The Government is facing a High Court challenge over the legality of Article 50, in a case it is claimed could bring Brexit negotiations to a halt.
A judicial review being filed in the High Court on Friday contends the UK never made the constitutional decision to leave the EU.
Campaigners argue the referendum result was not ratified by an act of Parliament, which they claim means the triggering of Article 50 is invalid.
While the wording of the European Union (Notification of Withdrawal) Act 2017 gave Theresa May the authority to trigger Article 50, activists say the act does not explicitly state that Parliament makes the decision to leave the bloc.
In an earlier case brought by Gina Miller, the Supreme Court established the referendum result was not a constitutionally binding decision to leave the EU and that only an act of Parliament could make that decision.
Campaigners bringing the case to the High Court claim if they are successful, the Article 50 notification could be nullified and negotiations halted until Parliament votes on an act to recognise the referendum result to leave the bloc.
A crowdfunding campaign raised more than £111,000 to launch the legal challenge, with nearly 3,900 people donating to the case.
Elizabeth Webster, a 54-year-old small business owner who ran as a Liberal Democrat candidate for North Swindon in the 2017 General Election, is spearheading the case.
Speaking to The Independent, she said: “We need to get people to see what’s going on. This is not about stopping Brexit, but if we are to leave the EU then it needs to be done in a lawful and orderly way.”
Ms Webster warned that ignoring the proper legal process for Article 50 to be triggered would bring consequences “almost too grave to contemplate”.
She added that any divorce deal and post-Brexit trade deals negotiated with the EU could be struck down if Article 50 was found to be invalid.
“Whether you are for or against Brexit, we believe it is a democratic scandal that the public and Parliament have been misled by Ms May, David Davis and others. It is an abuse of our constitution,” she said.
“If we fudge through this one what will we be fudging through next time?”
Ms Webster said her decision to lead the case was “not taken lightly” and admitted that her family was worried about her security. “I realise that a lot of people are going to be hating me for this,” she said.
The group of activists, led by Ms Webster and represented by Hugh Mercer QC – who chairs the Brexit Working Group of the Bar – and Gwion Lewis, is calling on the courts to make Parliament vote on a new act which would ratify the result of the EU referendum, or call for a second referendum which in turn would be ratified by MPs in the Commons.
The legal argument setting out the alleged invalidity of Article 50 is not new. In an article for Counsel magazine, barrister David Wolchover previously described the letter giving notice of the UK’s intention to leave the EU as “an illusion” and wrote that Ms May’s triggering of Article 50 was a non-event with no legal basis.
Earlier this year, Baroness Eluned Morgan, the Shadow minister for Wales in the House of Lords, said in a plenary session that the Withdrawal Act did not actually notify the EU of the UK’s decision to leave the union.
She warned this “technical flaw” could make it vulnerable to a challenge in court.
Separately, architect Steve Lawrence, who lives between London and Amsterdam, warned Downing Street, Commons Speaker John Bercow, Attorney General Jeremy Wright, the Queen and the European Commission of the risk of the invalidity of the Withdrawal Act, in a series of letters seen by The Independent.
Downing Street’s office confirmed receiving Mr Lawrence’s letters and a petition is also being considered by the European Parliament.
Mr Lawrence, who supports the Article 50 challenge, accused the Government of “using the crown prerogative to circumvent Parliament”.
He told The Independent: “Our parliamentary democracy has been turned upside down. The so-called ‘will of the people’ has been used to beat MPs into submission in passing an act they did not have to pass. This challenge is an attempt to restore our parliamentary democracy.”
The latest legal challenge comes after Ms May faced an embarrassing defeat in the Commons at the hands of Tory rebels with the Government forced to accept changes to its Withdrawal Bill to guarantee Parliament a “meaningful” final vote on any Brexit deal.
Weakened by two departures from her Cabinet in less than two months, Ms May was prepared to climbdown on her promise to enshrine the Brexit date of 29 March 2019 into UK law, shying away from another confrontation with Tory rebels.
The Department for Exiting the European Union said: ”This is a matter for the court. It would not be appropriate for the Government to comment on ongoing proceedings.”
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