court of Session last week, is now addressing the judges.
Quick re-cap: The case refers to a group of more than 70 lawmakers, led by Scottish National Party MP Joanna Cherry, who joined forces to sue the Prime Minister and prevent the suspension of Parliament.
On Wednesday their case was successful, with Scotland's highest court ruling that Johnson's decision to suspend Parliament was motivated by the "improper purpose of stymying Parliament."
Some key takeaways from British political journalists so far
A quick round up of musings from British political heavyweights. Looks like the big question of "justiciability" -- whether the court or Parliament has the right to make a decision on prorogation -- is the key point in the case from Lord Pannick (Gina Miller's lawyer).
ITV's Robert Peston says "judges will have to decide whether the five-week prorogation was disproportionately long."
The BBC's Dominic Casciani says Pannick "wants the courts to focus on PM's intention and its effect on Parliament's sovereignty."
Ian Dunt, the editor of Politics.co.uk, points out what many of us watching were perhaps thinking: that the real gems of information are often hidden among piles of administrative documents.