I doubt that with maximum 32 people on the map you can not speed unless you are a cop....
that is unless someone made the unholy idea of an autosuspect...
Cops still have to abide by the rules that are found on the website (they get a link to it upon /duty), so if they choose to break it, and ignore your warnings, it's punishable. Could become a copban if done too often.
Also, when a cop is clearly not into anything related to his duty as a cop, and doing crimes on duty just for the sake of not getting suspected, report the player to admins. He is abusing the scripts for his own good (and gaining an advantage over others) so he will be punished, if sufficient evidence is gathered.