California Code, Penal Code - PEN § 32406

(a) An individual who honorably retired from being a sworn peace officer, as defined in Chapter 4.5 (commencing with Section 830) of Title 3 of Part 2, or an individual who honorably retired from being a sworn federal law enforcement officer, who was authorized to carry a firearm in the course and scope of that officer's duties.  For purposes of this section, “honorably retired” has the same meaning as provided in Section 16690.

(b) A federal, state, or local historical society, museum or institutional society, or museum or institutional collection, that is open to the public, provided that the large-capacity magazine is unloaded, properly housed within secured premises, and secured from unauthorized handling.

(c) A person who finds a large-capacity magazine, if the person is not prohibited from possessing firearms or ammunition, and possessed it no longer than necessary to deliver or transport it to the nearest law enforcement agency.

(d) A forensic laboratory, or an authorized agent or employee thereof in the course and scope of his or her authorized activities.

(e) The receipt or disposition of a large-capacity magazine by a trustee of a trust, or an executor or administrator of an estate, including an estate that is subject to probate, that includes a large-capacity magazine.

(f) A person lawfully in possession of a firearm that the person obtained prior to January 1, 2000, if no magazine that holds 10 or fewer rounds of ammunition is compatible with that firearm and the person possesses the large-capacity magazine solely for use with that firearm.