Eons ago I was leading a trip, and one of the people was a teenage girl. Someone drove up alongside her and started hassling her, and it built up to where they tried to run her off the road. She rode onto the grass verge, and finally escaped, but only after he drove up after her.

As luck would have it, a police car came by while we were still talking about it. Though the car was gone, I had the plate number, and relayed the info to the officer. He said that he probably couldn't do anything, EXCEPT that the car tracks in the mud made a case for intent. After a few minutes of radio back and forth, they jumped into action, and sent a car to beat the driver home, and arrest him for assault.

The story ended well, with the DA saying it would be difficult to prosecute, and he'd have to plea bargain it, but would make sure the guy had big time legal fees for the process, so even with a fine and suspended sentence, he's still pay for his actions.