There is at least 1 "shoot across the street" LASER based (IIRC) system but there are "issues". There's no way to evaluate how the vehicle was operated prior to the "shot" nor is there a provision for weather (maybe not as big an issue in CA). Did they shoot you when you were accelerating, decelerating, or cruising - and prove it in a court of law. As I understand it, the system was actually developed for use on a test track where there is some control over the driving mode and measurements simply aren't taken in certain weather conditions. Unless the State Of California is fond of lawsuits I'd stay away from that one.

Dan