With a growing number of US states legalizing marijuana use, scientists and policymakers are once again engaged in a pitched battle over the risks and benefits of THC, the primary psychoactive component of marijuana. Proponents argue that legalization offers important benefits, citing evidence that marijuana may help treat a variety of medical conditions ranging from chronic pain to epilepsy and nausea, while generating substantial revenue–as much as $60 billion according to one estimate–for state and local governments. Legalization, advocates add, also protects public health as safer, regulated sources of marijuana come online to replace black-market alternatives.

But the situation appears to be more complicated than many legalization proponents let on. Critics cite research showing that lax marijuana laws tend to significantly increase use, amplifying the drug’s harmful side effects. For example, some studies show that legalization boosts emergency room visits for psychosis and cannabis hyperemesis syndrome (CHS)—an unpleasant condition characterized by simultaneous screaming and vomiting, often called scromiting. “With the widespread use, increased potency and legalization of marijuana in multiple states in the U.S., CHS may be becoming increasingly common,” the Cleveland Clinic warns.

And while the direction of the association is uncertain (does THC cause mental health disorders or do people with those disorders gravitate toward marijuana) it’s clear the drug is linked to conditions like schizophrenia.

Although drug prohibition is usually the purview of social conservatives, former New York Times reporter Alex Berenson has emerged as perhaps the most forceful opponent of legalization in recent years, arguing in his 2020 book “Tell Your Children: The Truth About Marijuana, Mental Illness, and Violence” that cannabis is far more harmful than the public has been told.

To make sense of these competing claims, Cam and Liza speak with Reason Foundation health care policy analyst Jacob James Rich about his critique of Berenson’s work and the broader effects of drug legalization. Is it time to fully legalize marijuana, or has the public been sold a bill of goods by the drug’s defenders? Let’s take a look.

Jacob James Rich is a policy analyst at Reason Foundation, specializing in prescription and illegal drug regulations. He holds master’s degrees in mathematics and economics and is currently a Ph.D. student at Case Western Reserve School of Medicine. Follow him on X @jacobjamesrich.

Dr. Liza Dunn is a medical toxicologist and the medical affairs lead at Bayer Crop Science. Follow her on X @DrLizaMD

Cameron J. English is the director of bio-sciences at the American Council on Science and Health. Visit his website and follow him on X @camjenglish