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Weights and Measures Act 1985 (Definitions of “Metre” and “Kilogram”) (Amendment) Order 2020

My Lords, this order was laid before the House on 16 March 2020. The purpose of this statutory instrument is to update the Weights and Measures Act 1985 with new definitions for the metre and kilogram units of measurement. I emphasise that this does not represent any change in policy; it is simply about updating the unit of measurement definitions in UK law to align with those agreed internationally. It ensures that UK legislation is in step with the rest of the world.

I emphasise that the values of the units of measurement themselves are not changing. A kilogram will weigh the same as it did before the definitions were amended and a metre length will also still be the same. Therefore, there will be no direct impact on business or consumers. Businesses will not need to change their weighing or measuring equipment and consumers will have no need to be made aware of the changes. Perhaps I may give some background for the aid of noble Lords, providing the context of the changes that have been made and the processes that sit behind them.

The new definitions have been approved by the International Bureau of Weights and Measures. Currently 102 countries, including the UK, are members or associated members of the bureau. In fact, the UK was a founding member in 1875, alongside France, India and the US, recognising, even then, the need for consistency and accuracy of measurement to support fair and effective international trade.

The UK has remained at the forefront of both legal and scientific metrology for over 140 years since the bureau was founded. The bureau’s key objective,

“to … be the coordinator of the world-wide measurement system, ensuring it gives comparable and internationally accepted measurement results”,

is relevant even today. It ensures that the International System of Units—also known as SI base units—is uniform and accessible for the purposes of international trade, high-technology manufacturing, human health and safety, protection of the environment, global climate studies and the basic science that underpins all of those.

An accurate and agreed standard is essential to ensure consistency in weights and measures across all these applications. For example, it is critical not only that medicines are measured accurately to ensure correct dosage, but that consumers of any goods sold based on measurement have transparency and get what they pay for. This is vital, as in the UK some £342 billion-worth of goods are sold based on the measurement of their quantity, equating to some £6.23 billion every week. In addition, £280 billion-worth of goods per year are weighed or measured at the business-to-business level.

Originally, the definitions to determine the value of a unit of measurement were based on physical standards. Historically these might have been references to parts of the human body, utensils, or amounts that animals could carry. In more recent times, the physical standards became more sophisticated. For example, until now the kilogram was defined by reference to a piece of platinum and iridium that was held in a vault near Paris. As the definitions have developed, they have moved away from physical standards, as those physical standards can deteriorate over time and become less accurate. Even the slightest dust or cleaning can lead to deterioration of the metal and affect accuracy.

Until now, the kilogram was the only remaining definition based on a physical standard. Following decades of discussion, scientific research and testing, the new definitions for seven base units of measurement were agreed and recognised by the International Bureau of Weights and Measures in November 2018. The new definitions were deemed by the bureau to come into effect on 20 May 2019. Under the EU withdrawal agreement, we are proposing to implement the definition changes on the same date as member states of the EU: 13 June this year.

The seven base units of measurement with these new definitions are the metre, kilogram, ampere, second, candela, mole and kelvin. The definitions that we are concerned with today are those of the metre and kilogram. The new definitions are based on a set of seven defining constants, drawn from the fundamental constants of physics and other constants of nature, from which the definitions of the seven base units are

deduced. For example, the value of a kilogram can now be determined from Planck’s constant, which remains accurate under all circumstances. It is interesting to note that the redefinition of the kilogram was made possible using technology developed here in the UK. The UK’s National Physical Laboratory, one of the leading national metrology institutes in the world, played a key part in the redefinition of the kilogram. This change ensures that unit of measurement definitions are scientifically robust and accessible to all globally. It also ensures uniformity and accuracy and will stand the test of time, because no dust or cleaning will affect them.

For the UK to stay in step with the rest of the world and meet our obligations under the withdrawal agreement, we have taken steps to amend our legislation. In September 2019, regulations amended the definitions for all seven of the SI base units in the Units of Measurement Regulations 1986 and made amendments to certain definitions in the Weights and Measures Act 1985. Those amendments, in Statutory Instrument 2019/ 1211, were made using powers under Section 2(2) of the European Communities Act 1972 and are timed to come into force on 13 June 2020.

The Weights and Measures Act also contains the definitions of the metre and kilogram units of measurement. I have been advised that amending them requires the use of powers provided for in the Weights and Measures Act itself. That is why this new statutory instrument is before your Lordships today: to amend the Weights and Measures Act definitions of the kilogram and the metre. This will ensure that all of the UK’s law is consistent and up to date, and that we are complying with the terms of the withdrawal agreement. Our intention is that this amendment should come into effect alongside the Weights and Measures Act 1985 (Amendment) and Units of Measurement Regulations 1986 (Amendment) Regulations 2019, which is SI 2019/ 1211. That will happen on 13 June this year.

To conclude, this statutory instrument is simply about making UK legislation consistent and up to date, reflecting the new scientific definitions that underpin the legal and scientific metrology framework. There is no policy change. This is simply a technical change to ensure that the UK is in step with the rest of the world and therefore meeting our obligations under the withdrawal agreement. I emphasise once again: there is no direct impact on businesses or consumers, and I commend this order to the House. I beg to move.

12.40 pm