As a civilian (absent a dire life-threatening situation), you can’t legally just trot out on the road and direct traffic.
Want a sobering picture of the Mothers Against Drunk Driving lobby? Go here:
http://teejaw.com/?s=drunk+driving&x=0&y=0
He’s a retired lawyer (and big time pro-gun advocate) who says that the current low BAC numbers ensnare far too many unimpaired drivers.
Where’s the pic?