Fortunately some research indicates that stoned driving is less cause for concern than drunk driving.

One study[1] has found that "THC's effects after doses up to 300 mcg / kg never exceed alcohol's at BAC's of 0.08 g %" and that "alcohol impaired performance relative to placebo but subjects did not perceive it", whereas "THC did not impair driving performance yet the subjects thought it had."

Another study[2] finds that "marijuana smokers tend to compensate effectively for their impairment by utilizing a variety of behavioral strategies such as driving more slowly, passing less, and leaving more space between themselves and cars in front of them", although it notes that the combination of marijuana and alcohol can impair even at doses that would be harmless for either drug alone.

[1] http://casr.adelaide.edu.au/t95/paper/s1p2.html

[2] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2722956/

My completely anecdotal experience in college amongst my friends was that, amongst people who used marijuana, they would drink far less when it was around.

I'm curious to see what will happen in Colorado regarding accidents caused by drunk driving and alcohol related crime in general. Will it go down measurably due to people substituting marijuana for booze?

Do you not think it's common now? Maybe the reason why we don't have such a stigma towards it (in terms of worry being talked about surrounding legalization) is because the reports of stoned persons killing people is less common?

Do you feel like you could back up this fear with data, proving the fear reality, or do you feel like it might be a fear of the unknown?

In Washington state, where we recently decriminalized marijuana use, the DUI standards for pot are actually much stronger than for alcohol. This is despite the fact that pot use doesn't impair driving ability in the same way as alcohol.

Moreover, people are already smoking pot, a lot, millions of people. Stoned driving is probably already about as common as it ever will be.

Is there even a good way to test if someone is high in the field like a breathalyzer? I have always been told if you don't admit they can't prove it.

Breathalyzers aren't good; they're convenient enough that courts ignore the fact that they aren't good. Same with drug dogs. They'll find a way to fake it.

http://www.popehat.com/2013/03/04/on-the-internet-nobody-kno...

http://www.duicentral.com/dui/the-dui-exception/

Aha, I was wondering how the cops and courts were going to keep up all that revenue they used to get from pot busts. Piss test roadblocks for everybody!

You should probably stay off the roads then. The good news is the data suggests the roads will become safer as more states legalize (stoned drivers are vastly more cautious than drunk drivers).

Does it depend on pot being legalised or not though? I'd believe people who want to smoke pot do it already.

If anything, I'd suspect the people who want to smoke but respect current pot laws would also respect DUI laws were pot legal.

Regardless how dangerous stoned driving is, it's not clear whether pot legalisation will increase usage. Moreover, I believe that legalising will allow for more prevention and control.