Quote:

because he would have been DRIVING illegally and breaking the law


It's illegal to provoke another motorist into an accident. You can't jam on your breaks for no good reason, other than to piss off another driver or to force them into an accident (think insurance fraud).

I believe the question is, was Brian a "proximate cause." Perhaps Mike Pornlaw can give a brief summary of Corey v. Havener in the multiple combined causes test for proximate cause.