International Organization of Legal Metrology

French language International Organization for Standardization International Bureau of Weights and Measures
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International Organization of Legal Metrology
OIML blue logo.jpg
Formation1955; 65 years ago (1955)
Legal statusTreaty
PurposeLegal metrology
HeadquartersParis, France
Region served
Sovereign states
Official language
English, French
€2 million

The International Organization of Legal Metrology (French: Organisation Internationale de Métrologie Légale - OIML), is an intergovernmental organization that was created in 1955 to promote the global harmonization of the legal metrology procedures that underpin and facilitate international trade.

Such harmonization ensures that certification of measuring devices in one country is compatible with certification in another, thereby facilitating trade in the measuring devices and in products that rely on the measuring devices. Such products include weighing devices, taxi meters, speedometers, agricultural measuring devices such as cereal moisture meters, health related devices such as exhaust measurements and alcohol content of drinks.

Since its establishment, the OIML has developed a number of guidelines to assist members, particularly developing nations, to draw up appropriate legislation concerning metrology across all facets of society and guidelines on certification and calibration requirements of new products, particularly where such calibration has a legal impact such as in trade, health care and taxation.

The OIML works closely with other international organizations such as the International Bureau of Weights and Measures (BIPM) and International Organization for Standardization (ISO) to ensure compatibility between each organization's work. The organization has no legal authority to impose solutions on its members, but its Recommendations are often used by Member States as part of their own domestic law.

As of June 2020, 61 countries had signed up as Member States and a further 62 as Corresponding (non-voting) Members including all the G20, EU and BRICS countries. Between them, the OIML Members cover 86 % of the world's population and 96 % of its economy.

The Headquarters of the OIML is located in Paris, France.

Definition of "legal metrology"

The definition of "legal metrology" varies amongst jurisdictions, reflecting the extent to which metrology is bound into the jurisdiction's own legal and regulatory code. The OIML, in their publication International Vocabulary of Terms in Legal Metrology defined "legal metrology" as[1]

... concerns regulatory requirements of measurements and measuring instruments for the protection of health, public safety, the environment, enabling taxation, protection of consumers and fair trade.

In the glossary of their book Metrology - in short Howarth and Redgrave state that "legal metrology"[2]

Ensures accuracy and reliability of measurement where measured values can affect health, safety, or the transparency of financial transactions e.g. weights and measures.

These two statements are held together by the words "regulatory", "accuracy" and "reliability". The word "regulatory" encompasses the "legal" aspects of the term – the role played by governments, national metrology institutes and standards organizations in creating a framework to ensure confidence in the accuracy and reliability of a measurement. This framework requires that the specified test and conformance operations are carried out, and that the certificates pertaining to these operations are filed in a manner that enables third parties to assess them should the need arise.

The OIML has identified four main activities that fulfil the purposes of legal metrology:[3]


The International Organization of Legal Metrology (OIML), an intergovernmental organization, was established under a diplomatic treaty signed in Paris on 12 October 1955 to promote the global harmonization of legal metrology procedures that underpin and facilitate international trade.[4] Under French law, its principal body, the International Conference is accorded diplomatic status.[5]

The Convention that set up the OIML listed eight objectives behind its establishment. At the 2011 meeting in Prague of the International Committee of Legal Metrology (CIML), the OIML updated its mission to read:[6]

The mission of the OIML is to enable economies to put in place effective legal metrology infrastructures that are mutually compatible and internationally recognized, for all areas for which governments take responsibility, such as those which facilitate trade, establish mutual confidence and harmonize the level of consumer protection worldwide.

At the same meeting, its objectives were then stated as follows:[6]

  1. "To develop, in cooperation with our stakeholders, standards and related documents for use by legal metrology authorities and industry that when implemented will achieve the mission of the OIML".
  2. "To provide mutual recognition systems which reduce trade barriers and costs in a global market".
  3. "To represent the interests of the legal metrology community within international organizations and forums concerned with metrology, standardization, testing, certification and accreditation".
  4. "To promote and facilitate the exchange of knowledge and competencies within the legal metrology community worldwide".
  5. "In co-operation with other metrology bodies, to raise awareness of the contribution that a sound legal metrology infrastructure can make to a modern economy".
  6. "To identify areas for the OIML to improve the effectiveness and efficiency of its work".


