Given the social, political, economic and constitutional significance of triggering Article 50 of the Lisbon Treaty, which starts the process of withdrawal from the European Union, it is comforting that Theresa May has indicated that she will not do so until 2017 at the earliest. On the day after the referendum, Jeremy Corbyn, the Labour leader, said that Article 50 should be invoked immediately. But had then-Prime Minister David Cameron followed this advice he would have set in motion a process for which the government was unprepared. He might also have been acting unlawfully. Here’s why.
Starting the Article 50 process involves two steps. First, a member state must make the decision to withdraw from the EU “in accordance with its own constitutional requirements.” Second, that decision must be notified to the EU Council. However, if a decision is not taken in accordance with these “constitutional requirements,” then the notification will be unlawful. What, then, are the constitutional requirements of the UK? A fierce debate has erupted around this question, to which there is no ready answer.