A law analyst has said Britain's Supreme Court could request a Brexit extension on behalf of the government, if Prime Minister Boris Johnson doesn't abide by a law to seek a three-month delay.

Last week, members of parliament voted in favour of the government asking the European Union for the delay if no agreement is reached before October 31.

The law was rushed through Parliament before its suspension for five weeks.

The country's Supreme Court is set to decide on Tuesday whether the suspension, which was ordered by Johnson, is legal, after Scotland's highest civil court ruled the prorogation unlawful.

Steven Peers, professor of law at Essex University told the Associated Press that the Court is likely to support the government's Brexit plans "with some limits."

On Monday, Johnson will meet European Commission President Jean-Claude Juncker for the first time in an attempt to renegotiate a Brexit deal.

London - 16 September 2019

1. Various exteriors of British Parliament

2. Setup of Steven Peers, professor of law at Essex University:

3. SOUNDBITE (English) Steven Peers, professor of law at Essex University:

"Well what we've seen for the last six weeks or so is that the government, so Mr (British Prime Minister, Boris) Johnson, keeps saying that he thinks he's likely to get a deal and that they're moving towards a deal. But the signs from the EU, more or less seems, most of them to say that we're not moving much towards a deal. So, unless that somehow radically changes that's what I'd expect to sort of come out from today. Although everyone sort of jumps on what other people says and will take one word or one sentence out of what Mr (European Commission President, Jean-Claude) Juncker says and maybe the next five sentences, in order to say that he thinks we're about to do a deal. But you never know it's always possible that there's been work behind the scenes that we don't all know about that is moving us towards a deal. I wouldn't absolutely rule it out."

4. Cutaway of Peers' hands

5. SOUNDBITE (English) Steven Peers, professor of law at Essex University:

"Well I think lawyers tend to be conservative and the conservative approach, with a "small c," would be to say well let's not upset the traditional rule that governments can choose to suspend Parliament when they like. But then, the counter argument is that the government's doing more than usually suspending Parliament for just a few days here or there, it's doing it at a crucial period to stop Parliament challenging it over Brexit. The reasons it's given don't really hold up to close scrutiny. According to many people who adhere to the press it might just prorogue (suspend) Parliament again if it can. So, those are the concerns that the counter arguments have and maybe the judges will take them into account."

6. Cutaway of Peers

7. SOUNDBITE (English) Steven Peers, professor of law at Essex University:

"Well no one can predict anything. I mean the Supreme Court may or may not rule against the government. Labour MPs (Members of Parliament), may or may not. The DUP (Democratic Unionist Party) may or may not switch in sufficient numbers to pass a deal, they may or may not be successful in a deal. I mean, I think the more likely scenario is the Supreme Court supports the government with some limits, on maybe what it can do in the future and the government doesn't get a deal or doesn't get it passed. So we move into a scenario, of whether it's really going to ask for an extension as the law requires it to do, to ask for an extension of EU membership. I mean, I don't think anyone should be certain about their predictions."

8. Various exteriors of Parliament

9. SOUNDBITE (English) Steven Peers, professor of law at Essex University:

"Well, there are people who've already gone to court to try and get the law enforced, which perhaps might mean the court itself delivering a notice to the EU on behalf of the government that is requesting an extension. It might mean civil servants are ordered to act on behalf of the government, in order to request an extension or you could try and enforce the law directly against Boris Johnson – if he refuses that's contempt of court, which could mean jail time. But I think that's kind of drastic, the courts are more likely to try and find a way to do it without locking anyone up."

10. Various exteriors of Parliament

11. Pan-left from London Bridge to Parliament

British Prime Minister Boris Johnson did not advise the Queen to suspend Parliament for five weeks for any "improper purpose", Supreme Court justices have heard.

Barrister James Eadie, representing the Prime Minister, told the 11-strong panel that the suggestion the prorogation was intended to "stymie" Parliament ahead of Brexit was "untenable".

At the end of the second day of the hearing, there were jeers from pro-Brexit campaigners as transparency activist Gina Miller, who helped to bring the action, left the court building.

Legal expert Stefan Theil said it had been a good day for the government in court, but it was unclear which way the judges would lean when they make their ruling.

The court is hearing appeals on two separate challenges in the English and Scottish courts over the prorogation of Parliament.

The justices will continue to hear submissions on Thursday, the third and final day of the hearing, but it is not yet known when they will give a decision.

