The Treaty of Lisbon is one of the most significant constitutional reforms in the history of the European Union (EU). Signed on 13 December 2007 in Lisbon, Portugal, and entering into force on 1 December 2009, the treaty modernized the EU’s institutional framework to meet the demands of an enlarged 27-member Union. By amending the Treaty on European Union (TEU) and the Treaty establishing the European Community (TEC), it strengthened democratic legitimacy, streamlined decision-making, enhanced transparency, and improved the EU’s role in global affairs. The treaty also replaced key provisions of the Treaty of Nice (2001) while preserving many reforms originally proposed in the failed European Constitution (2004).
This article provides a comprehensive overview of the Treaty of Lisbon, covering its historical background, objectives, institutional reforms, permanent President of the European Council, High Representative for Foreign Affairs, strengthening of the European Parliament, double-majority voting system, legally binding Charter of Fundamental Rights, Citizens’ Initiative, subsidiarity principle, EU legal personality, competence classification, Article 50 (Brexit), achievements, criticisms, and long-term significance. Whether you are preparing for UPSC, State PCS, UGC-NET Political Science, International Relations, European Studies, International Law, Public Administration, or Competitive Examinations, this guide offers a clear, engaging, and exam-oriented understanding of one of the most influential treaties shaping the modern European Union.
Author: Darshita Neeraj
Senior Researcher,
Mudita Learning and Knowledge Private Limited
Email: info@muditabooks.com
Date of post: 30.07.2026
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