Marijuana's psychoactive properties have never been in dispute. Whether those properties should be seen as risks or benefits will always be in dispute, due to the puritanical tendencies of its detractors. Science, however, prefers statistics over anecdotal opinions, and the numbers show beneficial correlations.
A study published in the American Journal of Public Health has shown correlation between states with legalized medical marijuana and a decrease in the suicide rate for men in those states. The authors of the study analyzed 17 years worth of statistics in states where medical marijuana was legal from 1990 to 2007. For the control group, they used the statistics of states in which marijuana is still illegal.
While correlation does not equal causation, decreased suicide rates in men aged 20-29 by 10.9 percent, and 9.4 percent for men aged 30-39 are nothing to scoff at. Opponents will point to studies showing higher rates of depression and psychosis among marijuana users, but it is generally accepted that the most likely explanation for that is illness causing people to self-medicate rather than the other way around.
One of the greatest dangers prohibitionists pose to society is that they seem to always blame marijuana for something it actually helps with.
Take the slanderous article posted on WebMD about the dangers of driving on marijuana, for example. They say that the rate of detecting marijuana in traffic fatality victims rose from 4% in 1999 to 12% in 2010. What they fail to mention is that overall fatalities have been steadily dropping. In 1999 the total fatalities in the U.S. were 37,140 while in 2010 that number dropped to 30,296. In 2012 our total fatalities dropped to 29,757, the first time below 30,000, all while marijuana use continues to increase.
Contrast that to another study, one that took more into account than just fatality totals and toxicology reports. and we have a completely different picture. The conclusion Dr. Daniel I. Rees came to after using the same FARS data is that traffic fatalities fall by 8–11 percent the first full year after legalization in states with medical marijuana laws. States without medical marijuana laws didn't see this drop in traffic fatalities, furthering the association with legalization.
Why does legalizing medical marijuana reduce traffic fatalities? Alcohol consumption appears to play a key role. The legalization of medical marijuana is associated with a 7.2 percent decrease in traffic fatalities in which there was no reported alcohol involvement, but this estimate is not statistically significant at conventional levels. In comparison, the legalization of medical marijuana is associated with a 13.2 percent decrease in fatalities in which at least one driver involved had a positive BAC level.
This is explained by a drop in alcohol consumption rates in medical marijuana states. Where marijuana is legally available, more people are choosing to use it as a safer alternative to alcohol for relaxing after work or on the weekends. From a public health perspective, this is also a positive effect of legalization. Even President Obama has publicly admitted that marijuana is safer than alcohol. While the study stops short of claiming that it's safer to drive under the influence of marijuana than it is for alcohol, they do acknowledge the possibility.
Like the suicide study, it may not prove the pro-marijuana stance, but it does a great deal to discredit the opposite stance. One of the biggest trends we have seen coming out of the current legalization efforts is medical studies disproving old Drug War propaganda. Let's keep the momentum going.