British Prime Minister Boris Johnson's decision to suspend parliament was unlawful, the Supreme Court ruled on Tuesday.
"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.
The ruling by the court's 11 presiding judges follows an emergency three-day hearing last week.
"Parliament has not been prorogued," Hale said. "It is for parliament, and in particular the speaker and the lords speaker, to decide what to do next."
Downing Street said it was "currently processing the verdict".
US House rejects war powers resolution, backs Trump on Iran war
GCC and EU ministers urge immediate halt to Iranian attacks
Trump wants say on Iran's next leader
British PM Starmer to send four Typhoon jets to Qatar
Bombing of Tehran intensifies as war enters day six
Azerbaijan vows to respond after four injured by Iranian drones
72 killed in Israeli attacks on Lebanon as it warns residents to leave south
Nepal goes to the polls; voters seek change after youth-led protests
