Once the UK Government has handed in to the European Council the notice pursuant to Article 50 (2) of the Treaty on European Union (“TEU”), the exit process provided for in Article 50 TEU will be started and the UK and the EU enter into negotiations in respect of a Withdrawal Agreement and one or more agreements on the future relationship (Future Relationship Agreements) between the UK and EU. The UK would cease to be a Member State of the EU either at the date at which the Withdrawal Agreement enters into force or, if there is not yet a Withdrawal Agreement which has entered into force, two years after the notice pursuant to Article 50 (2) TEU has been received by the European Council. The two years period can be extended by the unanimous consent of all other Member States of the EU within the European Counsel, but in principle only for the purpose of finalizing the Withdrawal Agreement but not for the purpose of entering into the Future Relationship Agreements.
Even before the vote takes place politicians, academics and lawyers are arguing about how certain key aspects of Brexit may work. Apart of the question which constitutional procedure needs to be followed within the UK prior to handing in the notice in Brussels and the controversially discussed question whether the Court of Justice of the European Union would be competent to review compliance with the constitutional provisions applicable within the UK, one distinct other area of legal dispute is what happens if the UK Government or UK Parliament changes its mind about a Brexit during the two year notice period.
For a long time it had been the widely held view across Europe that any termination notice by the UK Government to the European Council cannot be revoked unilaterally since the wording of Article 50 TEU is said to be clear, does not provide for a revocation right and provides that the termination notice kick-starts the two years negotiation period which automatically results in the relevant Member State leaving the EU after such two years unless an extension of the two year period is agreed unanimously and since Article 50 (5) TEU provides that any rejoining of the EU after withdrawal needs to take place pursuant to Article 49 TEU. This view has, for example, been set out in a research paper of the European Parliament published in February 2016.
In contrast to the view proposed in the research paper of the European Parliament, on 4th May 2016 the European Union Committee of the House of Lords issued a report in which it proposes a contrary legal view that a withdrawal notice can be revoked unilaterally during the two years negotiation period. This report is based on a public evidence session which the committee held with Sir David Edward, QC, and Professor Derrick Wyatt, QC.
It should be noted that neither report discusses whether and to what extent Article 68 of the Vienna Convention on the Law of Treaties – which provides that certain notifications which target at ending International Treaties may be revoked at any time before they take effect – could become relevant for the interpretation of Article 50 TEU. In addition neither report considers how Article 50 TEU should be interpreted, in the light of the autonomous approach which the European Court of Justice takes in respect of interpreting European law independent from the individual domestic approaches of EU Member States and which might disregard Article 68 of the Vienna Convention.
In the event that the UK Government actually attempts to withdraw any termination notice rendered to the European Council under Article 50 TEU it would depend on the then prevailing circumstances whether the Court of Justice of the European Union could be called upon to decide whether this is compatible with Article 50 TEU or not. One potential avenue to proceedings in front of the Court could, depending on the circumstances, be Article 263 of the Treaty on the Functioning of the European Union (TFEU) in case of an infringement of the EU Treaties by the Council, the Commission or the European Parliament adopting acts implementing such withdrawal of the termination notice, or, in any event, the Preliminary Ruling proceedings pursuant to Article 267 TFEU in case that the question of whether the UK has actually ceased to be a Member State of the EU or not becomes relevant in any domestic court proceedings (for example commercial disputes) within any of the other 27 Member States of the European Union under any relevant circumstances.