Article 50 of the Lisbon Treaty binds the European Union (EU). It provides that any member state may withdraw from the EU. Upon notification, the EU shall negotiate and conclude an agreement with the State, setting out the arrangements for its withdrawal, taking account of the framework for its future relationship with the EU. The Treaty shall not apply to the State in question from the date of the withdrawal agreement or, failing that, two years after the notification, unless the European Council unanimously decides to extend the period.
Against the background of these provisions, the British Government called a referendum on continued membership of the European Union (EU) in June, 2016. 51.9 percent voted to leave the EU. After article 50 was triggered, withdrawal was due to take place on 29 March, 2019. Withdrawal was delayed until 31 October, 2019 after two extensions. With her proposed agreements to leave the EU rejected three times by the House of Commons, Theresa May resigned as Leader of the Conservative Party and, after Boris Johnson won the position, she resigned as Prime Minister and Boris Johnson was appointed.