The purpose of this paper is to determine whether a Member State of the EU may revoke its notice to withdraw from the Union under Article 50 TEU. The answer to this question has significant legal and political implications for the relationship between the Member States and the EU. More urgently, it also has significant practical implications for the withdrawal of the UK from the Union. While the reversibility of the UK’s impending notice to leave has taken centre stage in the debate on Brexit, the matter has not been assessed in depth. The present paper offers a systematic analysis of Article 50 TEU based on the applicable rules of interpretation. It demonstrates that the text and context of Article 50 TEU, the general scheme of the Treaties, other rules of international law and the relevant preparatory work all confirm that a notice to withdraw is in fact reversible. The Supreme Court should therefore revisit and overrule the High Court’s decision on this point in Miller. Since a systematic interpretation of Article 50 TEU leaves no scope for reasonable doubt about its meaning, the Supreme Court may do so without having to refer the question to the Court of Justice of the European Union.