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The Treaty of Nice, agreed by the Heads of State or Government at the Nice European Council on 11 December 2000 and signed on 26 February 2001, is the culmination of eleven months of negotiations that took place during an Intergovernmental Conference (IGC) opened in February 2000. It entered into force on 1 February 2003 after being ratified by the fifteen Member States of the European Union (EU) according to their respective constitutional rules.

The Treaty of Amsterdam made specific provisions for the IGC 2000 in its Protocol on the institutions in the context of EU enlargement. It did in fact anticipate that "at least one year before the membership of the European Union exceeds twenty, a conference of representatives of the governments of the Member States shall be convened in order to carry out a comprehensive review of the provisions of the Treaties on the composition and functioning of the institutions". Furthermore, three Member States, Belgium, France and Italy were also intent on making a Declaration stating that strengthening the institutions was an "an indispensable condition for the conclusion of the first accession negotiations".

The Cologne European Council (June 1999) confirmed the need to convene an IGC to consider the institutional issues which had not been settled in Amsterdam and which had to be resolved before enlargement.

The Helsinki European Council (December 1999) reaffirmed this mandate and decided that the IGC would look at the size and composition of the Commission, the weighting of votes in the Council, the extension of qualified-majority voting, as well as any other institutional adjustments that would have to be made to the Treaties in connection with the above issues and in the context of implementing the Treaty of Amsterdam.

This European Council's conclusions left the option of adding further items to the IGC's agenda, which the Feira European Council (June 2000) took advantage of with the addition of enhanced cooperation.

Preparation for the IGC began in October 1999 when, at the request of the Commission, the group of high level experts led by Mr Dehaene presented its report on the institutional implications of enlargement. Following this report, on 26 January 2000, the Commission presented its opinion entitled "Adapting the institutions to make a success of enlargement".

After consultation of the Commission and Parliament, whose opinions must be sought before an IGC is convened (Article 48 of the EU Treaty), the conference of Member States' government representatives opened on 14 February 2000 under the Portuguese Presidency. From July 2000 the IGC worked under the French Presidency.


The Intergovernmental Conference which resulted in the Treaty of Nice had the very clear mandate of preparing the European Union for enlargement by revising the Treaties in four key areas:

  • size and composition of the Commission;
  • weighting of votes in the Council;
  • extension of qualified-majority voting;
  • enhanced cooperation.


The Treaty of Nice consists of two parts and four Protocols. In addition, the IGC adopted 24 Declarations and took note of three more from different Member States which were also annexed to the Final Act.

The first part includes the most substantive amendments in the following six Articles:

  • Article 1 deals with the amendments made to the EU Treaty:- serious breach of EU founding principles;- common foreign and security policy (CSFP);- international agreements;- enhanced cooperation;- judicial cooperation in criminal matters.
  • Article 2 deals with the amendments made to the Treaty establishing the European Community:- extension of the qualified majority;- establishment of a Social Protection Committee;- the status of Members of Parliament and European Political Parties;- the Commission (composition and role of the President);- the other institutions (Court of Justice, Court of Auditors, European Economic and Social Committee, Committee of the Regions);- the European Investment Bank;- title of the Official Journal.
  • Article 3 deals with the amendments made to the Treaty establishing the European Atomic Energy Community (Euratom Treaty).
  • Article 4 deals with the amendments made to the treaty establishing the European Steel and Coal Community (ECSC Treaty).
  • Article 5 deals with the amendments made to the Protocol on the Statute of the European System of Central Banks and of the European Central Bank.
  • Article 6 deals with the amendments made to the Protocol on the privileges and immunities of the European Communities

Part two, which consists of Articles 7 to 13, includes the transitional and final amendments.

Lastly four Protocols are annexed to the Treaties:

  • the Protocol on the enlargement of the European Union dealing with the composition of the European Parliament and the Commission and the weighting of votes in the Council;
  • the Protocol on the Statute of the Court of Justice and the Court of First Instance;
  • the Protocol on the financial consequences of the expiry of the ECSC Treaty (European Coal and Steel Community);
  • the Protocol on Article 67 of the EU Treaty (administrative cooperation between the Member States' administrations over "visas, asylum, immigration and other policies related to free movement of persons").


The institutional reform achieved in Nice has been described as "technical" and "limited". The Treaty does not, in fact, drastically change the institutional balance but rather makes some adjustments, mainly to the function and composition of the institutions and enhanced cooperation. In addition to the discussion on the reform of the institutions, some more unusual non-institutional topics were tackled.

