Cal. Food and Agricultural Code § 33351

It is unlawful for any person to do any of the following: (a) Prevent, interfere with, or attempt to nullify in any way the work of any duly authorized representative of the department or of an approved milk inspection service in the enforcement of any provision of this division. (b) Interfere with or prevent any such representative from examining or auditing any records or books in the conduct of his or her official duty. The records that are required to be made available include, but are not limited to, raw milk products purchased or received, daily production and manufacturing records, and all sales and distribution records maintained by the licensed milk products plant. (c) Prevent or interfere with any such representative if he or she deems it advisable to secure samples of milk or any product of milk, product resembling milk products, imitation butter, or oleomargarine, or any substance which is designed to be used as a substitute for milk or any product of milk.