At the time of writing – less than 3 weeks until the current ‘Brexit day’ of 31 October 2019 – all options relating to the UK’s departure from the European Union appear to be on the table. Leaving with a deal, ‘crashing out’, not leaving at all, or anything in between seem equally possible. Much attention has been paid to the UK’s constitutional requirements governing the executive’s actions in relation to Brexit, as well as the domestic legal consequences of flouting them. The possibility of Prime Minister Johnson going to jail for violating these requirements has even been considered. However, not much has been said about the potential international law consequences. Here I explore whether international law could prevent a No-Deal Brexit – or, more precisely, whether a failure to comply with domestic constitutional requirements may prevent the UK’s withdrawal from the EU from taking effect in international law. This discussion draws on my recent work exploring the role of domestic law in the international legal validity of treaty withdrawal more generally.
The starting point for this discussion is Article 50 of the Treaty on European Union (TEU) – by now, likely the most famous treaty exit clause in legal history. Art 50 states, in part:
Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements.
A Member State which decides to withdraw shall notify the European Council of its intention. In the light of the guidelines provided by the European Council, the Union shall negotiate and conclude an agreement with that State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the Union. …
The Treaties shall cease to apply to the State in question from the date of entry into force of the withdrawal agreement or, failing that, two years after the notification referred to in paragraph 2, unless the European Council, in agreement with the Member State concerned, unanimously decides to extend this period.
For our purposes, Art 50(1) is the key provision. This, unusually, makes the triggering of withdrawal from the EU explicitly contingent on compliance with the State’s domestic constitutional requirements. Thus, in principle, if there is a failure to comply with those constitutional requirements, the decision to withdraw is invalid according to the TEU. In the 2018 Wightman decision, the ECJ affirmed that “the decision to withdraw is for that Member State alone to take, in accordance with its constitutional requirements, and therefore depends solely on its sovereign choice” (at para. 50).
While a full dissection of the UK’s constitutional requirements for leaving the EU is not possible here, there are two clear domestic law limitations constraining the UK executive’s prerogative in relation to Art 50. Read the rest of this entry…