California Code, Penal Code - PEN § 20160

(a) Any imitation firearm manufactured after July 1, 2005, shall, at the time of offer for sale in this state, be accompanied by a conspicuous advisory in writing as part of the packaging, but not necessarily affixed to the imitation firearm, to the effect that the product may be mistaken for a firearm by law enforcement officers or others, that altering the coloration or markings required by state or federal law or regulations so as to make the product look more like a firearm is dangerous, and may be a crime, and that brandishing or displaying the product in public may cause confusion and may be a crime.

(b) Any manufacturer, importer, or distributor that fails to comply with this advisory for any imitation firearm manufactured after July 1, 2005, shall be liable for a civil fine for each action brought by a city attorney or district attorney of not more than one thousand dollars ($1,000) for the first action, five thousand dollars ($5,000) for the second action, and ten thousand dollars ($10,000) for the third action and each subsequent action.