I am not exactly sure what the officer said, nor am I exactly sure of your situation, but the basic answer to the "is fighting illegal" question is this: every person has a right to defend himself or herself. The limit to that right is when you go beyond the amount of force necessary to defend yourself. For example, the old adage of bringing a knife to a gunfight is one that most of us know: the opposite scenario of bringing a gun to a knife fight would be an example of using more force necessary to defend yourself. You would be subject to a criminal charge under that set of facts that I used in my example. However, if your son fights to defend himself from a reasonable fear of an imminent threat of bodily harm then he did not commit a crime. I have had many cases involving a mutual fight and usually those cases are resolved favorably for the defendant ... although sometimes only after a jury has to sort it out.