On December 10, 2018, the Court of Justice of the European Union ruled that the U.K. is able to unilaterally revoke its notice of intention to withdraw from the EU. Any such revocation could only be made before the draft Withdrawal Agreement entered into force or, if there is no agreement, expiration of the two-year period since the withdrawal notification was made or any extension of that two-year period in accordance with Article 50 of the Treaty on the European Union. The revocation could also only be made after a revocation decision was made by the U.K. according to its constitutional requirements.
The CJEU decision means that the U.K. Parliament has three options to consider on Brexit: remain in the EU, accept the draft withdrawal agreement negotiated by the U.K. Government or leave the EU on March 29, 2019, without an agreement (known as a "hard Brexit").
The Court of Session referred the question of whether the U.K. can unilaterally revoke its notice of withdrawal from the EU on September 21, 2018. It remains for the Scottish Court to issue a declaratory judgment on this topic, based on the CJEU's ruling, on the legal position—Wightman v Secretary of State for Exiting the European Union [2018] CSIH 62.
To effect revocation, the U.K. would need to provide an unequivocal and unconditional written notice to the European Council. Revocation of the Brexit notice would mean that the U.K. would remain in the EU as a member state and the withdrawal process would end.
The CJEU ruling is available at: http://curia.europa.eu/juris/document/document.jsf?text=&docid=208636&pageIndex=0&doclang=EN&mode=lst&dir=&occ=first∂=1&cid=1186545 , the CJEU press release is available at: https://curia.europa.eu/jcms/upload/docs/application/pdf/2018-12/cp180191en.pdf and details of the Scottish Court's reference is available at: https://finreg.shearman.com/scottish-court-says-court-of-justice-of-the-europ .
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