Gut reaction from pax.
30 years ago (or was it more - I'm getting old!) the culture was different, but I was a trifle nervous flying behind a driver who I had been with at an "airline party" the night before and who said "five to twelve, flight at 8 ack-emma, 5 minutes to the 8 hour rule" and downed an 8-ounce glass of Scotch in those 5 minutes.
Those days, we would sneak out of the party and remove the back wheels from his car if we thought maybe he'd kill himself if he drove home. Thoughts of "3rd parties" didn't occur to us those days. (Okay - we were a bit stupid, as well as "young and irresponsible", and pretty uninformed "way back then".
Don't happen these days!
If the guy had been a bit "over", but the circumstances were so muddied that it was hard for the cops to be sure of a conviction,may I suggest that he's "had a bl00dy good warning", and the best solution would be to let it drop and pretty surely be reassured that he's "had a good flea-in-the-ear" and surely will be more careful in the future, whether he's been on booze, illegal substances, or legal sleeping medication (not suggesting any of this might be the case).
IF he's innocent (for either not taking anything, or because he had no intention of "driving" that day), then it's a waste of the CPS costs to go any further.
My "humble" opinion is that it's gone on toooooo long. Whatever the truth, the whole issue shoudl be dropped if there's not been sufficient evidence found at this time. For the sake of the guy involved, his airline, and for the confidence of the public in air transport.
(signed, seat 31D)