Cal. Civil Code § 3342

(a) The owner of any dog is liable for the damages suffered by any person who is bitten by the dog while in a public place or lawfully in a private place, including the property of the owner of the dog, regardless of the former viciousness of the dog or the owner’s knowledge of such viciousness. A person is lawfully upon the private property of such owner within the meaning of this section when he is on such property in the performance of any duty imposed upon him by the laws of this state or by the laws or postal regulations of the United States, or when he is on such property upon the invitation, express or implied, of the owner. (b) Nothing in this section shall authorize the bringing of an action pursuant to subdivision (a) against any governmental agency using a dog in military or police work if the bite or bites occurred while the dog was defending itself from an annoying, harassing, or provoking act, or assisting an employee of the agency in any of the following: (1) In the apprehension or holding of a suspect where the employee has a reasonable suspicion of the suspect’s involvement in criminal activity. (2) In the investigation of a crime or possible crime. (3) In the execution of a warrant. (4) In the defense of a peace officer or another person. (c) Subdivision (b) shall not apply in any case where the victim of the bite or bites was not a party to, nor a participant in, nor suspected to be a party to or a participant in, the act or acts that prompted the use of the dog in the military or police work. (d) Subdivision (b) shall apply only where a governmental agency using a dog in military or police work has adopted a written policy on the necessary and appropriate use of a dog for the police or military work enumerated in subdivision (b).