Anyone driving a commercial vehicle for hire with a current CDL absolutely must have a valid medical card.. most states will even suspend your license if your medical card expires (Valid 2 yrs) while your CDL is current.. . I get a notice in the mail from the State every 2 yrs a month prior to its expiration.. They require a copy be entered into a data base.. In your case just getting the vehicle to the test site for him, I highly doubt you'll have any issues ..