El Maximo writes:

Actually, that question is completely irrelevant to the question posed.

No, it is not. The FAA is concerned about pilots who fly while drunk; it
doesn't care how many times they've been drunk in the past while not flying.
Their concern with DUI is to try to predict who is likely to become drunk
before flying today, not in the past. Since they cannot check every pilot
before every flight, they try to predict and move proactively.

If this prospective pilot no longer drinks, he should do what is necessary to
prove that to the FAA so that he can get his medical. If he still drinks, he
should think twice. Generally, one DUI is an extremely bad sign, and two
should logically be a showstopper, but there are exceptions to every rule (and
there are pilots who get drunk and kill themselves and others).