Today is the third and final day of a legal challenge over the suspension of Parliament, taking place at the UK's highest court.
A panel of 11 Supreme Court judges will hear submissions on behalf of former Prime Minister Sir John Major, the Welsh and Scottish governments and Northern Irish victims' campaigner Raymond McCord, who are all against prorogation.
Boris Johnson insists the five-week suspension is to allow the government to set out a new legislative agenda in a Queen's Speech when MPs return to Parliament on October 14.
But those who brought the legal challenges argue the prorogation is designed to prevent Mr Johnson facing parliamentary scrutiny ahead of Brexit.
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15.20 - Ruling expected 'early next week'
The president of the Supreme Court, Lady Brenda Hale, said the court would rule on the proceedings "as soon as it humanly can".
It is expected a decision will be published early next week.
15.00 - Resume Parliament 'next week', says Lord Pannick
The judge representing campaigner Gina Miller has said he expects the Prime Minister to ensure Parliament resumes as early as next week, if the court asks him too.
Lord Pannick QC said: "The central issue is why was it appropriate to prorogue for five weeks, longer - as the court knows - than on any occasion in the past 40 years?".
It is Ms Miller's second Brexit-related legal battle.
The first was to get MPs to vote on whether the UK could start the process of leaving the EU; she argued the government could not invoke Article 50 without approval from Parliament.
14.00 - Parliament could remain suspended if PM loses
Parliament may remain suspended even if Boris Johnson loses at the Supreme Court.
Documents submitted to the court on his behalf today reveal three possible scenarios in the event the 11 justices conclude the Prime Minister's advice to the Queen to prorogue Parliament for five weeks was unlawful.
The first envisages a situation where the judges find it was unlawful, but their reasoning leaves open the possibility that Parliament could be prorogued for the same length of time in a lawful manner.
The document, submitted by Sir James Eadie QC and Advocate General for Scotland Lord Keen, states: "In that scenario, the court would and could not make any order purporting to require Parliament to be reconvened... Parliament would remain prorogued."
12.10 - Sir John Major: Johnson had 'ulterior motives'
Lord Garnier is representing the ex-Prime Minister
Lord Garnier, speaking on behalf of former Prime Minister Sir John Major, is currently arguing against the five-week prorogation.
He says the reasons put forward by Boris Johnson for the suspension "cannot be true", accusing him of having "ulterior motives".
Sir John is not in the courtroom.
11.40 - Welsh government's lawyer: Was proroguing in the public interest?
Mike Fordham is representing the Welsh government
Mike Fordham QC, representing the Welsh government, has asked whether the suspension of Parliament was in the public interest.
He argued that if that was not the case, then the court could intervene.
"Prerogative power has to be exercised in the public interest," he said.
11.00 - Court ruling would stop government 'trespassing on Parliament'
Speaking on behalf of Northern Irish victims' campaigner Raymond McCord, lawyer Ronan Lavery said if the court decided it could rule on this case, it would be preventing the government from "trespassing on Parliament".
"The court wouldn't be trespassing on Parliament, it would simply be preventing the government from trespassing on Parliament," he said.
Mr McCord, whose son was murdered by loyalist paramilitaries in 1997, brought separate legal proceedings in Belfast arguing that a no-deal Brexit would damage the Northern Ireland peace process.
10.30 - 'Parliamentary accountability' at stake
The lawyer representing the Scottish government has told the Supreme Court that proroguing had put "parliamentary accountability" at stake, and that the length of the suspension was not justified.
James Wolffe QC, said the prorogation was taking place at a "time-critical period", as any decision the government makes on Brexit will have "momentous consequences".
He has called for a "rigorous" review into Boris Johnson's actions.
09.30 - Ex-PM to slam prorogue decision
Ex-Prime Minister Sir John Major is set to accuse Boris Johnson of proroguing Parliament because of a "political interest" in closing it down ahead of Brexit.
He will not address the court himself, with his lawyer Lord Edward Garnier QC putting forward his argument.
It is unclear at this stage whether Sir John will appear in person at the court.