His for criminal damage to property and possible reckless endangerment, and yours for following too closely or failure to slow to avoid an accident. You should always follow the 2 second rule, which will allow you slow your vehicle in time to avoid an accident. If you are driving a significantly heavier vehicle than that which is in front of you, logic and common sense dictate that you should increase your distance beyond the 2 second rule.
In my case, the 2 second rule didn't apply, as I was not in the same lane as the person that I rear-ended. He invaded my lane (illegally), though I don't personally fault him for trying to avoid a Pontiac Transport doing 360's down the interstate at 45+ MPH....
