No, California is not one of the U.S. states with a duty to retreat law. This means that there is no legal obligation for someone to retreat from an encounter as long as they are in a location where they are legally allowed to be.
In some cases, this may just mean that the person is in public. In many cases, it means that they are in their home or residence. If they face a physical threat from another individual, they can exercise their right to self-defense without the need to first seek a way to avoid the confrontation.
Does this include deadly force?
Yes, there are situations in which an individual can use deadly force to defend themselves, as long as a reasonable person would conclude that it was a prudent response and that they had a genuine fear of death or great bodily injury.
For example, if someone breaks into your home, you may be allowed to use deadly force to defend yourself or your loved ones. You can still use self-defense to justify these actions, and there is no need to retreat from your home just to avoid the confrontation.
That said, deadly force cannot be used in all situations. It could still be seen as an unnecessary escalation of violence in cases where you did not genuinely fear for your own life. The force used to protect yourself must be relatively similar to the force being used against you or the threat that you face.
You may find yourself facing charges for assault or related violent crimes when you believe you were just exercising your right to self-defense. In a situation like this, it is imperative that you understand all of your criminal defense options.