That happened to me once. The cops followed me a couple blocks to my mother-in-law's house where I was dropping off my baby daughter. A couple of young rookies out to harass anyone. I got into their face and told them they were full of crap. Also that I was enroute to a meeting with police commanders and captains, and that they would hear of this (I was a civilian working for the PD), and named names. They went pale, got back into their car and left pronto. There's good cops, and unfortunately some bad eggs.
In this town, you would have wound up dead. Not necessarily right there, but certainly eventually.