Legal metrology is originated from the need to ensure fair trade, specifically in the area of weights and measures. Legal metrology is primarily concerned with measuring instruments which are themselves legally controlled, and the main objective of legal metrology is to assure citizens of correct measurement results when used in official and commercial transactions.
OIML is the International Organisation of Legal Metrology. There are also many other areas of legislation, outside legal metrology, where measurements are required to assess conformance with regulations or legislation e.g. aviation, healthcare, construction products, environmental and pollution control.
Legal metrology comprises all activities for which legal requirements are prescribed on measurement, units of measurement, measuring instruments and methods of measurement. These activities being performed by or on behalf of governmental authorities, in order to ensure an appropriate level of credibility of measurement results in such socially important fields such as trade, health, environmental protection.
Legal metrology includes four main activities:
- setting up legal requirements,
- control / conformity assessment of regulated products and regulated activities,
- supervision of regulated products and of regulated activities, and
- providing the necessary infrastructure for the traceability of regulated measurements and measuring instruments to SI or national standards.
There are also regulations outside the area of legal metrology pertaining to the accuracy and correctness of measurement methods.