Hm, sounds to me like she was in the wrong in several areas, first, i would say she was driving recklessly, failing to signal lane changes, and changing more than one lane at a time, which is a ticketable offense in most places, and she used fighting words (the finger) which is a form of speech not protected under the constitution and depending on where she is she could be arrested for that. But of course assault and battery really isn't the best counter to that (legally), she deserved worse though. Prolly one of those kids who was never told no when she was little.