Here in Pennsylvania, the person that put the kitten in a toolbox would probably have been charged with cruelty to an animal and the act may have been considered as torture. Worse case scenario, the person would have been charged with a first degree misdemeanor and issued a citation, along with a subpoena stating a date and time to appear before a district judge for sentencing. He would not have been jailed. If the defendant pleads guilty or no contest, more than likely, he would be fined about $500.00 + costs and released. No jail time for the first offense. (And depending on the severity of the act.)
Your son being involved in an altercation and if it was in a public place, the arresting officer would have had choices here in PA. He would probably not have been jailed, but issued a subpoena to appear before a district judge for adjudication. Depending on the severity, the judge would have had several options. The arresting officer could have filed a complaint on different charges, ranging from: fighting in public, harassment, disturbing the peace, assault, along with a few other charges. The officer could have charged him with none, one or any number of charges. If the judge sees it as a felony, the price of the fine goes up. The plaintiff could have also filed a complaint and if he was injured to the point whereby, he was in need of medical aide or attention, he could file a lawsuit to recover any loss of wages or out pocket expenses for his medical bills, plus maybe a little for pain and suffering.
Something so simple as being involved in a brawl and being the aggressor may become a very expensive event for the defendant. It is always best to keep in mind that just because a person is doing something that you think he shouldn't be doing never gives the person the right to take the law into his own hands and dish out justice. Just to be clear, I am speaking about incidents such as this, not if someone comes across a woman being raped or someone that is put into a life threatening situation.