Theresa May, the United Kingdom’s Prime Minister will invoke Article 50 which will kickstart the process to leave the United Kingdom on the 29 March 2017. The first ever invocation of Article 50 of the Treaty on European Union will be by the United Kingdom, after the Leave vote in the 2016 referendum on the United Kingdom’s membership of the European Union. When David Cameron resigned in June 2016, he stated that the next Prime Minister should activate Article 50 and begin negotiations with the EU.

There is dispute over whether the decision to invoke Article 50 is the prerogative of the government, as the Cameron government argued, or whether it requires Parliamentary approval. Article 50 states that “Any Member State may decide to withdraw from the Union in accordance with its own constitutional requirements”. However, the Constitution of the United Kingdom is unwritten and the meaning in UK law of the phrase “its own constitutional requirements” is untested. The law firm Mishcon de Reya announced that it had been retained by a group of clients to challenge the constitutionality of invoking Article 50 without Parliament debating it. However, Parliament will be able to vote on any new treaty arrangements that emerge from any withdrawal deal that is reached, though rejecting such a deal (or the failure to reach such a deal) would not stop the withdrawal process once Article 50 is activated.

The referendum was not legally binding on the government: under the principle of parliamentary sovereignty, government and parliament can choose to ignore the result. If the government decides to leave the EU by invoking Article 50 of the Treaty on European Union, it will have to decide when to do so. Withdrawal from the European Union using Article 50 is an untested procedure with some complexity. In a discussion of this topic, The Guardian provided specifics as to the likely method.

“It is entirely up to the departing member state to trigger article 50, by issuing formal notification of intention to leave: no one, in Brussels, Berlin or Paris, can force it to. But equally, there is nothing in article 50 that obliges the EU to start talks – including the informal talks the Brexit leaders want – before formal notification has been made. ‘There is no mechanism to compel a state to withdraw from the European Union,’ said Kenneth Armstrong, professor of European law at Cambridge University…. ‘The notification of article 50 is a formal act and has to be done by the British government to the European council,’ an EU official told Reuters.”

Cameron made it clear that his successor as Prime Minister should activate Article 50 and begin negotiations with the EU.[3] Among the candidates for the Conservative Party leadership election there were disagreements about when this should be: Theresa May said that the UK needs a clear negotiating position before triggering Article 50, and that she would not do so in 2016, while Andrea Leadsom said that she would trigger it as soon as possible