Conferences of representatives of the governments of the member states are convened to discuss and agree EU treaty changes. These meetings are also known as 'intergovernmental conferences' (IGCs).
Before the entry into force of the Lisbon Treaty in 2009, this was the only procedure for treaty revision. It is now called the 'ordinary revision procedure'.
Recent intergovernmental conferences
Innovations in the Lisbon Treaty
The IGC launched by the European Council in June 2007 was tasked with drafting a reform treaty that would enhance the efficiency and democratic legitimacy of the enlarged Union, as well as the coherence of its external action'.
The conference led to the adoption of the Lisbon Treaty, which entered into force on 1 December 2009.
Following the entry into force of the Lisbon Treaty, the Treaty on European Union, the Treaty on the Functioning of the European Union and the Treaty establishing the European Atomic Energy Community were consolidated.
The IGC launched in October 2003 discussed the "draft Treaty establishing a Constitution for Europe" which had been prepared by the European Convention.
The constitution, which was signed by EU leaders in October 2004, was meant to replace all existing treaties with one text.
It was not ratified by all EU countries and did not enter into force.
Revision of EU treaties
Ordinary revision procedure
It allows any member state, the Commission or the European Parliament to submit a proposal for treaty change to the Council which, in turn, presents it to the European Council. National parliaments are notified.
If a majority of member states in the European Council are in favour of examining a proposal for treaty change, the president of the European Council convenes a 'convention'. The European Parliament and the Commission are consulted beforehand. The European Central Bank is consulted if monetary matters are concerned.
The convention, which brings together representatives of national parliaments, heads of state or government, MEPs and the European Commission, discusses the draft treaty changes. Its recommendations, which are adopted by consensus, then go to the IGC.
Alternatively, if the proposed changes do not justify a convention, the European Council - with the consent of the European Parliament - can vote by a simple majority not to organise one and can set its own terms for the IGC.
The IGC, convened by the President of the European Council, decides treaty changes unanimously.
Simplified revision procedure
The Treaty of Lisbon introduced a fast-track procedure to amend the EU's policies and internal actions, known as the 'simplified revision procedure'. It requires no convention or IGC.
The changes are agreed unanimously by the European Council after consulting the European Parliament and the Commission. The European Central Bank is consulted if the changes concern monetary matters.
The decision does not enter into force until it is approved by all member states.
This procedure cannot be used to increase EU powers.
The ordinary legislative procedure
This decision-making procedure is used for around 85 EU policy areas
Special legislative procedures
There are 2 'special legislative procedures': consent and consultation.
The so-called 'passerelle clauses' allow the European Council to replace unanimous voting in the Council of the European Union with qualified majority voting in certain policy areas.
The European Council can also decide to move some policy areas from the special legislative procedure to the ordinary legislative procedure, known as 'codecision', in which the Council of the European Union co-legislates with the European Parliament.
In both cases, the European Council acts unanimously and with the consent of the European Parliament. National parliaments can veto decisions within 6 months, thus preventing them from entering into force.
Additionally, a limited number of treaty provisions can be revised following other procedures.