This, 'Reaction times, motor skills, and the general perception of speed, time and distance are all impaired by marijuana use' of course makes sense-just as being a drowsy driver has similar negative affects.

With that said, being around a stoned person vs a drunk, give me the stoned one any day of the week. But not on the road behind the wheel for either one of them.

Dangerous enough when driving cold stone sober and wide-awake.