An upstream vehicle detection system captures images of a vehicle as it travels through a high occupancy vehicle (HOV) lane or high occupancy vehicle tolling (HOT) station and generates an hypothesis as to whether the vehicle is complying with HOV or HOT rules based on image analysis. A database of historical information about various vehicles' compliance with HOV or HOT rules is consulted to determine whether the vehicle has previously been identified as a potential violator and pulled over by law enforcement as a result. If the vehicle was previously pulled over by law enforcement and determined to be complying with HOV or HOT rules (a false positive), then the violation hypothesis may be weighted in favor of not pulling the vehicle over.