Though ratified by a majority of the Member States, the Constitutional Treaty failed to enter into force. Following its rejection in referenda in France and the Netherlands on 29 May and 1 June 2005 respectively the ratification process continued in some Member States, but others put planned parliamentary debates and referenda on ice. Faced with this institutional crisis, the European Council, meeting on 16–17 June 2005, called for a year-long ‘period of reflection’. Eventually, a way out of the crisis was found under the German Presidency, when the European Council, in June 2007, agreed on a detailed mandate for an Intergovernmental Conference to draft a 'Reform Treaty' incorporating many of the provisions of the now officially abandoned Constitutional Treaty, but dropping its most controversial features. The Intergovernmental Conference concluded its work under the Portuguese Presidency, reaching agreement on the text of the Reform Treaty and its annexed Protocols and Declarations on 18 October 2007. The new Treaty was subsequently signed in Lisbon on 13 December 2007.

At that time it was hoped that all 27 Member States would ratify the Treaty of Lisbon, as it is officially entitled (the term 'Reform Treaty' was dropped), in accordance with their national constitutional requirements by the end of 2008 to enable it to come into force before the European Parliament elections in mid-2009. However, the Irish no vote on 12 June 2008 – Ireland was the only Member State to supplement its parliamentary ratification procedure with a national referendum – has created great uncertainty about the future of the Lisbon Treaty.

Nevertheless, hope about the Treaty’s future re-emerged at the European Council in December 2008 where Ireland committed itself to seek ratification of the Lisbon Treaty by November 2009 in return for concessions from the EU leaders to Ireland in order to address the major concerns that surfaced in the referendum debate. One of the concessions made by the European Council is that it will take the decision that the Commission will continue to include one national of each Member State (beyond 2014). Of course, it remains to be seen whether the Irish people will vote ‘yes’ and enable the Irish government to ratify the Lisbon Treaty.