I work with kids who got in trouble with the law in milwaukee, usually municipal stuff. which i think this is all your son might get in trouble for. unless someone is suing you like the other boy's family (i doubt school would sue), i don't think you need a lawyer. did your son get a ticket? the worst it probably will be assault and battery. can anyone vouch for him that he jsut kicked the boy in the leg? if so, then it'll probably just be a disorderly conduct ticket, which is. since he did kick the boy, he is guilty. most judges will let him do community service to satisfy the ticket (well i should say milwaukee judges), if you want him to handle the consequence. you could always ask the judge about it. if he hasn't gotten a ticket yet, its kinda late. sometimes schools don't want to get the cops involved, bad PR. in terms of his record, judges that let kids do community service and if its his first ticket, he'll probably have it dismissed. even if its not dismissed, its just one ticket that'll get sealed to MOST people after he turns 18. (he'll still be able to get any job, and get into college)
let me know if you have any other questions. i'd be glad to help