(a) No person shall drive a commercial car or commercial tractor while his ability or alertness is so impaired by fatigue, illness or other causes that it is unsafe for him to drive such vehicle. No driver shall use any drug which would adversely affect his ability or alertness.
(b) No owner of a commercial car or commercial tractor, or a person employing or otherwise directing the driver of such vehicle, shall require or knowingly permit a driver in any such condition described in subsection (a) of this section to drive such vehicle upon any street or highway.
(ORC 4511.79)