California Code, Business and Professions Code - BPC § 12603

(a) The commodity shall bear a label specifying the identity of the commodity and the name and place of business of the manufacturer, packer, or distributor.

(b) The net quantity of contents (in terms of weight or mass, measure, numerical count, or time) shall be separately and accurately stated in a uniform location upon the principal display panel of that label, using the most appropriate units of both the customary inch-pound system of measure, and except as provided in subdivisions (c) and (d), the SI (Systeme International d'Unites) metric system.

(c) On a random package labeled in terms of pounds and decimal fractions of the pound, the statement may be carried out to not more than three decimal places and is not required to, but may include a statement in terms of the SI metric system carried out to not more than three decimal places.

(d) The requirements of subdivision (b) concerning labeling using the metric system do not apply to nonconsumer packages, foods that are packaged at the retail store level, or to the sale or distribution of products whose labels have been printed prior to February 14, 1994.

(e) This section shall become operative on February 14, 1994.