Tennessee Code Title 55. Motor and Other Vehicles § 55-20-203

(a)(1) Every passenger contract carrier covered pursuant to § 55-20-201 shall employ only drivers who have been examined for hearing, vision and any medical condition or drug use, either legal or illegal, which could cause impairment while driving.

(2) The drivers must be reexamined every three (3) years to determine whether their hearing and vision are sufficient for operation of a commercial passenger vehicle and that no medical condition exists that would make them unsuitable for the employment.

(3) A minimum of twenty-five percent (25%) of the drivers of any covered passenger contract carrier shall be re-examined annually on a random basis for illegal drug use.