The marijuana industry had a good day in Washington Thursday, as the House Financial Services Committee passed a bill to liberalize banking laws covering the industry. This win for pot came after a pretty tough blow: A new study published in the Lancet, a highly respected medical journal, found that high-potency marijuana can make you psychotic. In fact, about half of all cases of psychoses in Amsterdam could be prevented “if high-potency cannabis were no longer available,” the data suggest.

The study doesn’t prove causality, but it certainly suggests it may be there. It illustrates the need for more research into the careless and unscientific claims that marijuana use is harmless. It also cries out for U.S. policymakers to put the brakes on the push to legalize recreational marijuana use and weaken guardrails around “medical” marijuana.