In the interests of clarity this guide to the Treaty of Nice has been divided into three chapters covering the main changes that have been made.

Institutional questions

  • The Council of the European Union and the new weighting of votes in the Council: adjustment in the weighting of votes in favour of the more populated Member States and redistribution of votes among the 25 then 27 Member States.
  • The European Commission: change in the composition of the Commission, increase in the powers of the President and change in the way he or she is nominated.
  • Judicial System: new division of tasks between the Court of Justice and the Court of First Instance and the possible creation of specialist judicial Chambers.
  • Other Institutions:Parliament: extension of the codecision procedure and adjustment of the number of seats allocated to each current and future Member State. The Court of Auditors, the European Economic and Social Committee and the Committee of the Regions: composition and nomination of members.

The decision-making process

Enhanced Cooperation: the Treaty of Nice has made the enhanced cooperation system more flexible (less strict conditions, removal of the right to veto, more fields of application).

Qualified-majority voting: extension of the qualified-majority decision-making process to around thirty new Articles.

Other reforms

These involve several thematic provisions relating to fundamental rights, security and defence policy, cooperation over criminal law, the status of European political parties as well as a number of provisions contained in the Declarations and Protocols annexed to the Treaty.


Declaration on the future of the Union

In a Declaration on the future of the Union annexed to the Treaty of Nice, the intergovernmental conference called for a deeper and wider debate on the future of the European Union. The debate was to involve national parliaments and all public opinion as well as the candidate countries and lead to the convening of a new IGC in 2004.

The debate was to address four key issues in particular:

  • a more precise demarcation of responsibilities between the European Union and the Member States;
  • the status of the Charter of Fundamental Rights of the European Union;
  • a simplification of the Treaties;
  • the role of national parliaments in the European architecture.

The Laeken Declaration (December 2001)

At its meeting in Laeken in December 2001 the European Council presented the agreed method for bringing about reform (a Convention) and the timetable, and defined the agenda for the debate.

The Convention

In accordance with the Laeken Declaration a Convention was organised in order to prepare for the next IGC which, like the Convention that established the Charter of fundamental rights, involved representatives from national governments and parliaments in the Member States and candidate countries and representatives from the European Parliament and the Commission. Its inaugural session was held on 28 February 2002 and work came to an end after 17 months of discussions.

The Convention drew up a draft Treaty establishing a European Constitution which was presented by its President, Mr Giscard d'Estaing, to the Thessaloniki European Council. The Convention concluded is work in July 2003.

The Intergovernmental Conference and the draft Constitution

The draft Constitution, the result of the Convention's work, served as a basis for the negotiations at the IGC convened in October 2003. After a political agreement was reached on 18 June 2004, building on the work of the IGC, the draft Constitution was forwarded to the Heads of State and Government, all of whom signed it on 29 October 2004.

The ratification of the Constitution was the final stage prior to its entry into force. It had to be ratified by all the Member States in accordance with each one's constitutional rules, namely either parliamentary ratification or referendum.

Following the difficulties in ratifying the Treaty in some Member States, the Heads of State and Government decided, at the European Council meeting on 16 and 17 June 2005, to launch a "period of reflection" on the future of Europe.

The Treaty of Lisbon

At the European Council meeting on 21 and 22 June 2007, European leaders reached a compromise and agreed to convene an IGC to finalise and adopt, not a Constitution, but a reform treaty for the European Union. The final text of the treaty, drawn up by the IGC, was approved at the informal European Council in Lisbon on 18 and 19 October. The Treaty of Lisbon was signed by the Member States on 13 December 2007.

The Treaty of Nice modified by the accession treaties

When the Treaty of Nice was being drawn up, it was not known when and in what order the candidate countries would join the Union. The Treaty of Nice was therefore confined to setting out the principles and methods for changing the composition of the Commission and redefining the qualified majority in the Council. Thus, as anticipated in the Protocol on enlargement and the Declarations annexed to the Treaty, the allocation of Parliamentary seats and Council votes to the new Member States and the qualified majority threshold applicable in the future were determined legally in their accession treaties. The Treaty of Accession of the ten new Member States, signed in Athens on 16 April 2003, and the Treaty of Luxembourg on the accession of Romania and Bulgaria, signed on 25 April 2005, thus lay down the rules in this area. Since 1 January 2007 the foundation of the Union has therefore been the EU and EC Treaties as last amended by the Treaties of Nice, Athens and Luxembourg.

Last updated: 11.01.2008