From studies conducted, including the report you linked yourself, smoking cannabis is detrimental to driving, which is why it is illegal to drive high even in places where cannabis is legal.

Whether alcohol is worse isn't relevant to whether driving high should be legal, since drunk driving is also objectively detrimental and illegal therefore a comparison isn't a relevant argument to whether driving high should be allowed.


Have you watched this? All the subjects' driving got progressively worse with cannabis smoking. The reason the limit is low is because its conservative, some people are affected more quickly than others, but for obvious reasons the law doesn't want anyone to be dangerously high while behind the wheel.

Not only does this video contradict what youre saying its also not a good study, a sample size of 3 on an experiment with so many variables is not enough to draw a meaningful conclusion.



This blog post is a heavily biased "summary" of this study. I'm going to first talk about the study then about the blog post more generally.

The study

• The study uses a sample size of 18, this is really low for this type of study and its really difficult to draw meaningful conclusions from such a small sample size without contrasting the study to other similar studies which either agree or disagree with its conclusions. For context, commonly cited, similar studies of the effects of drugs generally have sample sizes in the hundreds or thousands; here are some reports on the effects of drinking for comparison:1 (2603 participants), 2 (2260 participants), 3 (16585 participants).
  
• The study also showed that cannabis did in fact negatively affect the driving of subjects. It found that the standard deviation of lane position (shortened to SDLP in the study) increased with cannabis use. "During drive blood THC ≥8.2 μg/L increased SDLP similar to notably-impairing alcohol concentrations." It's also worth noting that the participants were people who smoked between once every three months to 3 times a week (occasional smokers) and as such will have had higher tolerance to the effects of cannabis than much of the populous, of which a notable portion do not smoke or have never smoked cannabis.
  
• Again, the comparison between alcohol and cannabis isn't relevant to whether cannabis should be allowed when you're driving as alcohol is illegal when you are driving, but is relevant to the legalization of recreational cannabis use.

The Blog Post

• In this kind of context blog posts are worth avoiding, they are by nature highly biased as it is one person's opinion rather than being an actual study.
  
• "Coming out of the University of Iowa, the first study of its kind analyzed the effects of marijuana on driving performance. They found that driving under the influence of weed causes almost no impairment." Not only is this not the first study comparing the effect of marijuana on driving performance, they didn't find that driving under the influence of weed cased almost no impairment. This statement was objectively wrong on both counts.
  
• "In fact, the only impairment they did find was similar to that of the legal alcohol limit for drivers." Firstly, this directly contradicts the above statement made. Secondly, the study reported that impairment was proportional to the use of marijuana, so of course at a given blood concentration (8.2 μg/L) the negative effects of marijuana were seen to be "equivalent" to the negative effects of alcohol at a specific dosage.
  
• "As one would expect, impairment was found in all areas when weed was mixed with alcohol. Marijuana itself, however, showed no significant impairment to driving when taken in moderation. Some even argued that it made them drive safer and/or slower." This statement is also deliberately misleading; moderation is a subjective term, not one defined in the paper, I could argue in the same vain that alcohol when taken in moderation does not impair driving. The argument of what "moderation" is, is important to work out where to draw the legal limit but not to decide whether or not it should be legal to drive when high. The report itself at no point said that cannabis made any of the participants drive safer.

Blog posts like this are deliberately highly misleading, reading the study abstract is a better summary of what the report says than this by far. That's what the abstract is for!


I cant find the actual study that this article is about. But, again, it's about the comparison of alcohol to cannabis when driving, which isn't an argument that driving high should be legal because driving drunk is illegal so its a moot comparison. I could say that driving drunk is safer than driving while high on acid, and while probably true, it doesn't mean that driving drunk should be legal - because its dangerous.


So far the reports I've looked at from this thread have been from a Havard professor, commisioned by the WHO and from the university of Iowa. Both of these reports said that cannabis had a negative effect on driving. As "cannabis impairs psychomotor skills and cognitive functions associated with driving, including vigilance, time and distance perception, lane tracking, motor coordination, divided attention tasks, and reaction time."


I'm not going to critique this one, I actually do think weed should be legal, but definitely not driving high.

I also find it interesting that in one post you say this:


And in the very next post 3 of your 4 sources are media articles, and the last one is a deliberately badly written blog post designed to be misleading.


Edit: Fixed quote bbcode