Laws are different in every state. In Indiana and Kentucky you cannot have a scanner in your car.
The law in KY (Kentucky Revised Statutes 432.570) It states you
MAY carry a police scanner if the following conditions are met;
I'll even attach a copy of th "KRS" for hams who pass through KY
(a) An individual who is a retailer or wholesaler and in the ordinary course of his business offers such radios for sale or resale;
(b) A commercial or educational radio or television station, licensed by the Federal Communications Commission, at its place of business; or
(c) An individual who possesses such a radio, provided it is capable of receiving radio transmissions only and is not capable of sending or transmitting radio messages, at his place of residence; licensed commercial auto towing trucks; newspaper reporters and photographers; emergency management agency personnel authorized in writing by the director of the division of emergency management (for state personnel) or chief executive of the city or county (for their respective personnel);
a person holding a valid license issued by the Federal Communications Commission in the amateur radio service peace officers authorized in writing by the head of their law enforcement agency, Commonwealth's attorneys and their assistants, county attorneys and their assistants, except that it shall be unlawful to use such radio to facilitate any criminal activity or to avoid apprehension by law enforcement officers. Violation of this section shall, in addition to any other penalty prescribed by law, result in a forfeiture to the local law enforcement agency of such radio.
The provisions of this section shall not apply to a paid or volunteer member of a fire department or a paid or volunteer member of a public ambulance service licensed in Kentucky who has been given permission in writing by the chief of the fire department and the chief of each law enforcement agency whose frequency is to be monitored, or the director of the ambulance service and the chief of each law enforcement agency whose frequency is to be monitored, to possess a radio capable of receiving on a frequency allocated to a police department or law enforcement agency, whether the radio is in a vehicle or not.