The one large English-speaking country that successfully changed over to the metric system in the 1970s was Australia. Many Americans believe that what this country accomplished, and how they implemented it, could not be repeated in the US. My review of the historical record and from conversations with Australians who were present during the metrication period in Australia, leads me to the conclusion this is not true. We can follow their example, with very similar legislation. In fact we may not even need legislation.

The term voluntary was either deliberately or ignorantly misinterpreted when Australian metrication was discussed in the 1975 US Metric Hearings. It was asserted that Australia just nicely asked everyone to voluntarily become metric, and industry, government and everyone else all switched over in response. This is simply not the case. Here is how Kevin Wilks, author of Metrication in Australia explains what was meant by voluntary metric conversion:

In addition, the term “voluntary” meant that the [Australian] Metric Conversion Act of 1970 contained no penal clauses and that no new legislation would be enacted specifically to enforce metrication. Instead, the force of law would be achieved by amendment of existing State or Federal legislation to incorporate metric measurements whenever the measurements to be used in particular activities are specifically indicated.

The legislation did not contain any new penal clauses, but relied on the existing laws for enforcing weights and measures. These laws would now enforce the use of metric measurement, and penalize non-compliance as they had previously enforced imperial measures and punished non-compliance.

I will summarize the process as it might be accomplished in the United States, and then expand upon it. There would be two items:

1) Pass legislation making SI (the metric system) the only legal system in the US after a 5 year period.

2) Set up a metric board as Australia did that would identify economic sectors of the economy, create committees with recognized experts from each industrial sector (and sub-sectors). The metric board would interface with the committees as they  determined the best methods to change each industrial sector and/or sub-sectors to metric.

There are many misconceptions about the metrication process in Australia. Americans in the 1970s were told that Australian metrication was entirely voluntary. This was not true. The conversion to metric was mandatory, but the methods and policies used by private business was voluntary (i.e. the government would not dictate the methods, the best minds of each industry would caucus and decide).

What the Australians legislated was that metric would become the only legal measurement system after a given period of time. The regulatory and enforcement infrastructure was already in place to enforce weights and measures. After a certain date these agencies would demand that trade be done in metric under the same laws. If gasoline stations did not sell in metric units (of their choice) after a designated M-Day, then the same penalties that would be enforced if they were selling gallons which were of an incorrect amount would be enforced. This would be the case for the economy as a whole. This infrastructure exists in the US and would enforce and penalize those who did not comply with the law making metric the sole legal set of weights and measurements.

There are two ways the US could implement point number 1 above. First, in the 1975 metric hearings, the American Bar Association was of the opinion that it was possible no legislation was needed. The President of the United States could appoint a “Measurement Czar” and metrication could occur by executive order. The second option is for Congress to pass legislation designating that metric would be the law of the land after a period of say five years.

Again there are two options to achieve point number two (creation of a metric board), by executive order or congressional legislation. In either case, a useful guide exists which provides a template upon which to build. It is the monograph Metrication in Australia: A Review of the Effectiveness of Policies and Procedures in Australia’s Conversion to the Metric System. The Measurement Czar could create the same committees of industry experts and government liaisons to for industry to develop their methods of metrication and negotiate an M-Day for each sector/sub-sector of the nation (as was done in Australia).

The US Constitution gives the government the sole authority to determine the weight and measures used in the US. Article 1, Section 8, Clause 5 reads:

To coin Money, regulate the Value thereof, and of foreign Coin, and fix the Standard of Weights and Measures;

This authority is no different than that granted to Australia’s government. There is no reason it could not be exercised in the US, by the executive or legislative branches.

As stated previously, no new legislative penalties would be required, because an infrastructure for enforcement and regulation of the current usage of Weights and Measures exists. They would now be tasked with enforcing SI Weights and Measures. How each industry which is regulated would become metric would be voluntary.

All that is absent, is an executive order, or congressional legislation making SI the only legal system in the United States after a five year period. Both points 1 and 2 need to be implemented. Legislation without a metric board endowed with considerable authority and funding would only lead to uncertainty, and make a metric transition chaotic and prolonged.

President George Washington gave his first State of The Union Address on January 8,
1790 in Federal Hall in New York City. In this address he stated:

Uniformity in the currency, weights, and measures of the United States is an
object of great importance, and will, I am persuaded, be duly attended to.

They were not, and have not been.The inaction of Congress for over 230 years is the definition of “prolonged.” The Mendenhall Order was not legislation. Reality was bearing down on the nation, and  because of Congressional inaction, the nation’s metrologists had to make a decision to use metric as the only practical way forward as a basis for determining the values of our non-SI proxy units. It’s time for the Congress or the President to attend to the weights and measures of the US. And finally fix the weights and measures as Washington desired so long ago. He realized that lack of attention to weights and measures erodes the competitiveness of the US economy and impedes the numeracy of its citizens.