People are supposed to be free to receive and interpret any electromagnetic waves that cross their property, or in public spaces. Cops are people. So, they should be free to receive and interpret to any electromagnetic waves to further law enforcement, and in fact they would be foolish and incompetent not to. If your radio waves are saying "I'm a criminal" that's no different than posting a sign outside your house saying the same thing. If you don't want that, don't emit electromagnetic waves.