Ohio Rev. Code § 4549.13: Marking and equipment for motor vehicle used by traffic enforcement officers.

Any motor vehicle used by a member of the state highway patrol or by any other peace officer, while said officer is on duty for the exclusive or main purpose of enforcing the motor vehicle or traffic laws of this state, provided the offense is punishable as a misdemeanor, shall be marked in some distinctive manner or color and shall be equipped with, but need not necessarily have in operation at all times, at least one flashing, oscillating, or rotating colored light mounted outside on top of the vehicle. The superintendent of the state highway patrol shall specify what constitutes such a distinctive marking or color for the state highway patrol.