Legal and industrial metrology both have the same demands in terms of metrological traceability. This means that the measurement process must be defined and controlled. Under the specified conditions, the measurement process must produce a measurement result that the user can trust. The approach to the measurement process is the same in both disciplines: definition of the mesurand, selection of the most suitable measurement method, determination of the influencing parameters. All of these factors produce a result and an uncertainty that are compatible with the requirement. But the results of the metrological operation are put to different uses. In legal metrology, they are used to achieve regulatory conformity and to guarantee the conformity of the instrument with this regulatory requirement, so that it can continue to be legally used.

If the requirement is industrial (MPE), then users set their own limits of acceptability in order to meet a functional need. The end user must be capable of implementing the process as planned and analysed, since it often makes a significant contribution to the uncertainty of measurement. The concept of legal metrology encompasses the various aspects of the design, certification and inspection during operation of measuring instruments covered by a regulation. For more information, visit the French Ministry of Industry’s site at http://www.industrie.gouv.fr/portail/metrologie/index.php.