Just to relate an incident that happened yesterday, a friend (Nigerian) and I was on our way back home after dinner almost close to 11pm. Then comes by a police car stopping by to do a spot check on the car in the vicinity of the Sunway and Subang interchange, right in the middle of heavy flow of traffic that could deliberately call for an "accident".
The spot check took 25 mins and they refuse to let us go, and indirectly asked for "duit kopi". We were with our valid documents. Upon handing in the cash, they finally left and we continued our journey. Also, the policemen were clad in their uniforms and had their names but were not wearing their ID numbers on their uniforms.
Just a sharing and reminder, in case, if and ever you are caught by in such situations, always take down their ID number on their uniform and enquire which station they come from, so that you can make a report against them for violating one's right. The silver ID number worn on their uniform can cause them to feel vulnerable or at risk.