European Court of Justice’s advocate general said today that UK has the right to withdraw Brexit notice unilaterally, up to the point of formal conclusion of the deal. ECJ usually follow the advocate general’s opinions in its final rulings even though they’re not binding.
To be more exact, ECJ said “Advocate General (Manuel) Campos Sanchez-Bordona proposes that the Court of Justice should declare that Article 50 … allows the unilateral revocation of the notification of the intention to withdraw from the EU”. And, “That possibility continues to exist until such time as the withdrawal agreement is formally concluded.”