In MD, you have to have tags that have the international wheelchair icon on it,
or a rear view mirror hanging card that is specifically handicap.
That comes with the issue of tags from the Dept of Motor Vehicles (state).
My son has not gone far enough in his therapy (less than 2 yrs post, injury-broken neck C-5) to consider him being able to drive a wheelchair equipped van with hand controls.
He doesn't have enough return in his hands, yet.
But many with his degree of severity of spinal cord injury, do drive.
The website I mentioned above is a fountain of information.