NORML's Paul Armentano has prepared a scientific review of over a dozen studies evaluating marijuana's effect on psychomotor skills and the risks posed by marijuana intoxication behind the wheel. Armentano finds that marijuana impairment is generally "subtle and short-lived," falling far short of the threats posed by drunk driving.
Although acute cannabis intoxication following smoking has been shown to mildly impair psychomotor skills, this impairment is seldom severe or long lasting. In closed course and driving simulator studies, marijuana’s acute effects on psychomotor performance include minor impairments in tracking (eye movement control) and reaction time, as well as variation in lateral positioning, headway (drivers under the influence of cannabis tend to follow less closely to the vehicle in front of them), and speed (drivers tend to decrease speed following cannabis inhalation). In general, these variations in driving behavior are noticeably less consistent or pronounced than the impairments exhibited by subjects under the influence of alcohol. Also, unlike subjects impaired by alcohol, individuals under the influence of cannabis tend to be aware of their impairment and try to compensate for it accordingly, either by driving more cautiously or by expressing an unwillingness to drive altogether. [see original for citations]Of course, the point here isn’t that one should get stoned and cruise the strip blasting Led Zeppelin. But this is information one would want if they were trying to create a smart marijuana policy as opposed to the disgraceful mess of legislative lunacy currently passing for marijuana law in America.
Whenever someone claims that marijuana makes you sick or crazy; that it will cause you to crash your car, kill your comrades, or catastrophically co-opt your common sense, just look for the corpses. Where are they? I've looked high and low, but I can't find the disastrous consequences of marijuana use apparent anywhere other than the Drug Czar's predictably propagandized press releases.
But to be fair, there are two horrible things about marijuana that everyone should be mindful of and they are as follows: 1) the smell attracts cops, nosy neighbors, and mooches and 2) the stuff remains detectable in your system for up to a month, thereby enabling various authorities to become needlessly aware of your activities.
If not for these two unfortunate conditions, the marijuana war wouldn't even begin to work, and the blockheads who've been bothering to fight it would've wandered off decades ago.