yea, I think that's pretty much true for most instances. witnesses have to be bystanders not involved in the accident. as for liability...all liability insurance will ever do is pay for the other person's car in an accident that is your fault, so you don't get sued. if it's their fault, their insurance pays for it. so, if his insurance company wont pay, you're screwed.
my advice, fight that mofo. if he's only 18 chances are you can say he's inexperienced and such, and it'll probably look that way. honestly, if you took picutres of the cars, crash scene, skid marks, weather, etc...you should win. however, your word against mine cases don't usually get a result in either person's favor...
