Cal. Penal Code § 25135
(a) A person who is 18 years of age or older, and who is the owner, lessee, renter, or other legal occupant of a residence, who owns a firearm and who knows or has reason to know that another person also residing therein is prohibited by state or federal law from possessing, receiving, owning, or purchasing a firearm shall not keep in that residence a firearm unless one of the following applies: