15 U.S. Code § 204 - Metric system authorized
It shall be lawful throughout the United States of America to employ the weights and measures of the metric system; and no contract or dealing, or pleading in any court, shall be deemed invalid or liable to objection because the weights or measures expressed or referred to therein are weights or measures of the metric system.
R.S. § 3569 derived from act July 28, 1866, ch. 301, § 1, 14 Stat. 339.
Pub. L. 90–472, Aug. 9, 1968, 82 Stat. 693, authorized the Secretary of Commerce to conduct a program of investigation, research, and survey to determine the impact of increasing worldwide use of the metric system on the United States; to appraise the desirability and practicability of increasing the use of metric weights and measures in the United States; to study the feasibility of retaining and promoting by international use of dimensional and other engineering standards based on the customary measurement units of the United States; and to evaluate the costs and benefits of alternative courses of action which might be feasible for the United States. The Secretary was directed to submit to the Congress such interim reports as he deemed desirable, and within three years after Aug. 9, 1968, a full and complete report of the findings made under the study, together with such recommendations as he considered to be appropriate and in the best interests of the United States. By its own terms, the Act expired thirty days after the submission of the final report.