California Penal Code
Title 8. Of Crimes Against the Person
Chapter 1. Homicide
Any person using force intended or likely to cause death or great bodily injury within his or her residence shall be presumed to have held a reasonable fear of imminent peril of death or great bodily injury to self, family, or a member of the household when that force is used against another person, not a member of the family or household, who unlawfully and forcibly enters or has unlawfully and forcibly entered the residence and the person using the force knew or had reason to believe that an unlawful and forcible entry occurred.
As used in this section, great bodily injury means a significant or substantial physical injury.