Composition before 1967
On 9 May 1950, the French Foreign Affairs Minister, Robert Schuman, proposed the creation of the High Authority, the executive body of the European Coal and Steel Community (ECSC). During the negotiations preceding its creation, the Member States agreed to a limited number of members in order to ensure the cohesion and the efficiency of the institution. It was ultimately decided that the Commission be composed of nine members, with Germany, France and Italy having two members each and the Benelux countries one member each (Article 9 of the ECSC Treaty).
The composition of the two new executive bodies provided for in the Treaties of Rome of 25 March 1957 fulfilled the same requirements:
— the Commission of the European Economic Community (EEC) was composed of nine members (Article 157 of the EEC Treaty);
— the Commission of the European Atomic Energy Community (EAEC or Euratom) was composed of five members (Article 126 of the Euratom Treaty).
Composition after 1967
On 1 July 1967, these three institutions were replaced by a Single Commission under the Merger Treaty. The composition of this new Commission was a divisive issue, as governments sought to defend their respective interests. They eventually reached agreement on a transitional solution whereby, until the entry into force of the Treaty establishing a Single European Community, or until three years after the appointment of its members, whichever was the earlier, the Commission would consist of 14 members (Article 32 of the Merger Treaty). Among these members were several who had already served in the Commission of the European Economic Community. The Commission would have 14 members until 1 July 1970. At the end of that term of office, its composition would be determined by Article 10 of the Merger Treaty which specified nine Commission members.
The number of members of the Commission has been amended by the Council as a result of the accession of new Member States. Accordingly, the number of members has gradually increased:
— 14 members (6 July 1967)
— 9 members (1 July 1970)
— 13 members (6 January 1973)
— 14 members (6 January 1981)
— 17 members (1 January 1986)
— 20 members (23 January 1995)
— 30 members (1 May 2004)
— 25 members (1 November 2004)
— 27 members (1 January 2007).
Only nationals of the Member States may be members of the Commission, which must comprise at least one national from each Member State, but not more than two members holding the nationality of the same State. In practice, the distribution of seats among Member States does not follow a written rule; however, France, Germany, Italy, Spain and the United Kingdom have two members, whereas other Member States have only one.
The composition of the Commission nevertheless remains a widely debated issue, since many people are of the opinion that there are too many members. The Treaty of Amsterdam of 2 October 1997 included a Protocol on the institutions with the prospect of enlargement of the European Union. It set out institutional conditions to be fulfilled by the date of entry into force of the first enlargement of the Union: to reduce the number of Commissioners to one national per Member State, provided that the weighting of votes within the Council is amended in such a way that is acceptable to all Member States.
Each of the 10 States that acceded to the European Union on 1 May 2004 had a Commissioner for the period between their accession date and 31 October 2004. From 1 November 2004, the Commission is composed of one member per Member State. The Treaty of Nice of 26 February 2001 introduced a Protocol on the enlargement of the European Union which provides that, when the Union consists of 27 Member States, the Commissioners shall be less than the number of Member States and shall be chosen in accordance with a rotation system based on the principle of equality. This amendment will apply to the first Commission which takes up its duties following the accession of the 27th Member State.