Lisbon Treaty
Supporters of the EU's Lisbon Treaty celebrating in Dublin after Irish voters overwhelmingly approved the measure, October 2009.
Lisbon Treaty
European Union
Also known as: Reform Treaty
Lisbon Treaty, international agreement that amended the Maastricht Treaty, Treaties of Rome, and other documents to simplify and streamline the institutions that govern the European Union (EU). Proposed in 2007, the Lisbon Treaty was ratified by most member states in 2008, but a referendum in Ireland—the only country that put the Lisbon agreement to a public vote—rejected it on June 12, 2008, thus jeopardizing the entire treaty. More than a year later, on October 2,...