I have a digital voice recorder, dash cam and a flip video recorder and I record all interactions with the police, on all at the same time. It is lawful to record public officials in the course of conducting their business in public. The side of the road is public. The inside of my moho or trailer is not public and will require a warrant to search. Research and understand your rights. Don't fall for the "if you have nothing to hide whats the problem?" line either. The police will usually ask you to stop recording them. I have used the "nothing to hide" line back on them. Some power drunk cops think they can abuse your rights at their whim. Record them even if they tell you to stop.