The International Committee for Weights and Measures (abbreviated CIPM from the French Comité international des poids et mesures) consists of eighteen persons from Member States of the Metre Convention (Convention du Mètre) appointed by the General Conference on Weights and Measures (CGPM) whose principal task is to ensure worldwide uniformity in units of measurement by taking direct action or by submitting proposals to the CGPM.
A recent focus area of the CIPM has been the establishment of the CIPM Arrangement de reconnaissance mutuelle (Mutual Recognition Arrangement, MRA) which serves as the framework for the mutual acceptance of measurements performed in the Member States of the Metre Convention.
The CIPM meets annually at the International Bureau of Weights and Measures (BIPM, Bureau international des poids et mesures), and discusses reports presented to it by its Consultative Committees. It issues an Annual Report on the administrative and financial position of the BIPM to the governments of the Member States of the Metre Convention.
The CIPM has set up a number of consultative committees (CC) to assist it in its work. These committees are under the authority of the CIPM. The president of each committee, who is expected to take the chair at CC meetings, is usually a member of the CIPM. Apart from the CCU, members of the CCs are appointed by the CIPM from metrologists with appropriate experience based in the various member states.
These committees are:
The CCRI has three separate sub-committees, each looking at different parts of the electromagnetic spectrum.
The CCU's role is to advise on matters related to the development of the SI and the preparation of the SI brochure. Unlike other CC's, its membership is made up of nominees from other prominent national and international bodies such as International Organization for Standardization (ISO), National Institute of Standards and Technology (NIST), National Physical Laboratory (NPL), International Astronomical Union (IAU), International Union of Pure and Applied Chemistry (IUPAC) and International Union of Pure and Applied Physics (IUPAP).[Note 1]
From time to time the CIPM has been charged by the CGPM to undertake major investigations related to activities affecting the CGPM or the BIPM. Reports produced include:
The Blevin Report, published in 1998, examined the state of worldwide metrology. The report originated from a resolution passed at the 20th CGPM (October 1995) which committed the CIPM to
to study and report on the long-term national and international needs relating to metrology, the appropriate international collaborations and the unique role of the BIPM to meet these needs, and the financial and other commitments that will be required from the Member States in the coming decades.
The report identified, amongst other things, a need for closer cooperation between the BIPM and other organisations such as International Organization of Legal Metrology (OIML) and International Laboratory Accreditation Cooperation (ILAC) with clearly defined boundaries and interfaces between the organisations. Another major finding was the need for cooperation between accreditation laboratories and the need to involve developing countries in the world of metrology.
The Kaarls Report published in 2003 examined the role of the BIPM in the evolving needs for metrology in trade, industry and society.
The CIPM has responsibility for commissioning the SI brochure, which is the formal definition of the International system of units. The brochure is produced by the CCU in conjunction with a number of other international organisations. Initially the brochure was only in French – the official language of the metre convention, but recent versions have been published simultaneously in both English and French, with the French text being the official text. The 6th edition was published in 1991, the 7th edition was published in 1998, and the 8th in 2006.