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JUNE 2008 

International Legal Metrology Organizational Primer 

By S. Wayne Stiefel 

1. Measurement 

 

1.1 The International Bureau of Weights and Measures 

The International Bureau of Weights and Measures, formally known by its French name, Bureau International des 

Poids et Measures (BIPM) in Paris, is responsible for the definition of the International System of Units (SI) and 

promoting worldwide consistency of physical measurements. It is the institute that coordinates many international 

metrology activities, and performs metrology research. The BIPM operates under the supervision of the 

International Committee for Weights and Measures (CIPM). The CIPM suggests modifications to the SI to the 

General Conference on Weights and Measures (CGPM) for formal adoption. The CGPM is the primary 

intergovernmental treaty organization1 responsible for the SI, representing nearly 50 countries. Both the BIPM and 

the CIPM were established by the Meter Convention, which was signed in Paris in 1875 by representatives of 

seventeen nations, including the United States. Refinement of the SI is an ongoing process aided by the work of 

BIPM’s Consultative Committees: Electricity and Magnetism, Photometry and Radiometry, Thermometry, Length, 

Time and Frequency, Units, Mass and related quantities, and Amount of substance. 

1.2 National Metrology Institutes 

 

Within countries, measurements are made consistent/comparable through traceability to their primary standards 

maintained by the National Metrology Institutes (NMIs); the United States’ NMI is the National Institute of 

Standards and Technology (NIST). Each NMI is responsible for maintaining the primary standards, usually 

recognized by national law, that serve in its country as the basis for assigning values to other standards of the 

quantity concerned. 

1.3 Regional Metrology Organizations (RMOs) 

NIST is the U.S. member of the Inter-American Metrology System (SIM). All RMOs have as their objectives: 

• Information exchange on measurement standards and capabilities 

• Provision of international credibility for measurement traceability and competence as a basis for a global 

Mutual Recognition Arrangement (MRA) for metrology standards and calibration certificates issued by 

National Metrology Institutes 

• Training of personnel to upgrade measurement capability within the region 

• Facilitation of traceability of measurement through calibration and comparison of national standards, and 

• Collaboration with BIPM, including the key comparison database, and also with other counterpart regional 

bodies. 

Other RMOs with similar objectives include the: 

• Asia Pacific Metrology Program (APMP) 

• Euro-Asian Cooperation of National Metrological Institutions (COOMET) 

• European Association of National Metrology Institutes (EURAMET), and the 

• Southern African Community Cooperation in Measurement Traceability (SADCMET). 

1.4 Accreditation 

Accreditation of calibration and testing laboratories serves the objectives of the government and the private sector 

(industry, consumers, and other stakeholders) by fostering and promoting a uniformly acceptable base of 

professional and technical competence in the laboratory community, and facilitating and promoting acceptance of 
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calibration and test results among countries to avoid barriers to trade. Testing and calibration laboratory 

accreditations underpin an infrastructure of competent measurement laboratories supporting domestic and 

international trade and conformity assessment activities. Accreditation programs provide an unbiased third-party 

evaluation and recognition of capability and performance, as well as expert technical guidance to upgrade laboratory 

performance. 

1.4.1 International Accreditation Organizations 

The International Laboratory Accreditation Cooperation (ILAC) has the aim of developing international cooperation 

for facilitating trade by promotion of the acceptance of accredited test and calibration results. ILAC membership is 

open to laboratory accreditation organizations that have been accepted as signatories to the ILAC Mutual 

Recognition Arrangement. Each accreditation body that is a signatory to the Arrangement agrees to abide by its 

terms and conditions and by the ILAC evaluation procedures. To do this, the signatory must: 

• Maintain conformance with ISO/IEC 17011 Conformity assessment: General requirements for 

accreditation bodies accrediting conformity assessment bodies, related ILAC guidance documents, and a 

few, but important, supplementary requirements; 

• Ensure that all its accredited laboratories comply with ISO/IEC 17025 General requirements for the 

competence of testing and calibration laboratories and related ILAC guidance documents. 

These signatories have, in turn, been peer-reviewed and shown to meet ILAC’s criteria for competence. 

The International Accreditation Forum, Inc. (IAF) is the world association of Conformity Assessment Accreditation 

Bodies and other bodies interested in conformity assessment in the fields of management systems, products, 

services, personnel and other similar programs of conformity assessment. The purpose of the IAF is to ensure that its 

accreditation body members accredit only competent bodies and to establish mutual recognition arrangements, 

known as Multilateral Recognition Arrangements (MLA), among its members. Accreditation body membership in 

IAF is open to organizations that accredit bodies for certification/registration of management systems, products, 

services, personnel or similar programs of conformity assessment. 

