You are seriously misstating the legal standard for use of deadly force. In order for someone to lawfully use deadly force in self defense, they have to possess a reasonable belief that there is an imminent threat of death or gross bodily injury. As in, someone is already using deadly force or is threatening to. In certain circumstances and jurisdictions, there are additional requirements such as the duty to retreat. And there are rules like the fleeing felon rule that only apply in rare circumstances. But in no American jurisdiction is it sufficient justification to use deadly force merely because someone feels like a life is threatened.
Imminent and reasonable reduce to feeling rather easily. As an exercise, could you cite cases where reasonable and imminent were found to not be justified in case law?
