advice....just call their bluff and be taken to the magistrate. Unless he is also corrupt, usually not, you will get away with lost time and hassle. Los transitos won't even take if you did nothing wrong and they realize they won't be paying the mordida (bribe)

In other words, when people like you continue to pay, the next tourist also will be a vicitm of this scam. Do what I do when the transitos (not real police by the way) pull you over......run, elude them, and hide the car and leave it!!!!!!!!!! works everythime!