Bus. & Prof. Code, § 12602

(a) It is unlawful for any person engaged in the packaging or labeling of any commodity for distribution or sale, or for any person (other than a common carrier for hire, a contract carrier for hire, or a freight forwarder for hire) engaged in the distribution of any packaged or labeled commodity, to distribute or to cause to be distributed any such commodity if the commodity is contained in a package, or if there is affixed to that commodity a label, which does not conform to the provisions of this chapter or the regulations adopted under the authority of this chapter or the provisions of, or the regulations adopted under, Chapter 14 (commencing with Section 13400) or Chapter 15 (commencing with Section 13700).

(b) The prohibition contained in subdivision (a) does not apply to persons engaged in business as wholesale or retail distributors of commodities, except to the extent that those persons (1) are engaged in the packaging or labeling of such commodities, (2) prescribe or specify by any means the manner in which such commodities are packaged or labeled, or (3) have knowledge of the violation of any provision of this chapter or of Chapter 6.6 (commencing with Section 12665), Chapter 14 (commencing with Section 13400), or Chapter 15 (commencing with Section 13700).