California Code, Penal Code - PEN § 11106.4

(a) Every law enforcement agency shall develop, adopt, and implement written policies and standard protocols pertaining to the best manner to conduct a “welfare check,” when the inquiry into the welfare or well-being of the person is motivated by a concern that the person may be a danger to himself or herself or to others. The policies shall encourage a peace officer, prior to conducting the welfare check and whenever possible and reasonable, to conduct a search of the Department of Justice Automated Firearms System via the California Law Enforcement Telecommunications System to determine whether the person is the registered owner of a firearm.

(b) For purposes of this section, “reasonable” as used in subdivision (a) means that the officer could conduct the firearm registry check without undue burden on the execution of the officer's other duties, that there are no exigent circumstances demanding immediate attention, and that the peace officer has access to, or can reasonably ascertain, relevant identifying information.