Although state specific laws vary from state to state when defining your legal right to use force to protect yourself, your home, your property and other people, most states’ laws require that any use of force be “reasonable for the circumstances.” That is, in addition to any specific rules outlined in statutory or case law, any individual who uses force must pass the “reasonable person” test.
The purpose of the reasonable person test is to give the jury a uniform standard when looking at the actions of each party in a case. While it's up to the jury to decide what's reasonable in any given situation, they will evaluate behavior based on an objective, reasonable person. In today's world, that can be very scary since we are such a divided nation on so many issues.
The term “deadly force” means a level of force which is likely to cause, or could cause, the death of another person, regardless of whether that person does die. Therefore, the prosecutor gets to decide whether he or she thinks death could have resulted and whether the deadly force rules should apply. That is why DEADLY FORCE should only be used as an absolute last option. The legal, financial and moral cost that you will encounter will change your life forever!
The best option to avoid such an unfortunate outcome is heightened situational awareness in hopes of avoiding such a situation.