C.R.S. § 42-4-231

When lighted lamps are required by section 42-4-204 , no vehicle shall be driven upon a highway with the parking lights lighted except when the lights are being used as signal lamps and except when the head lamps are lighted at the same time. Parking lights are those lights permitted by section 42-4-215 and any other lights mounted on the front of the vehicle, designed to be displayed primarily when the vehicle is parked. Any person who violates any provision of this section commits a class B traffic infraction.