International Legal Metrology Documentary Standards

The International Organization of Legal Metrology (OIML)

OIML is the international organization for developing documentary standards related to regulated and legally mandated measurements. OIML is an inter-governmental treaty organization established in 1955 by the “Convention” (the treaty), which has an objective of harmonization of national regulations and metrological controls (e.g., type approval, verification, etc.) applied by legal metrology authorities. There are 60 Member States (voting) and 68 Corresponding Members (nonvoting). The oversight body of OIML is the International Committee of Legal Metrology (CIML), which meets annually. Each Member State has one CIML Member. A meeting of the OIML Conference is held every four years to establish general policy, vote on the budget and confirm the decisions of the CIML. The United States ratified the Convention and joined OIML in 1972.

The OIML utilizes Technical Committees (TCs), Subcommittees (SCs), and Project Groups (PGs) comprised of representatives from member countries to develop model regulations and standards. In OIML, the standards are referred to as Recommendations. International consensus in the legal metrology community is reached through TC, SC and PG activities. The composition of the TCs SCs and PGs includes representatives from Member States and liaison representation from international standardization and technical organizations, manufacturers’ associations and regional regulatory bodies. Under the coordination of a Secretariat or a Convener, experts establish international technical guidelines for the metrological performance and testing procedures of measuring instruments subject to legal controls. The TCs are organized by general measurement discipline and the SCs are assigned specific types of measuring instruments or areas for standards development. The PGs focus on individual projects and are disbanded after completing their mission.

During development, Recommendations go through successive incomplete drafts designated as 1 WD (Working Draft), 2 WD, etc. When a TC, SC or PG addresses all necessary elements in a Recommendation the designation shifts from a WD to a Committee Draft (CD) with successive drafts numbered 1CD, 2 CD, etc. Following a successful TC, SC or PG ballot and approval, a CD is designated as a Draft Document (DD) or a Draft Recommendation (DR) and sent to the International Bureau of Legal Metrology (BIML) for approval by the CIML. The BIML provides the administrative, technical and editorial staffing function for the OIML. Following CIML approval, the BIML publishes and provides for free distribution of the Documents and Recommendations through the OIML website.

The OIML has developed a Certificate System for measuring instruments that comply with the Recommendations to promote global regulatory-body acceptance of test reports, thereby avoiding duplicative type evaluation testing requirements. Manufacturers may submit instruments to testing facilities authorized by national Issuing Authorities, which are designated by their CIML Members. The OIML web site database lists the Issuing Authorities and the OIML Certificates of Conformity (CC) submitted by the various national Issuing Authorities for registration by the BIML.