British High Court Rules Parliament Must Vote To Leave EU To Complete Brexit Process
Parliament must vote on whether the UK can start the process of leaving the EU, the High Court has ruled.
This means the government cannot trigger Article 50 of the Lisbon Treaty - beginning formal exit negotiations with the EU - on its own.
Theresa May says the referendum - and existing ministerial powers - mean MPs do not need to vote, but campaigners called this unconstitutional.
The government is appealing, with a further hearing expected next month.
The prime minister's spokeswoman said she would be calling President of the EU Commission Jean-Claude Juncker to say she intended to stick to her March 2017 deadline for triggering Article 50.
Amid suggestions that she might try to call an early general election, she added that Mrs May believed "there shouldn't be an election until 2020 and that remains her view".
A statement is to be made to MPs on Monday but the government says it has no intention of letting the judgement "derail Article 50 or the timetable we have set out".
Brexit Secretary David Davis said he presumed the court ruling meant an act of Parliament would be required to trigger Article 50 - so would be subject to approval by both MPs and peers.
But the government was going to contest that view in an appeal, and said the referendum was held only following "a six-to-one vote in the Commons to give the decision to the British people".
"The people are the ones Parliament represents - 17.4m of them, the biggest mandate in history, voted for us to leave the European Union. We are going to deliver on that mandate in the best way possible for the British national interest," he told the BBC.
Labour leader Jeremy Corbyn urged the government "to bring its negotiating terms to Parliament without delay", adding that "there must be transparency and accountability to Parliament on the terms of Brexit".
But UKIP leader Nigel Farage said he feared a "betrayal" of the 51.9% of voters who backed leaving the EU in June's referendum and voiced concern at the prospect of a "half Brexit".
BBC assistant political editor Norman Smith said the court ruling could mean potentially "months and months" of parliamentary hurdles but said a majority of MPs would be likely to vote for Article 50 - despite having backed the Remain campaign - as Brexit had been supported in the referendum.
