Revista Temas de Derecho Constitucional

335 La cuestión preliminar del TJUE sobre la revocatoria del brexit: fortaleciendo el derecho constitucional de la unión europea. 5.5. Article 50 TEU through the looking glass: The conditions for the exercise of the revocation In terms of the revocation of the notice to withdraw, there are aspects to be taken into account: conditions, timing and effect. In terms of the conditions for the exercise of the unilateral right of revocation, the Advo- cate General’s Opinion Opinion relied on the principles of good faith and sincere coop- eration (Article 4(3) TEU) to determine substantive conditions and limits on the exercise of revocation. 85 The Court did not add further substantive conditions. However, the Court addressed other further limitations imposed by EU law as the notification of revo- cation must be ‘unequivocal and unconditional, that is to say that the purpose of that revocation is to confirm the EU membership of the Member State concerned’. 86 As regards the constitutional requirements that should be fulfilled for such a revoca- tion are a matter of domestic constitutional law. Guidance is provided by the ECJ in its statement that a notice in writing addressed to the European Council must only be provided after the Member State has fulfilled the constitutional requirement in deciding to revoke. In the UK, it is unclear whether this would require a new Act of Parliament explicitly authorising the power to revoke before a notification, or the Prime Minister is already vested in such a power pursuant to the EU (Notification) Act 2017. With regard to the timing for the exercise of the right, the judgment confirms that a revocation may be exercised at any point before the Withdrawal Agreement comes into force which is different from the Advocate General’s opinion which pointed at the date in which the Agreement is formally concluded . As for the formality of the revocation, this has to take place in an unequivocal and un- conditional manner, by a notice addressed to the European Council in writing, after the Member State concerned has taken the revocation decision in accordance with its con- stitutional requirements. The purpose of that revocation is to confirm the EU member- ship of the Member State concerned under terms that are unchanged as regards its sta- tus as a Member State, and that revocation brings the withdrawal procedure to an end. The Court interpreted Article 50 TEU as meaning that, where a Member State has noti- fied the European Council, in accordance with that article, of its intention to withdraw from the European Union, it allows that Member State — for as long as a withdrawal agreement concluded between that Member State and the European Union has not en- tered into force or, if no such agreement has been concluded, for as long as the two-year period laid down in Article 50(3) TEU, possibly extended in accordance with that para- graph, has not expired — to revoke that notification unilaterally. In sum, the right to revert the withdrawal can be exercised for as long as a withdrawal agreement concluded between the European Union and that Member State has not en- tered into force or, if no such agreement has been concluded, for as long as the two-year period laid down in Article 50(3) TEU, possibly extended in accordance with that provi- 85 Judgment, para 148. 86 Judgment, para para 75.