California Code, Penal Code - PEN § 17730

(a) The sale to, possession of, or purchase of any weapon, device, or ammunition, other than a short-barreled rifle or a short-barreled shotgun, by any federal, state, county, city and county, or city agency that is charged with the enforcement of any law for use in the discharge of its official duties.

(b) The possession of any weapon, device, or ammunition, other than a short-barreled rifle or short-barreled shotgun, by any peace officer of any federal, state, county, city and county, or city agency that is charged with the enforcement of any law, when the officer is on duty and the use is authorized by the agency and is within the course and scope of the officer's duties.

(c) Any weapon, device, or ammunition, other than a short-barreled rifle or a short-barreled shotgun, that is sold by, manufactured by, exposed or kept for sale by, possessed by, imported by, or lent by, any person who is in the business of selling weapons, devices, and ammunition listed in Section 16590 solely to the entities referred to in subdivision (a) when engaging in transactions with those entities.