Treaty of Lisbon
Treaty modifying the constitutional basis of the European Union, signed by all the States of the Union in Lisbon on 2007
The Treaty of Lisbon (initially known as the Reform Treaty) is a European agreement that amends the two treaties which form the constitutional basis of the European Union (EU). The Treaty of Lisbon, which was signed by all EU member states on 13 December 2007, entered into force on 1 December 2009. It amends the Maastricht Treaty (1992), known in updated form as the Treaty on European Union (2007) or TEU, as well as the Treaty of Rome (1957), known in updated form as the Treaty on the Functioning of the European Union (2007) or TFEU. It also amends the attached treaty protocols as well as the Treaty establishing the European Atomic Energy Community (EURATOM).
Prominent changes included the move from unanimity to qualified majority voting in at least 45 policy areas in the Council of Ministers, a change in calculating such a majority to a new double majority, a more powerful European Parliament forming a bicameral legislature alongside the Council of Ministers under the ordinary legislative procedure, a consolidated legal personality for the EU and the creation of a long-term president of the European Council and a High Representative of the Union for Foreign Affairs and Security Policy. The Treaty also made the Union's bill of rights, the Charter of Fundamental Rights, legally binding. For the first time, the treaty gave member states the explicit legal right to leave the EU, and established a procedure by which to do so.
The stated aim of the treaty was to "complete the process started by the Treaty of Amsterdam (1997) and by the Treaty of Nice (2001) with a view to enhancing the efficiency and democratic legitimacy of the Union and to improving the coherence of its action". Opponents of the Treaty of Lisbon, such as former Danish Member of the European Parliament (MEP) Jens-Peter Bonde, argued that it would centralize the EU, and weaken democracy by "moving power away" from national electorates. Supporters argue that it brings more checks and balances into the EU system, with stronger powers for the European Parliament and a new role for national parliaments.
Negotiations to modify EU institutions began in 2001, resulting first in the proposed Treaty establishing a Constitution for Europe, which would have repealed the existing European treaties and replaced them with a "constitution".
The public source identifies “Treaty of Lisbon” as treaty modifying the constitutional basis of the European Union, signed by all the States of the Union in Lisbon on 2007. This brief keeps that definition visible, then builds a research path around Treaty, Lisbon and modifying.
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Chronology, provenance and viewpoint should be read together before a broad social or political interpretation is accepted. The source revision retrieved here is dated Jul 26, 2026. The linked authority identifier is Q52843. VIAF identifies the subject as 176075178. 1 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank. The first chronological checks are 2007, 2009, 1992 and 1957.
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This entry incorporates text from “Treaty of Lisbon” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.