London - The ruling by the UK Supreme Court, which has found Boris Johnson's decision to suspend parliament unlawful, is a humiliating blow for the prime minister and has momentous implications for Britain's constitutional order.
Johnson announced the behind-closed-doors suspension decision -- known as a prorogation -- on August 28 while most MPs were still away on their summer holidays.
It caused widespread outrage as it was widely interpreted as a bid to limit the scope for MPs to have a say on Johnson's hardline Brexit strategy.
Multiple legal challenges were announced almost immediately, culminating in Tuesday's ruling by the highest court in the country.
Here is a rundown of the main questions it raises:
- What did the court decide?
The court's 11 judges decided first of all that they had the power to issue a ruling since "the courts have exercised a supervisory jurisdiction over the lawfulness of acts of the government for centuries".
It then ruled that Johnson's decision was "unlawful because it had the effect of frustrating or preventing the ability of parliament to carry out its constitutional functions without reasonable justification".
It said the advice that Johnson had given to Queen Elizabeth II, who as head of state formally issued the prorogation order, was "unlawful, void and of no effect".
UK Supreme Court strikes down parliament suspension
- Why is this significant?
Suspending parliament was a key part of Johnson's plan to deliver Brexit by October 31, even though MPs managed -- in the short time they were able to meet after their summer break -- to pass a law that could undermine this.
The decision also sets precedent, meaning that Johnson will face legal difficulties in trying to suspend parliament again. In constitutional terms, it means that the court's powers to allow parliament to have its say are stronger than an order issued by Queen Elizabeth II.
The court said that the circumstances were "exceptional" because of the looming prospect of Brexit, calling it a "fundamental change" for the country.
Parliament "has a right to have a voice in how that change comes about".
Graphic showing key events in the Brexit process in 2019
- When will parliament convene?
The ruling said the prorogation order was "void and of no effect" and that it was up to House of Commons speaker John Bercow and House of Lords speaker Norman Fowler to decide when to meet "as soon as possible".
Bercow has asked parliamentary authorities to make preparations for MPs to resume their proceedings from 1030 GMT on Wednesday.
He said the judges had "vindicated the right and duty of parliament to meet at this crucial time to scrutinise the executive and hold ministers to account".
The court said it was "not clear" whether any steps would be required from Johnson but if they were, "the court is pleased that his counsel have told the court that he will take all necessary steps to comply with the terms of any declaration made by this court".
- Will Boris Johnson resign?
The ruling is a huge embarrassment for Johnson, who has insisted his suspension of parliament was entirely legal because it was time for a new session to deal with his ambitious domestic agenda.
But it is unlikely the prime minister, who has only been in power since July, will step down.
Although his position in parliament is weak, opinion polls suggest his battles with MPs and judges over Brexit may actually be making him more popular with voters.
UK PM says disagrees but will respect Supreme Court ruling
By Dario Thuburn