California Code, Business and Professions Code - BPC § 12500

(a) “Weighing instrument” means any device, contrivance, apparatus, or instrument used, or designed to be used, for ascertaining weight and includes any tool, appliance, or accessory used or connected therewith.

(b) “Measuring instrument” means any device, contrivance, apparatus, or instrument used, or designed to be used, for ascertaining measure and includes any tool, appliance, or accessory used or connected therewith.

(c) “Correct” means any weight or measure or weighing, measuring, or counting instrument that meet all of the tolerance and specification requirements established by the secretary pursuant to Section 12107.

(d) “Incorrect” means any instrument that fails to meet all of the requirements of Section 12107.

(e) “Commercial purposes” include the determination of the weight, measure, or count of any commodity or thing that is sold on the basis of weight, measure, or count; or the determination of the weight, measure, or count of any commodity or thing upon which determination a charge for service is based. Devices used in a determination upon which a charge for service is based include, but are not limited to, taximeters, odometers, timing devices, parcel scales, shipping scales, and scales used in the payment of agricultural workers.

“Commercial purposes” do not include the determination of the weight, measure, or count of any commodity or thing that is performed within a plant or business as a part of the manufacturing, processing, or preparing for market of that commodity or thing, or the determination of charges for the transmission of letters or parcels of less than 150 pounds, except when that determination is made in the presence of the customer charged for the service, or the determination of the weight of any animal or human by a qualified health provider, California-licensed veterinarian, licensed physician and surgeon, or staff members within the business operations of, and under the supervision of, a California-licensed veterinarian or licensed physician and surgeon for the purposes of determining the appropriate dosage of any medication or medical treatment or the volume, duration, or application of any medical procedure.