The Government has lost its historic battle in the Supreme Court over Brexit.
The highest court in the land rejected an appeal by ministers against a High Court judgment blocking their decision to begin Britain's exit from the European Union without Parliament having a say.
Supreme Court justices ruled, by a majority of eight to three, that Prime Minister Theresa May cannot lawfully bypass MPs and peers by using the royal prerogative to trigger Article 50 of the Lisbon Treaty and start the two-year process of negotiating the UK's divorce from its EU partners.
The ruling is a blow to Mrs May, who has repeatedly said she intends to trigger Article 50 by the end of March following the clear majority in favour of Brexit in the June 2016 referendum.
It was won by a wide-ranging group of anti-Article 50 campaigners led by investment manager Gina Miller, 51, and hairdresser Deir Dos Santos.
However Britain still intends to start talks on leaving the European Union by the end of March, Downing Street said Tuesday.
"The British people voted to leave the EU, and the government will deliver on their verdict –- triggering Article 50, as planned, by the end of March," a spokesman for Prime Minister Theresa May's office said.
"Today's ruling does nothing to change that.
"We respect the Supreme Court's decision, and will set out our next steps to parliament shortly," the spokesman said.
"It's important to remember that parliament backed the referendum by a margin of six to one and has already indicated its support for getting on with the process of exit to the timetable we have set out," the spokesman said.