This is the author accepted manuscript. The final version is available from Westlaw UKThe purpose of this paper is to determine whether a Member State of the EU may revoke its notice to withdraw from the Union under art.50 TEU. The answer to this question has significant practical implications for Brexit, both domestically and across Europe. While the reversibility of the British withdrawal notification has taken centre stage in the debate on Brexit, the matter has not been assessed in depth. The present paper suggests that interpreting art.50 TEU with reference to art.31 and art.32 of the Vienna Convention on the Law of Treaties permits a more systematic analysis of the subject than what has been offered so far by commentators and the Eng...