The supreme court has ruled that Boris Johnson’s advice to the Queen that parliament should be prorogued for five weeks was unlawful.
Why did the Supreme Court case happen?
Two of the highest courts, one in England and one in Scotland, had previously considered the decision to suspend Parliament for five weeks (prorogation) - only to come to different conclusions.
The English case was brought by Gina Miller, the campaigner who previously forced the government to give MPs a vote on triggering the Brexit process. She was backed up by former prime minister Sir John Major.
A group of more than 70 Parliamentarians led by the SNP's Joanna Cherry QC brought the Scottish case.
Lawyers for the government were appealing against the decision in Scotland and defending the judgement in England.
The lawyers opposing the suspension sought to prove that Mr Johnson was trying to "silence Parliament" for five weeks - the longest period for 40 years - at a crucial political moment.
The Government said it had a right to create "a clear space when it is not subject to the daily grind" to prepare for a Queen's Speech - which would set out Mr Johnson's new government's plan for legislation - and to tackle Brexit issues.
In England's High Court, judges ruled that it was a political matter and not a decision for the courts. However, in Scotland, the Inner House of the Court of Session ruled the government acted unlawfully because it had the "improper purpose of stymieing Parliament" in the crucial period before the 31 October Brexit deadline.
This meant that the case was escalated to the Supreme Court, the final court of appeal in the UK for civil cases, and for criminal cases from England, Wales and Northern Ireland. It hears cases of the greatest public or constitutional importance affecting the whole population.
What happens now?
The Supreme Court was keen to emphasise that the case is not actually about Brexit. Lady Hale, president of the Supreme Court, said it is "solely concerned" with whether it was lawful for Boris Johnson to suspend Parliament through a process called prorogation.
The court's decision was unanimous, and the court deemed that it can rule on the prorogation of Parliament. It declared that the prorogation was null and void, therefore Parliament has not been suspended.
It is for Parliament to decide what to do next. Speaker John Bercow recalled Parliament, and MPs returned today, to hear from ministers and the Prime Minister.
A law designed to stop a no-deal Brexit on 31 October has been passed. If a deal is not agreed between the UK and EU by 19 October, and MPs don't vote in favour of leaving without a deal, then the prime minister will be legally obliged to ask the EU for a Brexit delay.
There are a number of scenarios that could now happen to read more about them click here.