There are four hurdles that you must jump in order to be successful at self-defense. The first is that you must be able and willing to defend yourself when evil presents itself and puts you in a life-threatening situation. Second, you must actually beat your opponent to the point where the threat of death or great bodily harm has passed. Third, you must be cleared of all criminal charges and lastly you must be cleared of all civil charges.
Civil law is completely separate from criminal law but understanding the two is critical. It is possible that after being found not guilty or completely avoiding criminal prosecution altogether, that you will end up in civil court for wrongful death or injury to your attacker (assuming he survived). Should your attacker be killed, the attackers family can come after you in civil court.
In criminal court, the standards of evidence are high. It must be proven beyond a reasonable doubt that you did what you are accused of doing in order to be found guilty. In civil court, the standard is only “proven by a preponderance of evidence”. In other words, if the other side tells a better story than you do, you will probably lose the civil case. A perfect example of this is the OJ Simpson case where OJ was found not guilty of killing his wife in the criminal trial but was in fact found guilty in the civil case (wrongful death).
The law is structured in a way as to make it very difficult to harm another human and get away with it. When using deadly force to defend yourself, exercise great restraint and ensure your actions are justified under the law, as you will be held accountable.