1.4.2 Regional Laboratory Accreditation Organizations (RLAO’s) 

RLAO’s that cooperate with members in their region and with ILAC and/or IAF to foster accreditation activities 

include: 

• Asia Pacific Laboratory Accreditation Cooperation (APLAC) 

• Central Asian Cooperation on Metrology Accreditation and Quality (CAC-MAS-Q) 

• European Cooperation for Accreditation (EA) 

• Inter-American Accreditation Cooperation (IAAC) 

• Pacific Accreditation Cooperation (PAC), and 

• Southern African Development Community in Accreditation (SADCA). 

RLAO activities that support mutual recognition and acceptance of accredited services and results include: meetings 

for exchange of information and to promote discussion, such as common interpretation of standards; management of 

peer evaluations; organization of proficiency testing; development and promotion of mutual recognition 

arrangements among Members, and cooperation with other national, regional and international bodies with 

similar or complementary objectives. Accreditors domiciled in the United States seeking mutual recognition work 

through the APLAC. 

2. Documentary Standards 

2.1 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 
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(e.g., type approval, verification, etc) applied by legal metrology authorities. There are 59 Member States (voting) 

and 56 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) and Subcommittees (SCs) comprised of representatives from 

member countries to develop model regulations and standards. The standards are referred to in OIML as 

Recommendations. International consensus in the legal metrology community is reached through TC and SC 

activities. The composition of the TCs and SCs 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, 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. During development, Recommendations go through 

successive incomplete drafts designated as 1 WD (Working Draft), 2 WD, etc. When a TC or SC 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 or SC 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. 

 

The OIML has developed a Mutual Acceptance Arrangement (MAA) that is related to the OIML Certification 

system used for Type Evaluations. The goal of the MAA is for the participants to accept and utilize Test Reports 

validated by an OIML MAA Certificate of Conformity. The scheme designates Participants in the MAA as either 

Issuing Participants (IPs) or Utilizing Participants (UPs). Issuing Authorities that will issue and use OIML MAA 

Certificates of Conformity are designated as IPs. Tests reports associated with these OIML MAA Certificates will 

also be accepted and utilized by UPs to issue, for example, national type approvals. To foster confidence, the MAA 

includes an evaluation of the competence and testing capabilities of the Testing Laboratories of OIML Issuing 

Authorities applying to be an IP, according to the international standard ISO/IEC 17025 General requirements for 

the competence of testing and calibration laboratories. This evaluation may be carried out either by accreditation or 

by peer assessment. The Committee on Participation Review (CPR), comprised of experts from participating 

countries, studies the application files of potential participants and decides on the need to conduct peer assessments, 

considering the accreditation of the Testing Laboratories and the scope of these accreditations. Evaluation reports 

are distributed to the participants, and when all participants agree on the acceptability of the IP applicants, the IP 

applicants are allowed to sign the Declaration of Mutual Confidence (DoMC). The initial MAA implementation 

covers OIML R 60 (Load cells) and OIML R 76 (Nonautomatic weighing instruments), for which a large number of 

OIML Certificates have been issued. The first two Declarations of Mutual Confidence were published by the BIML 

in September 2006. The National Conference on Weights and Measures (NCWM) signed the DoMC (as a Utilizing 

Participant) for R60. Consequently, the U.S. National Type Evaluation Program (NTEP) will accept test data on 

load cells that are tested according to the requirements in OIML R60 (and additional, agreed-upon requirements), 

from Issuing Participants under the DoMC, to use as the basis of issuing NTEP Certificates. A DoMC for OIML 

R49 (Water meters) was begun in 2007. 

2.2 Other International Standards Organizations 

To avoid conflicting requirements for measuring instruments, the OIML establishes liaisons with international and 

regional institutions concerning activities in metrology, standardization and related fields including: the International 
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Bureau of Weights and Measures (BIPM), the International Organization for Standardization (ISO), the International 

Electrotechnical Commission (IEC), the International Federation of Clinical Chemistry (IFCC), and the International 

Union of Pure and Applied Physics (IUPAP). The complete list is on the OIML liaison website. These organizations 

develop standards for related aspects of measuring instruments, such as safety; interoperability, and performance 

requirements not necessarily directly related to legal metrology. 

2.3 Regional Legal Metrology Organizations (RLMOs) 

The RLMOs provide a forum for sharing information on legal metrology in member countries and economies to 

promote a harmonized and consistent approach to legal metrology requirements in the region. RLMOs also facilitate 

communications and shared training opportunities. Shared specific objectives include supporting an integrated 

measurement infrastructure in the region, promoting equity in the market place, improving the quality of life and 

facilitating international trade. 

 

For the United States, NIST is a member of both the Inter-American Metrology System - Legal Metrology Working 

Group (SIM -LMWG), and the Asia-Pacific Legal Metrology Forum (APLMF). 

