At the very least, they tell you not to friggin drive for a while if there are potental issues. They even do it with OTC sleep med fer chrissake. With a prescription, if the doctor did not watch this very carefully, he committed malpractice.
If this was a med issue, the guy either ignored his doctor and drove when he shouldn't or neglected to mention earlier problems to his doc. Neither of these make him innocent. I'm normally more forgiving than most people here, but this guy needed to be more careful with what he took while driving, and his lack of care killed a man. No sympathy. This is of course assuming that the medication arguement is even true, though it smacks of BS.