Legalizing cannabis increases use and addiction, unless it is tightly controlled, says research

Removing criminal penalties for possessing cannabis for personal use, or introducing tightly controlled legalization of cannabis, does not appear to increase levels of cannabis use. However, the commercial sale of cannabis is linked to increased health risks, with large-scale for-profit markets—such as those seen in the U.S. and Canada—resulting in more potent products and higher rates of addiction.