The European Court of Justice has confirmed that the UK could unilaterally revoke Article 50, the official legal process required to leave the EU.
Prime minister Theresa May began the process on March 29, 2017, meaning the UK must leave the EU by March 29, 2019.
Late last year, a judicial review of Article 50 was requested by the Scottish parliament and European parliament to determine whether it could be legally revoked before the end of that two-year period without permission from the rest of the EU. This could allow for further negotiations or the UK remaining in the EU.
"The Full Court has ruled that, when a Member State has notified the European Council of its intention to withdraw from the European Union, as the UK has done, that Member State is free to revoke unilaterally that notification," Monday's judgment read.
MPs in the House of Commons are scheduled to vote on May's proposed withdrawal agreement with the EU on Tuesday.
It is expected that the deal will be voted down. Parliament could then follow a number of different courses of action, including backing a Norway-type deal or amendments that make significant changes to the backstop agreement — the insurance policy that prevents a hard border in Ireland.
The defeat would also pave the way to a second referendum on leaving the EU, which has already been discussed in Downing Street. It is unclear whether or not remaining in the EU entirely would be an option on the ballot paper.
Reacting to the ECJ ruling, environment secretary Michael Gove, a lead campaigner for Brexit, insisted that it did not change the UK's intention to leave the EU.
"This case is all very well but it doesn’t alter the very clear indication that 17.4 million people want to leave the EU," Gove told BBC Radio 4's Today programme.
Gove also dismissed the possibility of a second referendum, which campaigners are referring to as a "people's vote".
"It suggests that the first referendum wasn’t a vote by the people," Gove continued.
"It is an attempt by people who never accepted that first vote and that democratic mandate and want to overturn it."
Jo Maugham QC, director of the Good Law Project — the legal team that worked with MSPs to bring the case — welcomed the judgment.
"No one voted for a deal that cuts our freedoms and leaves us worse off with less control," Maugham said in a statement.
"But all the courts can do is open the door to remaining," he continued. "It is up to MPs to remember what they came into politics for. And find the moral courage to put the country's interest before private ambition."
Conservative MP Anna Soubry, who has been at the forefront of the campaign for a second referendum, pointed to a growing number of people who appear to support Remain, according to polls.
"Ignore them at your peril," she tweeted following the announcement of the ECJ's judgment. "We want @peoplesvote_uk on your #Brexit deal w Remain on ballot paper. Now we know the detail ppl have a right to #FinalSay & right to change their mind."
"Brexit is not inevitable," Labour MP Chuka Umunna, who has championed a second referendum, said. "If we hold a #PeoplesVote and decide to keep our current EU deal, the UK can do so!"
Former UKIP leader Nigel Farage, who has long led the campaign for the UK to leave the UK, condemned the judgment. "No surprise there," Farage said. "The collusion to stop Brexit continues."
Liberal Democrat MP and spokesperson on Brexit Tom Brake, who was involved in bringing the legal case to the ECJ, said the judgment should urge the government to drastically rethink Brexit.
"For the sake of people's livelihoods, the Prime Minister must end the uncertainty and rule out a no-deal," Brake said in a statement.
"It is clear any Brexit will make people poorer and reduce the UK's standing in the world.
"MPs should not only vote down Theresa May's deal, but back a People's Vote with the option to remain in the EU."