Other regional legal metrology organizations with similar roles include the: 

• Euro-Asian Cooperation of National Metrological Institutions (COOMET) 

• Euro-Mediterranean Legal Metrology Forum (EMLMF), and 

• European Cooperation in Legal Metrology (WELMEC) 

3. Laws and Regulations 

National, state and local governments determine through the legislative process how to ensure that equity in the 

marketplace, and the safety and health of the public are maintained. Measurements play a crucial role and are tied to 

laws and regulations that govern the accuracy of measuring instruments and their conformity to national or 

recognized international specifications. Legal metrology involves not only the facilitation of traceability, but also 

means for detecting fraud (tampering), accidental misuse, and inaccuracy caused by influence factors which disrupt 

the measurement process. Instruments are controlled through a system of type approval, initial verification and 

marketplace surveillance. 

4. Economic Promotion Organizations 

Several global and regional organizations are focused on promoting international trade and fostering development 

necessary for free trade. An essential element for trade recognized by these organizations is legal metrology. The 

following organizations have supported developing such infrastructure in developing countries around the world. 

The World Trade Organization (WTO) deals with the rules of trade among nations at a global or near-global level. 

It’s an organization for liberalizing trade. It’s a forum for governments to negotiate global trade agreements. It’s a 

place for them to settle trade disputes. It operates on a system of rules covering global trade and associated aspects. 

The Organization of American States (OAS) has dual roles in promoting development. On a political level, it fosters 

dialogue and consensus on ways to combat poverty and improve the level of development in the region. The OAS 

also mobilizes funds so member states can carry out projects in priority areas. 

The United Nations Industrial Development Organization’s (UNIDO) objective is to reduce poverty in countries 

with developing and transition economies through: sustainable industrial growth with emphasis on productive 

economic activities; trade capacity building; and promotion of energy efficiency, renewable energy and 

environmental sustainability. 

The World Bank is a vital source of financial and technical assistance to developing countries around the world to 

support its mission of reducing global poverty and improving living standards. The World Bank is made up of two 

unique development institutions owned by 185 member countries: the International Bank for Reconstruction and 

Development focuses on middle income and creditworthy poor countries, while the International Development 
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Association focuses on the poorest countries in the world. Together they provide low-interest loans, interest-free 

credit and grants to developing countries for education, health, infrastructure, communications and many other 

purposes. 

The United States Agency for International Development (USAID) is an independent U.S. federal government 

agency that receives overall foreign policy guidance from the Secretary of State. USAID supports long-term 

economic growth, agriculture and trade in countries recovering from disaster, trying to escape poverty and engaging 

in democratic reforms. 

GLOSSARY OF ACRONYNMS 

(Acronyms in Red are cross-linked to web sites) 

APLAC Asia Pacific Laboratory Accreditation Cooperation 

APLMF Asia-Pacific Legal Metrology Forum 

APMP Asia Pacific Metrology Program 

BIML International Bureau of Legal Metrology 

BIPM International Bureau of Weights and Measures 

CAC-MAS-Q Central Asian Cooperation on Metrology Accreditation and Quality 

CC Certificate of Conformity 

CD Committee Draft 

CGPM General Conference on Weights and Measures 

CIPM International Committee for Weights and Measures 

COOMET Euro-Asian Cooperation of National Metrological Institutions 

CPR Committee on Participation Review 

DD Draft Document 

DoMC Declaration of Mutual Confidence 

DR Draft Recommendation 

EA European Cooperation for Accreditation 

EMLMF Euro-Mediterranean Legal Metrology Forum 

EUROMET European Collaboration in Measurement Standards 

IAAC Inter-American Accreditation Cooperation 

IAF International Accreditation Forum 

IEC International Electrotechnical Commission 

IFCC International Federation of Clinical Chemistry 

ILAC International Laboratory Accreditation Cooperation 

ISO International Organization for Standardization 

IUPAP International Union of Pure and Applied Physics 

MAA Mutual Acceptance Arrangement 

MLA Multilateral Recognition Arrangements 

MRA Mutual Recognition Arrangement 

NCWM National Conference on Weights and Measures 

NIST National Institute of Standards and Technology 

NMIs National Metrology Institutes 

NTEP National Type Evaluation Program 

OAS Organization of American States 

OIML International Organization of Legal Metrology 

PAC Pacific Accreditation Cooperation 

R Recommendation 
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RLAOs Regional Laboratory Accreditation Organizations 

RLMOs Regional Legal Metrology Organizations 

RMOs Regional Metrology Organizations 

SADCA Southern African Development Community in Accreditation 

SADCMEL Southern African Community Cooperation in Measurement Traceability 

SC Technical Subcommittee 

SI International System of Units 

SIM Inter-American Metrology System 

SIM-LMWG Inter-American Metrology System - Legal Metrology Working Group 

TC Technical Committee 

UNIDO United Nations Industrial Development Organization 

USAID United States Agency for International Development 

WD Working Draft 

WELMEC European Cooperation in Legal Metrology 

WTO World Trade Organization