The Treaty of Lisbon was signed on December 13, 2007, in Lisbon, Portugal, by representatives of the then 27 member states of the European Union. This treaty served to amend both the Treaty of Rome, which established the European Communities, and the Maastricht Treaty, which laid the foundation for the European Union itself. The impetus for this reform was prompted by the need for an updated governance framework following the 2005 French and Dutch referendums that rejected the proposed EU Constitution. The Treaty of Lisbon aimed to simplify decision-making processes and to enhance the accountability and visibility of the Union on the global stage.

One significant development was the introduction of the position of a permanent President of the European Council, whose role is to foster cohesion and represent the EU externally, along with the creation of the High Representative of the Union for Foreign Affairs and Security Policy. This was seen as a step towards more cohesive and effective foreign policy. The treaty also expanded the legislative powers of the European Parliament, granting it equal footing with the Council in many areas, thus making decision-making more democratic. The legal personality of the EU was established, enabling it to enter treaties and be part of international organizations more effectively.

Despite concerns over legitimacy and effectiveness in governance, the Treaty of Lisbon was portrayed as a vital step toward a more united and efficient Europe. The treaty came into force on December 1, 2009, transforming how the EU operates and setting the groundwork for future integration efforts. It not only reformed the institutional framework but also addressed key areas such as human rights, energy policies, and environmental concerns, ensuring that these topics were integral to the EU’s agenda moving forward.