My son just turned 15 yrs old in October and yesterday hit a kid at his high school after the other kid threatened my son then approached my son yelling at him while he invaded my son's personal space by putting his face about 6 inches from my son's face. My son felt threatened that the other kid was going to hit him so my son punched the kid when the other kid lunged his head toward my son as if to headbutt. My son swung at him as my son was moving back as a means of defending himself. Can I be sued for my sons actions? Can I counter sue because the other kid attempted to harm my son?