Drunk pilots

If an aircraft is taxiing out from the ramp and controllers notice
that the pilot sounds obviously drunk, what can be done? In a car,
the cops can pull him over, but what do you do when a drunken pilot is
taxiing out for take-off? What do you do if he's already in the air?
And how does handling the situation differ between private pilots and
pilots transporting passengers for hire (such as airline pilots).

I know the FAA has occasionally pulled airline pilots off a plane when
they are drunk (apparently they have to wait until the pilot does
something that clearly demonstrates his intention to fly), but I
presume that someone or something tips them off in advance. What if
they don't find out about it in advance?

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