Is there an FAA Exemption to FAR 91.17(b) to allow for  

under medical care I'd have no concern.  However, on an offshore rig waaaay back in the early 80s a fellow who just arrived offshore and continuing his journey to his final rig destination offshore (a barge) on embarkation literally fell out of the helicopter and finally struggled aboard.  Well, ah, no.  Had the dispatch offload the helicopter, shutdown, had a word with the tool pusher and told them to sober him up (aka coffee etc., read go through the motions) and convince everyone all is well, and when the perp and all are satisfied, an hour later, off we all went.  Only time in 11 years had to exercise the option to democratize the "solution" to the problem.  His job, or mine, and we both kept them.  Not totally kosher, but common sense, sort of, has to prevail.

Fire away all ya mohdeern xphertss!