For whatever its worth, Tennessee has a law that if a person uses a gun in self defense, no crime has occurred.
A man was going to his bank in Memphis recently when a bank robber emerged, running towards this man as he was getting out of his car, and pointing a gun at the man. He drew a .357 Magnum from his car and shot the bank robber grave yard dead. The bank customer had no carry permit, but as the shooting was ruled self defense, no charges were filed against the man.
But the man was a convicted felon, and was charged by Federal laws.