LUXEMBOURG, Nov 27 (Reuters) - Britain can unilaterally reverse its decision to leave the European Union, Europe's top court was told on Tuesday at an urgent hearing in a case supporters of membership hope could pave the way to a second referendum and ultimately stop Brexit.
Britain is due to exit the world's biggest trading bloc on March 29 but it remains unclear whether British Prime Minister Theresa May's draft divorce deal agreed with the EU on Sunday will be passed by parliament on Dec. 11.
Aidan O'Neill, lawyer for the Scottish politicians told a hearing of a full court of Luxembourg justices who have expedited the case because of its urgency, said all parties agreed that Article 50 could be revoked.
"The petitioners' case is that it's fundamental to the treaties and values of the European Union that a member state can revoke a withdrawal notice from the European Union without agreement of all other council states," O'Neill said.
O'Neill told the court those behind the case needed to know what their options were before imminent legislative votes.
That latter statement has given added significance to the outcome of Tuesday's case at the ECJ - whose supremacy over UK legal matters May has cited as one reason to leave the EU.
If the ECJ concludes Britain can unilaterally reverse Brexit, it could give British lawmakers (MPs) a third viable option as an alternative to May's deal or what ministers describe as a chaotic no deal scenario - staying in the bloc after another referendum.