Weights and Measures Acts (UK) facts for kids

The informal public imperial measurement standards erected at the Royal Observatory, Greenwich, London, in the 19th century: 1 British yard, 2 feet, 1 foot, 6 inches, and 3 inches. The inexact monument was designed to permit rods of the correct measure to fit snugly into its pins at an ambient temperature of 62°F (162⁄3°C).

Bronze Yard No.11, the official standard of length for the United States between 1855 and 1892, when the Treasury Department formally adopted a metric standard. Bronze Yard No.11 was forged to be an exact copy of the British Imperial Standard Yard, which was ruined in 1834 during the Burning of Parliament. Both were line standards: the yard was defined by the distance at 62°F between two fine lines drawn on gold plugs (closeup, top) installed in recesses near each end of the bar.

A helium–neon laser at the Kastler-Brossel Laboratory at Univ. Paris 6. Britain's metric and imperial units of length and volume are now all ultimately derived from measurements of the speed of light in vacuum.

Before the 2019 redefinition of the SI base units, Britain's units of mass were derived from national standards periodically reverified against the platinum and iridium international prototype of the kilogram stored beneath two bell jars in a basement vault at the International Bureau of Weights and Measures's headquarters at Pavillon de Breteuil in Paris. A display replica shown at Paris's Cité des Sciences et de l’Industrie shown here. The modern kilogram is defined by a fundamental property of matter.

Weights and measures acts are acts of the British Parliament determining the regulation of weights and measures. It also refers to similar royal and parliamentary acts of the Kingdoms of England and Scotland and the medieval Welsh states. The earliest of these were originally untitled but were given descriptive glosses or titles based upon the monarch under whose reign they were promulgated. Several omnibus modern acts are entitled the Weights and Measures Act and are distinguished by the year of their enactment.

Background

There have been many laws concerned with weights and measures in the United Kingdom or parts of it over the last 1,000 or so years. The acts may catalogue lawful weights and measures, prescribe the mechanism for inspection and enforcement of the use of such weights and measures and may set out circumstances under which they may be amended. Modern legislation may, in addition to specific requirements, set out circumstances under which the incumbent minister may amend the legislation by means of statutory instruments. Prior to the Weights and Measures Act 1985, weights and measures acts were only concerned with trade law where the weight or size of the goods being traded was important. The 1985 act, however, had a broader scope, encompassing all aspects covered by the European Economic Community (EEC) European Commission directive 80/181/EEC.

As of 25 April 2012, the current primary legislation in the United Kingdom is the 1985 Act, which was last amended by statutory instrument in 2011. Statutory instruments made under the authority of the Act do not amend the Act per se, but regulate particular areas covered by the Act.

The Act is currently enforced by the 200 Trading Standards Offices managed by local authorities around the country. Definitions of units of measurements and the technical equipment relating to weights and measures are provided by the National Measurement Office, an agency of the Department for Business, Innovation and Skills.

Statute measure

Historically, many units had various customary definitions—by locality or trade, for example. Where these units also had a standard, legally defined definition, such as given in a weights and measures act, this was known as the statute measure. So a land area might be given as 24 acres—statute measure, to clarify that it was the acre defined in statute, rather than a customary acre of a different size, that was being used. Units that had statute-defined measures as well as customary measures were the acre, mile, perch, pole and ton. The level of legal enforcement of statute measures achieved between the mid nineteenth and the beginning of the twentieth centuries meant that only "statute mile" and "statute ton" needed qualifying beyond then. The statute mile still needed to be differentiated from the nautical mile, but the others, and the term "statute measure" itself, are now only used in a historical context.

Metric units of measure

The Weights and Measures Act 1897 provided that metric units could be used in addition to the traditional imperial units for purposes of trade. In practice, the actual choice of units was restricted by price marking orders which listed packaging sizes and pricing structures that might be used in specific circumstances. For example, as of April 2012, wine for consumption on premises may only be sold in 125, 175, and 250 mL glasses while draught beer may only be sold as 1⁄3, 1⁄2, or 2⁄3 pint and integer multiples of 1⁄2 pint. Prior to 1973, when the United Kingdom joined the EEC, such specifications were almost all in imperial units.

As part of its attempt to harmonise units of measure between the member states of its Internal Market, the European Commission (EC) issued directive 80/181/EEC which set out the units of measure that should be used for what it called "economic, public health, public safety, and administrative" purposes. To comply with this directive, the Weights and Measures Act 1985 extended the scope of Trading Standards responsibilities from just matters related to trade to all aspects of the directive. For example, it was the Trading Standards Office that criticised the use of sub-standard weighing machines in NHS hospitals.

To help ease the EC's desired transition from sole use of imperial units to sole use of metric units, the directive permitted the use of what were termed "supplementary indicators"—the continued use of imperial units alongside the metric units catalogued by the directive (dual labelling). The initial intention was to prohibit dual labelling after the end of 1989, with metric units only being allowed after that date. This deadline was later extended: first to the end of 1999, then to the end of 2009. Finally, in 2007, the European Union (EU, as it had become) and the EC confirmed that the UK would be permitted to continue indefinitely to use imperial units such as pints, miles, pounds and ounces as at present. The Gloucestershire County Council Trading Standards Department confirmed the EU ruling that the previous deadline for ending dual labelling had been abolished.

There are still a few cases where imperial units are required to be used and where metric units are not permitted within the scope of the Weights and Measures Act, such as the pint for the sale of draught beer and cider, and miles and yards for distances on road signage. Milk in returnable containers may be sold by the pint and the troy ounce may be used for the sale of precious metals. In addition, British law specifies which non-metric units may be used with dual labelling (for example the imperial gallon, but not the US gallon).

See also

• Other weights and measures acts