The problem with the "justice system" is though that if there's no way for the victim to prove the assault, then the "justice system" is 100% impotent. That, however, does not mean the assault did not take place. Having said that, obviously there shouldn't be mob justice, and having the power to destroy someone's life simply by accusing them is a dangerous thing.
So what's the solution, then? Victims of sexual assault and rape should just shut up, after they've gone to the police, who have told them that there's nothing to be done? Just go home and live with it? That doesn't seem right, either.