Any officer arresting, or participating or assisting in the arrest of, a person charged with violating the motor vehicle or traffic laws of the city, provided the offense is punishable as a misdemeanor, such officer being on duty exclusively or for the main purpose of enforcing such laws, is incompetent to testify as a witness in any prosecution against the arrested person if the officer at the time of the arrest was using a motor vehicle not marked in accordance with R.C. § 4549.13.
(ORC § 4549.14)