London - 18 September 2019

1. Gina Miller, transparency activist who is appealing against the High Court's decision that suspending parliament was not illegal, leaving court

2. Exterior of Supreme Court

3. Pro-Brexiteers shouting at Miller outside court

4. Various of pro-Brexiteers and supporters of Boris Johnson, UK Prime Minister, holding banners, British flags

5. Various of anti-Brexit protestors who are against the suspension of parliament, holding placards, banners

6. Zoom in of Joanna Cherry, Scottish National Party lawmaker

7. Police standing outside the Supreme Court

8. SOUNDBITE (English) Joanna Cherry, Scottish National Party lawmaker:

"And what's clearly coming to light, what's really clearly been emphasised today is the lack of candour on the part of the British Government about the reasons for the prorogation. Earlier today QC James Eadie, their lawyer, was asked if he could clarify what the reasons for the prorogation were and he wasn't prepared to do that other than by referring to the documents that have been lodged in court. But, it's been repeatedly emphasised today that there's no witness statements from the government accompanying those documents."

9. Stefan Theil, legal expert at Oxford University, talking outside the Supreme Court

10. SOUNDBITE (English) Stefan Theil, Oxford University:

"So the main points for the government were obviously that this is not judiciable, that was the one that was really quite leant on heavily. Justiciability means 'is this a thing that a court should look in to?', in other words can and should the court deal with this case and look in to the lawfulness of the prorogation? For the applicants respectively, the main issue was well, this was unlawful, the Prime Minister misled the Queen when advising her to prorogue Parliament and is doing it for an improper purpose."

11. Exterior of Supreme Court

12. Stefan Theil, Oxford University:

"It is really hard to say. Whenever you feel like you get a sense of what the judges are thinking, they immediately ask a question that sort of turns that on its head. So it's really hard to say. They're keeping their cards really closely to their chest. It's difficult to say. I think the government had a pretty good day today, I would say that. But again, it's about the law, it's less about the symbolism and the theatrics, so we'll have to wait and see."

13. Lawyers coming out of court

14. People waving Union Jack flags, cameras set up outside the Supreme Court

The Supreme Court in London on Wednesday began hearing its second day of legal debate over whether prime minister Boris Johnson acted lawfully by suspending - or proroguing - parliament.

Judges must determine if Johnson overstepped his authority by suspending Parliament for a five-week period during the run-up to the 31 October deadline for Britain to leave the European Union.

The government's opponents argued that Johnson illegally shut down Parliament just weeks before the country was due to leave the 28-nation bloc for the "improper purpose" of dodging lawmakers' legitimate scrutiny of his Brexit plans.

They also accused Johnson of misleading Queen Elizabeth II, whose formal approval was needed to suspend the legislature.

The government claims the suspension was routine, not related to Brexit, and was a matter for politicians rather than the court.

The judges will rule on two appeals - one by transparency campaigner Gina Miller' and one by the government challenging a Scottish court ruling against prorogation, or suspension.

The case is expected to conclude Thursday.

London - 18 September 2019

1. Various of exteriors of the Supreme Court

2. Police standing outside the Supreme Court

3. Transparency activist Gina Miller

4. Exteriors of the Supreme Court

5. Barrister and legal commentator, Jeremy Brier, using his mobile phone

6. The Supreme Court sign

7. SOUNDBITE (English) Jeremy Brier, barrister and legal commentator:

"So today the Supreme Court is hearing two appeals. It's hearing an appeal from the English High Court where they said prorogation and the question of suspension of parliament is not a justiciable matter, it's not for us, they're hearing an appeal from that. They're also hearing an appeal from the Scottish inner house which actually said the opposite - it said it is a matter for us and it was unlawful. So two different results that the Supreme Court has to consider on appeal and try and bring those cases together in one unified verdict."

8. Close of Jeremy Brier's hands

9. SOUNDBITE (English) Jeremy Brier, barrister and legal commentator:

"Today's a hugely significant day in this day two of the Supreme Court hearing.  We heard yesterday from Gina Miller's barrister Lord Pannick saying why prorogation, the suspension of parliament, was unlawful, that it thwarted parliamentary sovereignty. Today we hear from the government's QC Sir James Eadie. He's going to really be saying, this is not a question that the courts should be involved in, it's a non-justiciable matter. It's a matter of politics and there isn't a threshold, a measuring stick by which a court can sensibly get involved and work out what's legal and what's lawful."

10. Exteriors of the Supreme Court

11. Media standing outside the Supreme Court