The UK can unilaterally revoke Brexit, the European Court of Justice ruled on Monday.
The Luxembourg-based court said the UK can revoke the article 50 withdrawal process without needing approval from every other member state.
“The United Kingdom is free to revoke unilaterally the notification of its intention to withdraw from the EU,” the ECJ said.
The ECJ’s ruling is expected to boost the campaign for a second EU referendum on Brexit as it would allow the UK to keep all its previous opt-outs and financial rebate.
The European court said that it should remain the sovereign right of a member state to cancel its withdrawal application before it came into force, in the same way it had a right to start the withdrawal process.
The judges said the European commission had no right to block a decision by the UK to abandon the Brexit process, since that amounted to the EU forcing a member state to leave against its will.
The court said: “The revocation by a member state of the notification of its intention to withdraw reflects a sovereign decision to retain its status as a member state of the European Union, a status which is neither suspended nor altered by that notification.”
A cross-party group of Scottish parliamentarians, including MEPs had been seeking a ruling through the courts.
Monday’s ruling marks the conclusion of a lengthy legal process - which has been fought by the UK Government - that began over a year ago in the Scottish Court of Session. The decision will be reviewed urgently by Scotland’s civil court in Edinburgh.
“When MPs vote on Theresa May’s Brexit deal, they now know they can ultimately choose to stop Brexit and keep the best deal we currently have as a full member of the EU” Scottish Labour MEP, Catherine Stihler
The verdict comes a day before MPs in the UK’s House of Commons are due to hold a vote on British Prime Minister Theresa May’s Brexit withdrawal deal.
Many expect May to lose the vote, plunging the UK, according to May, into unchartered territory.
On Monday, Catherine Stihler, a Labour MEP for Scotland, reacted by saying, “This historic ruling paves the way for the disastrous Brexit process to be brought to a halt.”
“We now know, beyond any doubt, that Westminster can revoke its withdrawal from the European Union.
“This has been a lengthy and expensive legal process, but the result proves that it was worthwhile.
“When MPs vote on Theresa May’s Brexit deal, they now know they can ultimately choose to stop Brexit and keep the best deal we currently have as a full member of the EU.”
"Today's ruling sends a clear message to UK MPs ahead of tomorrow's vote that there is a way out of this mess. A light at the end of the tunnel for the economy, for jobs and for the UK's standing on the world stage. Now it's up to the UK” Scottish National Party MEP, Alyn Smith
She said, “I am increasingly confident that is what will happen if MPs agree to a People’s Vote, which is what the country now urgently needs.”
Further reaction came from Scottish Nationalist MEP Alyn Smith, a co-litigant on the case.
He said, "Today's ruling sends a clear message to UK MPs ahead of tomorrow's vote that there is a way out of this mess. A light at the end of the tunnel for the economy, for jobs and for the UK's standing on the world stage. Now it's up to the UK.”
"If the UK chooses to change their minds on Brexit, then revoking Article 50 is an option and the European side should make every effort to welcome the UK back with open arms."
The UK government played down the significance of the decision, with the country’s Brexit supporting environment minister Michael Gove saying “We don’t want to stay in the European Union. We voted very clearly – 17.4 million people sent a clear message that they wanted to leave the European Union. And that also means leaving the jurisdiction of the European court of justice.”
The ECJ judges rejected arguments from both the UK government and the European commission that article 50, the two-year-long process that triggers a member state’s departure from the EU, could not be revoked unilaterally.
A spokeswoman for the court said that any revocation “must be decided following a democratic process in accordance with national constitutional requirements”.