The Treaty was signed on 29 October 2004 by representatives of the then 25 member states of the European Union. It was later ratified by 18 member states, which included referendums endorsing it in Spain and Luxembourg. However the rejection of the document by French and Dutch voters in May and June 2005 brought the ratification process to an end.
Following a period of reflection, the Treaty of Lisbon was created to replace the Constitutional Treaty. This contained many of the changes that were originally placed in the Constitutional Treaty but was formulated as amendments to the existing treaties. Signed on 13 December 2007, the Lisbon Treaty entered into force on 1 December 2009.
The drafting for European Constitution began in a call for a new debate on the future of Europe at the Laeken European Council in December 2001. A European Convention was founded shortly afterward which was chaired by former French President Valéry Giscard d'Estaing and composed of two Members of Parliament (generally one from the governing majority and one from the opposition) of each Member State and applicant state, 16 MEPs, 2 members of the European Commission and a representative from each government. It met in public. Giscard d'Estaing proposed to draft a Constitution. Romano Prodi, the President of the European Commission backed a draft text, called the 'Penelope Project', which contained a deeper integration of the countries and a clearer institutional model.
After protracted negotiations in the Intergovernmental Conference (IGC) during the Italian presidency, disputes arose over the proposed framework for qualified majority voting: the final text of the TCE was settled in June 2004 under the Irish presidency.
The Treaty establishing a Constitution for Europe was signed in Rome on 29 October 2004 by 53 senior political figures from the 25 member states of the European Union. In most cases heads of state designated plenipotentiaries to sign the treaty, but some presidents also signed on behalf of states which were republics. Most designated plenipotentiaries were prime ministers and foreign ministers.