Does Cannabis Legalization Increase Violent Crime?

Let’s set aside the idea that legalizing marijuana will reduce violent crime: violent crime is unpredictable and this is probably too optimistic a claim to pin to any one change in the law not geared directly at crime reduction (though it’s not crazy to imagine that obviating black markets might reduce crime in certain instances). Berenson isn’t just expressing skepticism of that claim — he’s arguing, in strong language, that legalization has done the opposite. And if, in fact, there were a tight, clearly illustrated link between cannabis legalization and increases in violent crime, that would certainly be an important bit of evidence to consider as legalization continues. But Berenson doesn’t come close to showing this. Rather, this paragraph is a case study in how to misleadingly use statistics to make oversimplified arguments about human behavior and public policy.

At root, Berenson’s fishiest move is his choice of 2014 as a baseline year. “Nothing interesting happened with regard to pot in 2014,” said Mark Kleiman, a drug expert and public-policy professor at NYU who has himself urged caution over marijuana-legalization Pollyannaish-ness, in an email, “but there was a national uptick in homicide in 2015–2016.”