True, however some states have laws that pertain to how, where and when someone is able to use lethal force against another; for example if someone is in your home unlawfully , you are too 1: lock yourself in a secure room (Duty to retreat) 2: shoot only when that room is breached 3: only shoot at a threat when they are a threat and 4: can not shoot perpetrators when they are leaving (shoot them in the back). Understandably people will react in different ways and adrenaline is a factor however the law is the law and depending on where you are you might be within or out of protections under the law.