
Quoting
Justified Force
Well obviously Joe would be in the wrong when he continues to beat on Steve after Steve is no longer a threat. However, I don't see why Joe would be charged if he were to stop once Steve stops. After all, the intent of self defense is not to kill, not to injure, but to stop. If you're intent is to stop than it clearly would be a case of self defense, I would think. To continue to beat on an attacker after they're no longer a threat would show that your intent goes beyond stopping them which would cross the line so that it would no longer be self defense but excessive force.
Self defense isn't supposed to be a get out of jail free card. Its supposed to be a not go to jail in the first place card. Self defense is a right and therefore it shouldn't get you thrown in jail any more than exercising any other right such as breathing.