Following the UK’s signing of the Lisbon treaty, there is now only one way for Britain to leave the EU. That is to invoke Article 50 of the Lisbon Treaty.
Article 50 of the Lisbon treaty states:
- 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. That agreement shall be negotiated in accordance with Article 218(3) of the Treaty on the Functioning of the European Union. It shall be concluded on behalf of the Union by the Council, acting by a qualified majority, after obtaining the consent of the European Parliament.
- 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 the purposes of paragraphs 2 and 3, the member of the European Council or of the Council representing the withdrawing Member State shall not participate in the discussions of the European Council or Council or in decisions concerning it. A qualified majority shall be defined in accordance with Article 238(3)(b) (see below) of the Treaty on the Functioning of the European Union.
- If a State which has withdrawn from the Union asks to re-join, its request shall be subject to the procedure referred to in Article 49.
Article 238(3) states:
 As from 1 November 2014 and subject to the provisions laid down in the Protocol on transitional provisions, in cases where, under the Treaties, not all the members of the Council participate in voting, a qualified majority shall be defined as follows:
(a) A qualified majority shall be defined as at least 55% of the members of the Council representing the participating Member States, comprising at least 65% of the population of these States.
A blocking minority must include at least the minimum number of Council members representing more than 35% of the population of the participating Member States, plus one member, failing which the qualified majority shall be deemed attained;
(b) By way of derogation from point (a), when the Council does not act on a proposal from the Commission or from the High Representative of the Union for Foreign Affairs and Security Policy, the qualified majority shall be defined as at least 72% of the members of the Council representing Member States comprising at least 65% of the population of these States.
In accordance with section 1 of Article 50 of the Lisbon Treaty, Britain has chosen to leave the EU following a national referendum on 23rd June 2016. A day being dubbed by some as Britain’s Independence Day.