The OIML, which has an annual operating budget of about two million euros that comes from member subscriptions[7][Note 1] is organized around a three-layer model:[4][8][9]

The overall direction of the OIML is vested in the International Conference (French: Conférence internationale de Métrologie légale) which meets every four years. The Conference is attended by delegations from Member States and [non-voting] Corresponding Members of the Organization.

The management of the OIML is vested in the International Committee (French: Comité international de Métrologie légale - CIML). The Committee consists of one member from each Member State. These members normally have active official functions in legal metrology in their country. The Committee elects a non-salaried President for a six-year term of office from amongst its members. The Committee meets annually under the chairmanship of its President.

Secretarial services, day-to-day running and financial management of the OIML are provided by the BIML (French: Bureau International de Métrologie légale). The BIML is the OIML headquarters, located in the 9th Arrondissement of Paris[10] and is headed by a salaried director who is, ex-officio, secretary to both the International Conference and the International Committee.

Senior postholders

Participation and membership

The OIML has two categories of membership; "Member State" and "Corresponding Member". The Member State category is for countries or economies that are prepared to finance and actively participate in the work of the OIML and which have acceded to the OIML Convention.

The Corresponding Member category is for countries or economies that want to be informed of OIML activities, but cannot, or prefer not to, be a Member State.[13] As of June 2020 a total of 61 states are Member States and 62 are Corresponding Members.[14]

Member States

Corresponding Members


Technical Committees

The technical work of the OIML is carried out by Technical Committees (TC), each committee having responsibility for a different aspect of legal metrology. In some cases the Technical Committee is broken up into one or more Subcommittees (SC). Within each TC or SC the actual technical work is carried out by Project Groups led by conveners. TCs, SCs and Project Groups are led by volunteer experts from OIML Member States. As of June 2020 there are 18 Technical Committees and 46 Subcommittees. The Technical Committees are:[15]


The OIML produces a number of publications, including:

Vocabularies (prefixed by the letter "V") that provide standardized terminology in the field of metrology. The OIML has produced two principal works:

In addition, the OIML was a partner in the JCGM[Note 2] which produced the International vocabulary of metrology - Basic and general concepts and associated terms (VIM), a document published by the BIPM on behalf of the JCGM

Recommendations (prefixed by the letter "R") which are model regulations that establish the metrological characteristics required of certain measuring instruments and which specify methods and equipment for checking their conformity. Most of the Recommendations have a similar structure. The four main topics covered in the reports are metrological requirements, technical requirements, methods and equipment for testing and verifying conformity to requirements and test report format.[2] Recommendations are written in such a manner that they can be adopted "as is" by countries that wish to do so, or countries can select those parts that they wish to include in their own legislation. As of June 2020 104 Recommendations have been published, usually in both English and French.[16] Recommendations may be downloaded free of charge from the OIML website.

International Documents (prefixed by the letter "D"), which are informative in nature and intended to improve the work of the metrological services. As of June 2020 29 OIML Documents had been published in this series. Documents may be downloaded free of charge from the OIML website.

The OIML also published Basic Publications, Guides, Seminar Reports, Expert Reports and the OIML Bulletin.

OIML Certification System (OIML-CS)

The OIML-CS is a system for issuing, registering and using OIML Certificates and their associated OIML type evaluation/test reports for types of measuring instruments (including families of measuring instruments, modules, or families of modules), based on the requirements of OIML Recommendations. It is a single Certification System comprising two Schemes: Scheme A and Scheme B. It was launched on 1 January 2018, replacing the OIML Basic Certificate System and the OIML Mutual Acceptance Arrangement (MAA).

The aim of the OIML-CS is to facilitate, accelerate and harmonize the work of national and regional bodies that are responsible for type evaluation and approval of measuring instruments subject to legal metrological control.

