The European Court of Justice (ECJ) advocate general Manuel Campos Sanchez-Bordona rejected the contention that Article 50 only allows the possibility of revocation following a unanimous decision of the European Council.
Instead, he said Article 50 allows the “unilateral revocation of the notification of the intention to withdraw from the EU, until such time as the Withdrawal Agreement is formally concluded”.
But the Prime Minister's official spokesman told reporters in Westminster "this is not a final judgment" and "it does nothing in any event to change the clear position of the Government that Article 50 is not going to be revoked".
A full ruling is expected in the coming days and could be issues before the Commons votes on Theresa May’s Brexit deal on 11 December.
Responding to the opinion Catherine Stihler, the Labour MEP for Scotland and a member of the group involved in the legal process, said: “There is now light at the end of the tunnel."