The advocate general of the European Union’s top court will give his opinion on Dec. 4 as to whether Britain can unilaterally reverse Brexit, the court said on Wednesday.

The European Court of Justice (ECJ) held an urgent hearing in a case about whether Britain can revoke its notice to withdraw from the EU under Article 50 of the Lisbon Treaty without agreement of the other 27 states.

The ECJ said Advocate General Manuel Campos Sánchez-Bordona, whose advice is usually followed by judges, would deliver his decision on Dec. 4.

That is the same day that the British parliament is due to begin a five-day debate on Prime Minister Theresa May’s draft divorce bill before members of parliament vote on Dec. 11.

Britain is due to exit the EU on March 29, two years after London served notice in line with a June, 2016 vote to leave, but the fate of Brexit remains up in the air.

Many in May’s Conservative Party as well as opposition MPs have said they will vote her deal down, raising the prospect of Britain leaving the bloc without any agreement.

The Scottish politicians behind the ECJ case hope that if the court rules in their favour, it would pave the way for a potential second referendum, giving voters the option to remain in the EU.

May has ruled out any second vote and the lawyer for the British government called on the ECJ not to get involved in domestic politics and to dismiss the case as hypothetical.

Both the European Commission and the Council of the European Union accepted that Article 50 could be revoked, but they argued that it could only be done with the unanimous permission of the remaining EU states.

No date has yet been given for the decision of the Luxembourg justices although the court said it would come quickly. While the advocate general’s opinion is non-binding, his advice is usually followed in the majority of cases.