The objectives of the OIML-CS are

a) to promote the global harmonization, uniform interpretation and implementation of legal metrological requirements for measuring instruments and/or modules,

b) to avoid unnecessary re-testing when obtaining national type evaluations and approvals, and to support the recognition of measuring instruments and/or modules under legal metrological control, while achieving and maintaining confidence in the results in support of facilitating the global trade of individual instruments, and

c) to establish rules and procedures for fostering mutual confidence among participating OIML Member States and Corresponding Members in the results of type evaluations that indicate conformity of measuring instruments and/or modules, under legal metrological control, to the metrological and technical requirements established in the applicable OIML Recommendation(s).

There are three categories of participants:

The requirements for the participation of OIML Issuing Authorities and their associated Test Laboratories in Scheme A or Scheme B are the same, but the method of demonstrating compliance is different. OIML Issuing Authorities are required to demonstrate compliance with ISO/IEC 17065 and Test Laboratories are required to demonstrate compliance with ISO/IEC 17025. For participation in Scheme B, it is sufficient to demonstrate compliance on the basis of “self-declaration” with additional supporting evidence. However, for participation in Scheme A, compliance shall be demonstrated by peer evaluation on the basis of accreditation or peer assessment.


The work of the OIML overlaps with the work of a number of other international organisations. In order to minimise the impact of this overlap and also to ensure that the work of the OIML and other organisations can intermesh with each other, the OIML and other organisations have exchanged memoranda of understanding (MoU) with each other. As of July 2019 the MoU in existence were:[17]

See also


  1. ^ Subscriptions currently range from €1 400 for Corresponding Members to €112 000 for Member States that have a population of over 100 million.
  2. ^ The Joint Committee for Guides in Metrology (JCGM) has eight members: BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, ILAC and the OIML.
  3. ^ This has financial implications as the OIML is funded mainly by member subscriptions and ISO by the sale of standards.


  1. ^ International Vocabulary of Terms in Legal Metrology (PDF). Paris: OIML. 2000. p. 7. Archived from the original (PDF) on 2013-05-28.
  2. ^ a b Howarth, Preben; Redgrave, Fiona (July 2008). Metrology - in short (3rd ed.). Danish Fundamental Metrology & National Physical Laboratory. pp. 35–36. ISBN 978-87-988154-5-7.
  3. ^ "Legal Metrology". OIML. Retrieved 3 February 2013.
  4. ^ a b "Convention establishing an International Organization of Legal Metrology" (PDF). International Organization of Legal Metrology. 12 October 1955. Archived from the original (PDF) on 3 July 2009. Retrieved 4 February 2013. Cite journal requires |journal= (help)
  5. ^ "International Organization of Legal Metrology: OIML". La métrologie française. Retrieved 5 February 2013.
  6. ^ a b "OIML Strategy" (PDF). OIML B 15 (2011 (E) ed.). Paris: Bureau International de Métrologie Légale. Archived from the original (PDF) on 2 December 2016. Retrieved 6 February 2013. Cite journal requires |journal= (help)
  7. ^ Agenda and Working Document (PDF). 14th International Conference on Legal Metrology. Bucharest, Romania: OIML. 3 and 4 October 2012. Retrieved 4 February 2013. Check date values in: |date= (help)
  8. ^ "OIML: Introduction and Structures". OIML. Archived from the original on 20 August 2013. Retrieved 3 February 2013.
  9. ^ "Organisations in Metrology: OIML". Netherlands: NMI. Archived from the original on 13 April 2013. Retrieved 6 February 2013.
  10. ^ "Practical information when visiting the BIML". OIML. Archived from the original on 8 March 2013. Retrieved 3 February 2013.
  11. ^ "CIML Past Presidents". OIML. Retrieved 2 June 2020.
  12. ^ "BIML Past Directors". OIML. Retrieved 2 June 2020.
  13. ^ "OIML Membership Information" (PDF). OIML. Archived from the original (PDF) on 3 July 2009. Retrieved 9 February 2013.
  14. ^ "OIML Database: Members". OIML. Archived from the original on 15 December 2009. Retrieved 4 February 2013.
  15. ^ "OIML Technical Committees and Subcommittees". OIML. Retrieved 2 June 2020.
  16. ^ "Catalog of OIML Publications". OIML. 2 June 2020. Retrieved 2 June 2020.
  17. ^ "Memoranda of Understanding (MoU)". OIML. Retrieved 2 June 2020.