Overview[]
The Treaty of Lisbon (or Lisbon Treaty) (initially known as the "Reform Treaty") is an international agreement that amends the two treaties which form the constitutional basis of the European Union (EU). The Lisbon Treaty was signed by the EU member states on December 13, 2007, and entered into force on December 1, 2009. It amends the Maastricht Treaty (also known as the Treaty on European Union) and the Treaty establishing the European Community (TEC) (also known as the Treaty of Rome). In this process, the Treaty of Rome was renamed to the Treaty on the Functioning of the European Union (TFEU).