These days it's probably 90% certain that encouners with troopers are being recorded by video from the grill or dashboard of the vehicle.I've been wondering about that since being verbally abused by a cop in a small Nevada town a few years back. I'd kind of like to just keep a tape recorder with me on long trips and turn it on if pulled over. Do I have to notify the officer that I'm recording our conversation? Can he refuse my request? Is turning on the recorder going to piss him or her off and make things worse?
You might say something to the effect that you're pretty sure that the current encounter is being recorded by video device(s) located in the officer's car. Because the position of the officer next to your car often affords a bias in favor of the officer's portion of the conversation vs yours you might then mention that you've decided to record the conversation in order to augment any shortcomings that the officer's recording might have - lest there be any confusion should either of you elect to pursue the infraction in question in a court of law.
I always carry my microphone for my iPod in my car within easy access should I get pulled - especially if I'm in Nevada.