Article 50 of the Lisbon Treaty

Prime Minister May is to officially trigger Article 50 of the Lisbon Treaty today, Wednesday 29 March. Brexit has caused much controversy since Britain voted to leave the Union in a referendum that took place in June 2016. The Article itself is very brief in nature, covering just the basics of exit procedures if a member state should decide to leave the Union. The UK and the remaining member states must negotiate and conclude an agreement, a feat never attempted until now.

 Article 50 of the Lisbon Treaty

1. Any Member State may decide to withdraw from the Union in accordance with its own  constitutional requirements.
2. 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.
3. 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.
4. 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) of the Treaty on the Functioning of the European Union.

5. If a State which has withdrawn from the Union asks to rejoin, its request shall be subject to the procedure referred to in Article 49.

Once Article 50 of the Lisbon Treaty has been triggered, formal negotiations between Britain and the remaining member states can begin; the negotiations are expected to last for up to two years. After this period, regardless of whether favourable terms are agreed, the treaties that govern EU membership will no longer apply to the UK.