I know a guy who grew up in Cali. When he was young he got pulled over for speeding. The ticket got thrown out of court because the CHP officer was not wearing his cover and thus "Out of Uniform".
I was watching COPS with him once and down in Texas I think some guy was not letting the cops in to his apartment and I commented that I would not either- they were not wearing their hats and had no badges! All they were wearing were shirts with police written on the sleeve and guns. I guess thats common in some places but here in NY they have badges or if they are State Troopers a really complicated quasi-military uniform.