If our side strikes first before being harmed, causing serious injury or death to the other party, it does not fall within the scope of legitimate self-defense. Rather, it counts as preemptive defense. Legally, preemptive defense refers to defending against an unlawful act that has not yet begun. This type of defense is considered untimely, does not meet the conditions for legitimate self-defense, and is classified as excessive defense.
For instance, Zhang San saw a person coming towards him with a fruit knife on the street. Adhering to the principle of striking first, Zhang San decisively acted. He pulled out a handgun and killed the person with one shot. Not to mention the crime of illegal possession of firearms and ammunition, Zhang San's action counted as preemptive defense, a clear case of excessive defense.
