we little serfs have every right to ask why we were stopped, and why we are detained....cops reason was the turn signal...but they instead went after the passenger......
I remember one video I saw, a woman questioned the cop why was she being detained, and was she free to go. Cop kept harassing her. She said why am I being detained, and I should be free to go or tell me why I'm detained. Finally she said contact your supervisor to explain why I'm being detained. Cop calls in, and the supervisor ordered him to not detain her. Some rookie cops are naive and don't understand the law; other cops are a-holes. One time I got incorrectly stopped by a pair of cops, and I verbally challenged them about what they were doing. Icing on the cake was telling these rookies they were delaying me from a meeting with some police brass at the Hall of Justice (true), they turned tail quick. I know good cops, but am aware of jerks who shouldn't be cops.
As far as failure to use turn signal or whatever it was goes. I have saw Officers driving police cars who did not use their turn signals when turning.