>Another perspective - what if they just followed cars leaving those bars and clubs for 1 mi., then returning and starting over after observing the driver's beh

>Another perspective - what if they just followed cars leaving those bars and clubs for 1 mi., then returning and starting over after observing the driver's behavior? You might notice someone being completely drunk that way, but not someone who's just moderately drunk reacting 10 times slower; unless something happens, of course, but you don't want that either.