Evo said:
It was explained to you why your link was not a scientifically valid sample as there were only 24 subjects. The information I posted to was ACTUAL reckless drivers, not some controlled study in The Netherlands.
The information you posted had only 150 drivers, and did not distinguish between "testing positive for" and actually being under the influence of marijuana, nor does it separate those who tested positive for marijuana from those who tested positive for alcohol and other drugs. All it shows is that 50 reckless drivers had smoked marijuana some time in the month prior to their arrest (which is to say that the odds are very good that a given reckless driver is *not* a marijuana user, and overwhelmingly good that said driver is not stoned at the time). Even if these glaring methodological errors were corrected, the result would only show that reckless drivers are slightly more likely to be stoned than the general population, not that stoned drivers are more likely to be reckless. A controlled study (using actual cars and roads and marijuana) is exactly what is called for if you want to determine the risks of driving under the influence of marijuana.
Call the sample size of 24 insufficient all you want: that work has been published in peer-reviewed journals, and was adopted by the US Department of Transportation as a basis for policy-making. Note that if you get 24 people, pump them full of alcohol, and then administer the same driving test, you'll have no trouble seeing the effects. If marijuana is similarly dangerous, why don't we see a similar outcome? I'm not sure why you're unhappy with a study done in the Netherlands, particularly considering that they have a much more rational, science-based approach to marijuana policy, but note that the study in question was commissioned by the NHTSA (National Highway Transportation Safety Association):
http://www.druglibrary.org/schaffer/misc/driving/driving.htm
Or here's another study from Britain:
http://www.newscientist.com/article.ns?id=dn2063
This Canadian study found that marijuana *improved* driving performance in some subjects:
http://www.sciencemag.org/cgi/content/abstract/186/4161/317
Many countries and researchers have gone looking for evidence of marijuana's contribution to driving fatalities, and nobody ever seems to find them. That (and the a-priori requirement that research outcomes should bolster anti-marijuana advocacy) is why you end up with wishy-washy statistics that don't apply to actual driving, don't measure marijuana intoxication and/or don't separate out the effects of other drugs.
Anyway, the point is not that it's a good idea to drive while stoned. It can't help your driving, is illegal, and so should be avoided, particularly if you've had anything to drink. But equating stoned driving it to drunk driving, as was done in the OP, is absurd.