According to the foremost authority on federal drug laws, Attorney General Jeff Sessions, cannabis legalization causes violence. The former senator has said, without providing data, that “Experts are telling me there’s more violence around marijuana than one would think and there’s big money involved.”

Sessions’ explanation for this violence is a somewhat nonsensical one, saying that higher THC levels in marijuana would for some reason cause an uptick in violent behavior. “… current levels of THC in marijuana are very high compared to what they were a few years ago,” he said, “and we’re seeing real violence around that.”

It’s unclear what the Attorney General means by that. Also unclear is his argument that legalization has somehow made the market more prone to violence, saying that the problem is, “You can’t sue somebody for a drug debt. The only way to get your money is through strong-arm tactics, and violence tends to follow that.”

This argument does seem to disprove his own point however. If cannabis were to be legalized at the federal level, then it would be a lot easier to sue someone over a weed debt, and that should, by his own logic, lead to a decrease in “strong-arm tactics.”

So, what is the science on violence and weed?

Contrary to Sessions’ remarks, studies have actually discovered an inverse relationship between medical marijuana legalization and violent crime. Recent findings published in the science journal Plus One show that over a ten year period, states with medical marijuana legalization showed an average decrease in homicide and assault.

In addition, the study found that “robbery and burglary rates were unaffected by medicinal marijuana legislation, which runs counter to the claim that dispensaries and grow houses lead to an increase in victimization due to the opportunity structures linked to the amount of drugs and cash that are present.”

That’s on the sociological level. On the scale of the individual, there is some indication that prolonged cannabis use can make a person more likely to commit violent acts. A long range British study of delinquents found that individuals with “continued exposure to cannabis” throughout life was “associated with a higher risk of subsequent violent behaviour,” in terms of convictions and self-reported violence.

Photo via Flickr user Dank Depot