California Code, Business and Professions Code - BPC § 12611

It is unlawful to pack, ship, or sell any commodity in a container which does not conform to all the specifications of this chapter; or which is not conspicuously marked, branded, or otherwise labeled as required by this chapter; or on which any word, statement or other information required by this chapter is not prominently placed, in such terms and with such conspicuousness, as compared with other words, statements, designs or devices on the label or container, as to render it likely to be read and understood by ordinary persons under customary conditions of purchase and use.