The level of alchol in the blood to render someone drunk is so small that a sniff of the barmaids apron is likely to send you over the limit. The fact of the matter is that if you drink the night before the chances are that person will be over the drink/fly limit at 9am.The amount required to do this is minute compared with the drinkdrive limit which also in my opinion is pretty strict compared with other european states.I would bet my pension that the Captain involved had no idea he was over the limit as like many of us we believe we are clear of all traces of alchol because we have been to bed and it's now a new day. A pilot would never think of drinking at 9am in the morning if he had a 8pm checkout yet we all fall into the trap of drinking the night before no matter how little as tomorrow is another day.
Just a thought!