Britain can unilaterally halt the formal process of leaving the European Union, the bloc's top court said Monday.
The European Court of Justice sided with the advice of its top legal officer, who declared last week that the UK has the power to withdraw its notification to leave the EU under Article 50 of the Lisbon Treaty without the agreement of other member states.
The UK can withdraw its Article 50 notification before the withdrawal agreement negotiated by the UK and the EU comes into force, the ECJ said. "The United Kingdom is free to revoke unilaterally the notification of its intention to withdraw from the EU," the court ruled.
Crucially, the UK would be able to retain its current agreements with the EU, which include a rebate on financial contributions, an opt-out to the Schengen open-border zone and non-membership of the Euro.
"Such a revocation, decided in accordance with its own national constitutional requirements, would have the effect that the United Kingdom remains in the EU under terms that are unchanged as regards its status as a Member State," the court said.
Pressure mounts on May as vote looms
The fast-tracked judgment came a day before the House of Commons is due to vote on British Prime Minister Theresa May's Brexit deal, a vote she is widely predicted to lose heavily.
May has always said her government would not reverse the decision to leave the EU. But should she lose the vote, and her government collapsed, the decision gives the UK parliament another way out of the Brexit process.
Britain's Environment Secretary, Michael Gove, told the BBC that the UK would leave the EU whatever the ECJ ruled. "We voted very clearly -- 17.4 million people sent a clear message that they wanted to leave the European Union," said Gove, a prominent Leave campaigner. "And that also means leaving the jurisdiction of the European Court of Justice," he said.
European Council President Donald Tusk said he had spoken to May on Sunday ahead of what he described as an "important week for the fate of Brexit."
Also on Sunday, former UK Foreign Secretary Boris Johnson said May should go back to Brussels and renegotiate the deal in the event she loses on Tuesday.
Speaking on the BBC's Andrew Marr show, Johnson criticized the current deal, describing it as a "legal lobster pot" reducing the UK to "colony status" at the hands of the EU. Johnson dismissed a "Norway solution" (which would allow for closer trading ties with the bloc) and a second referendum as both having "grave, grave defects."
The ECJ case, brought by pro-Remain campaigners in Scotland, was fiercely opposed by the British government, which unsuccessfully argued that the Supreme Court in London should intervene before the case went to Europe.
It will now be referred back to Scotland's top court, Court of Session in Edinburgh, for a final decision.