LONDON: Britain's Supreme Court ruled on Tuesday (Sep 24) that a decision by Prime Minister Boris Johnson to suspend parliament in the run-up to Brexit was "unlawful", saying it was "void and of no effect".
The 11 judges of the country's highest court were unanimous in their verdict, which they said meant parliament could now immediately reconvene.
"The decision to advise her Majesty to prorogue parliament was unlawful because it had the effect of frustrating or preventing the ability of parliament to carry out its constitutional functions without reasonable justification," Supreme Court president Brenda Hale said.
"Parliament has not been prorogued. This is the unanimous judgment of all 11 justices," she added. "It is for parliament, and in particular the speaker and the lords speaker, to decide what to do next."
The decision was a stunning blow to Johnson that sparked immediate calls for him to resign.
Parliament was suspended, or prorogued, from Sep 10 to Oct 14. The prorogation was approved by Queen Elizabeth, Britain's politically neutral head of state, acting on the advice of the prime minister as she is required to do under the country's complex, uncodified constitution.
Johnson had argued that shutting down parliament until Oct 14 was a routine move to allow his new government to set out a new legislative programme.
But critics accused him of trying to silence MPs ahead of Britain's scheduled exit from the European Union on Oct 31 - the terms of which remain unclear.
House of Commons speaker John Bercow said after the ruling on Tuesday that parliament must "convene without delay".
The judges "have vindicated the right and duty of parliament to meet at this crucial time to scrutinise the executive and hold ministers to account", he added.
Bercow, who has been highly critical of Johnson's decision, said he would be consulting party leaders "as a matter of urgency".
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"JOHNSON MUST RESIGN"
Labour leader Jeremy Corbyn called on Johnson to consider his position and call a new election.
To huge cheers and chants of "Johnson out!" at the Labour Party's annual conference in Brighton, Corbyn said the British prime minister should become the shortest-ever serving leader and that Labour was ready to form a government.
"I invite Boris Johnson, in the historic words, to 'consider his position' and become the shortest serving prime minister there has ever been," Corbyn told delegates.
The Westminster leader of the Scottish National Party (SNP), Ian Blackford, said: "We must be back in parliament immediately.
"We want to get back to work. On the back of this, Boris Johnson must resign."
Most members of the House of Commons oppose Johnson's threat to leave the European Union next month - even if he has not agreed exit terms with Brussels.
In two separate cases, more than 75 lawmakers and a team backed by former Conservative premier John Major had challenged the prorogation as unlawful.
One had failed in the High Court in England, while another succeeded in Scotland's highest civil court - with the Supreme Court asked to make the final ruling.
Johnson on Tuesday responded by renewing his call for the rival Labour Party to back new elections.
"The obvious thing to do is call an election. Jeremy Corbyn is talking out the back of his neck," Johnson told reporters on a visit to New York.
"And he should have an election," Johnson said.
"NO TIME TO LOSE"
The court's decision is the most dramatic in the turbulent Brexit process, and comes at a crucial time.
Johnson has insisted Britain must leave the EU on Oct 31 no matter what, more than three years after the 2016 referendum vote for Brexit.
But the law passed by parliament earlier this month demands he ask EU leaders for a delay if he has not got a divorce deal by a Brussels summit on Oct 17.
He has expressed optimism that he can agree new terms by then, to replace the deal struck by his predecessor Theresa May, which was rejected by MPs.
But EU leaders are not as hopeful.
The bloc's chief negotiator, Michel Barnier, said Monday that London's current position did not offer any "basis to find an agreement" on leaving.
Johnson met EU Council President Donald Tusk in New York on Monday, after which the latter tweeted: "No breakthrough. No breakdown. No time to lose."
The British prime minister also held talks in New York with the French and German leaders, while further meetings with European colleagues are planned on Tuesday.
However, there is speculation he may now have to return to face a crisis at home.