BBC News Channel

Former Conservative minister Crispin Blunt described the High Court judgement as "constitutional nonsense".

He says he fears the "unelected" House of Lords will stop the will of the people and the will of the House of Commons.

He hopes the Supreme Court will "rescue us from a constitutional crisis", he tells the BBC.

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Labour former minister David Lammy, who voted for the UK to remain in the EU, said he would be voting against the triggering of Article 50.

He described the High Court verdict as "a very, very important moment for our constitutional history".

"In the end this decision is about our parliamentary democracy," he said.

"It's not about Leave or Remain - it's about whether you believe in a sovereign parliament."

He added: "We can't have Theresa May playing the ultimate monarch."

House of Commons
Parliament

During the weekly statement outlining future business in the Commons, the Leader of the House David Lidington makes reference to the High Court's "lengthy and complex judgement", which he says is being studied by the Attorney General. 

He again confirms that the government intends to appeal to the Supreme Court.

He also announces that the government intends for there to be a statement to the Commons on the Article 50 judgement on Monday, so that MPs can quiz ministers.

Eleanor Garnier
Political Correspondent

It is one of the most important constitutional court cases in generations.  And the result creates a nightmare scenario for the government. 

Theresa May had argued she wanted to start Brexit talks before the end of March next year but today's ruling has thrown the Prime Minister's timetable up in the air. 

Campaigners who brought the case insist it was about "process not politics" but behind the doors of No 10 there will now be serious head scratching about what exactly the government's next steps should be.

This decision has huge implications not just on the timing of Brexit but on the terms of Brexit. That's because it has given the initiative to those on the Remain side in the House of Commons who, it is now likely, will argue Article 50 can only be triggered when Parliament is ready and that could mean when they are happy with the terms of any future deal.

Of course it will be immensely difficult to satisfy and get agreement from all those MPs who voted to Remain. Could an early General Election be on the cards after all?

House of Lords
Parliament

Lord Speaker Lord Fowler opens proceedings with a statement on the "sub judice" rules and the government's forthcoming appeal against today's Brexit court ruling.

He confirms that "noble Lords may make reference" to the case.

Peers laugh, and then cheer as Labour peer Lord Soley asks his question on the future UK relationship with the EU.

He says today's court judgement shows how fast-moving the situation is.

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Tahmid Chowdhury - one of six claimaints who crowdfunded their case calling for a vote on Brexit conceded that 17 million people voted to leave the EU, "but they didn't vote for any kind of Brexit".

Mr Chowdhury, from People's Challenge, said he wanted to see a bill on Brexit, followed by an Act of Parliament before the UK can leave the EU.

UKIP interim leader Nigel Farage has warned that Britain is heading to a “half Brexit” – and said that he would return to British politics in 2019 if Brexit hasn’t happened by then.

In an interview with BBC 5 Live's Emma Barnett, he said:

Mr Farage insisted he is "not going to disappear".

"If come spring of 2019 we haven't left the EU, then I would have to take up full-time campaigning again." 

Mr Farage also predicted that Theresa May would lose a vote in Parliament, if Thursday's decision ended up with a vote among MPs. 

Labour leader Jeremy Corbyn said the High Court ruling "underlines the need for the government to bring its negotiating terms to Parliament without delay".

Neil Wilson, a markets analyst at ETX Capital, says: “The High Court ruling on Article 50 is a body blow for Theresa May and the Brexit-leaning ministers at the heart of government. It’s made triggering Brexit a lot trickier and has given sterling a massive shot in the arm.

"The stage is now set for a fresh battle over Brexit and there is the prospect that parliament will block Britain’s withdrawal from the EU, albeit a dim and distant one for now. We need to get more clarity on what MPs think and intend to do about this now they have a say.

"In a year of political surprises, who would bet against another one? A massive grass-roots remain campaign could tilt the balance."

Image source, Getty Images

Sterling jumped briefly past $1.24 for the first time in more than three weeks after the Supreme Court ruled the government must seek parliamentary approval to begin the formal process of leaving the European Union.

The pound rose by just under a full cent to $1.2450 before retreating on signs that, as many in markets had expected, the government could appeal the ruling at a hearing in early December.

Press Association data journalist Ian Jones tweets:

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Among the people who brought the challenge was London businesswoman Gina Miller who argued that the inevitable consequence of invoking Article 50 was the loss of statutory rights enjoyed by UK and EU citizens.

In a statement outside the Royal Courts of Justice, she said:

Ms Miller said her team were "absolutely delighted that we have been able to be part of this debate and bring some sobriety as we go forward".

"The judgement I hope when it's read by the government, and they contemplate the full judgement, that they will make the wise decision of not appealing but pressing forward and having a proper debate in our sovereign parliament, our mother of all parliaments that we are so admired for around the world.”

Former Liberal Democrat leader Lord Menzies Campbell said the ruling was a "slap in the face" for Prime Minister Theresa May.

"This is a clear illustration of the well-known legal principle that no matter how high you are, the law is above you," he said.

"It is a slap in the face for the government. It shows the dangers of playing ducks and drakes with the constitution and particularly the sovereignty of Parliament." 

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Former justice minister and Leave campaigner Dominic Raab says he doesn't think the High Court verdict is going to stop Brexit.

He described the High Court as opening a can of worms and he hopes the Supreme Court will put a lid back on it.

He says the public will take a very dim view of any attempts to frustrate the result of the EU referendum.