You can do a lot of things while high, but driving shouldn't be one of them.
The Colorado Department of Transportation released three drugged driving PSAs on Youtube yesterday. The gist? Residents can do lots of things while high, but driving isn't one of them.
As with most drug-related PSAs, the DOT spots perpetuate the dumb stoner stereotype. One guy tries to light a grill (but can't), another guy tries to play pickup basketball (but can't), and another guy tries to install an expensive flat-screen TV (but can't). You can try to do all these things legally, the PSAs say, but don't you dare drive.
For more on the unsettled frontier of measuring marijuana impairment, see this recent story from The New York Times.