page_title: Metrication in the United Kingdom
section_title: Weighing machines
hierarchical_section_title: Metrication in the United Kingdom / Regulatory aspects / Weighing machines
caption_attribution_description: English: Analytical balance type EG from production company Kern Čeština: Analytické předvážky, EG firmy Kern
context_page_description: Metrication in the United Kingdom, the process of introducing the metric system of measurement in place of imperial units, has made steady progress since the mid–20th century but today remains equivocal and varies by context. Most of government, industry and commerce use metric units, but imperial units are officially used to specify journey distances, vehicle speeds and the sizes of returnable milk containers, beer and cider glasses. Imperial units are also often used to describe body measurements and vehicle fuel economy. In schools metric units are taught and used as the norm. Imperial units that remain in common usage in the UK are also taught.
  Adopting the metric system was discussed in Parliament as early as 1818 and some industries and even some government agencies had metricated, or were in the process of metricating by the mid-1960s. A formal government policy to support metrication was agreed by 1965. This policy, initiated in response to requests from industry, was to support voluntary metrication, with costs picked up where they fell. In 1969 the government created the Metrication Board as a quango to promote and coordinate metrication.
context_section_description: During the 1990s, a series of statutory instruments relating to weighing devices and to the sale of pre-packaged goods were issued to ensure that United Kingdom law on metrology was harmonised with that of its EEC partners. In line with EEC practice, the meaning of weights displayed on pre-packaged goods was changed in 1980 to show the average weight of each item in the batch rather than the guaranteed minimum weight of each individual item. The EU Measuring Instruments Directive (Directive 2004/22/EU) which intends to create a common market for measuring instruments across the countries of the EU came into force on 30 October 2006 with a ten-year transition period.
  The EU non-automatic weighing instrument directive (directive 2009/23/EC), which came into force in 2009 and was superseded by directive 2014/31/EU, codified existing regulations regarding the harmonisation of non-automatic weighing devices used for trade, medical purposes or in the preparation of evidence to be heard in court. The directive identified four classes of weighing device ranging from Class I (having a minimum accuracy of 1 part in 50,000) to class IIII (sic) (having a minimum accuracy of 1 part in 100). Devices that fall within the scope of the directive are required to be recalibrated at regular intervals and to have an output showing SI units, except for those used for weighing precious metals or stones. Secondary indications may be shown, provided that they cannot be mistaken for primary indications.
  The impact of this directive in the United Kingdom is that most traders cannot legally use weighing devices calibrated in units other than SI units. In 2000, after the deadline for the cessation of selling loose produce by imperial units had passed, some traders continued to sell produce from their market stalls using imperial-only scales. They were variously prosecuted for using unlawful scales, giving short measure and failing to display unit price per kilogram. Five traders, who became known as the Metric Martyrs, appealed unsuccessfully to the High Court, were refused appeal to the House of Lords, and appealed unsuccessfully to the European Court of Human Rights (ECHR).
  A LACORS report published in March 2010 highlighting widescale use of inappropriate scales in hospitals, sometimes of domestic quality, recommended that on safety grounds NHS hospitals should use Class III (or better) metric-only scales. A Department of Health alert was subsequently sent to all NHS trusts endorsing these recommendations.
caption: A Class II laboratory scale (accuracy 1 part in 22,000) with a calibrator's and CE stickers fixed to its side.
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