Under California law, you are justified in injuring or even possibly killing another person if you acted in self defense. There are several elements to self defense. You have to have a reasonable belief of imminent bodily injury or death. You also have to reasonably believe that immediate force is necessary to prevent the harm. Finally, you can only use reasonable force to defend yourself. Self defense is a complete defense to violent crimes including murder. As mentioned earlier, the threat must be immediate. If a person threatens to kill you tomorrow then self defense won’t apply. Under California law, you have no duty to retreat. Each jurisdiction has its own self defense laws which may include a duty to retreat but under California law there is no duty to retreat from your aggressor.