Everyone out there knows or should know that getting behind the wheel while drunk is a recipe for tragedy, but what about stoned drivers? Does puffing the pipe affect one's ability to drive safely on the roads?

KIRO-TV in Washington State intended to find out by setting up the state's first ever stoned driver obstacle course. The TV station gave three various-level pot smokers three-tenths of a gram of pot, got them to smoke it, and then set them loose on the obstacle course to examine their reaction times, driving mistakes and attention spans behind the wheel. The test subjects drove with a licensed instructor who had his own brake to ensure safety. The obstacle course was also supervised by a police officer.

Surprisingly, the results showed that most drivers were fine after three tenths, but started to drive dangerously and more erratically once the dosage was upped to nine-tenths of a gram. The moral of the story seems to be that pot impairment is less dangerous when behind the wheel than alcohol impairment, but intoxication is intoxication, and the safest way to drive is to stay sober behind the wheel.