The Conversation analyzed city-level data from states across the US and found that medical marijuana laws have little effect on violent or property crime in nearly all medical marijuana states.

In the case of California, the crime rates actually show a substantial decrease of around 20%.

The passage of medical marijuana laws offers researchers a good natural experiment to study the causal effects of marijuana use on a variety of health outcomes, including drunk driving, hard drug use and opioid painkiller use.

See the original article at The Conversation