RCW 19.94.150: Standards recognized.

The system of weights and measures in customary use in the United States and the metric system of weights and measures are jointly recognized, and either one or both of these systems shall be used for all commercial purposes in this state. The definitions of basic units of weight and measure and weights and measures equivalents, as published by the national institute of standards and technology or any successor organization, are recognized and shall govern weighing or measuring instruments or devices used in commercial activities and other transactions involving weights and measures within this state.