John Minchillo / AP

During a discussion about solutions to the opioid crisis during last night’s Democratic primary debate, Beto O’Rourke suggested that when pharmaceutical companies go low, we should get high.

The former congressman from El Paso said a veteran he once met wouldn’t have gotten addicted to heroin if the veteran had been prescribed marijuana instead of opioids for his health condition. “Now imagine that veteran, instead of being prescribed an opioid, had been prescribed marijuana, because we made that legal in America [and] ensured the VA could prescribe it,” O’Rourke said.

This was a savvy answer. It clearly won O’Rourke some fans: At the mention of weed, the entrepreneur Andrew Yang, another Democratic presidential candidate, yelled across the stage, “PREACH, Beto.” (And thereby perhaps underscored O’Rourke’s famed youth-pastor energy.) O’Rourke was also in line with the majority of American voters—two-thirds of whom also support legalizing marijuana—as well as the majority of Democratic candidates for president. Joe Biden, the former vice president, whose stance on marijuana is the most conservative of the bunch, has called merely for decriminalizing the substance.

Putting forth marijuana as a solution for chronic pain stands to differentiate O’Rourke, whose campaign has been flagging in recent months. The other candidates mostly focused on putting pharmaceutical executives who have peddled opioids in jail. That’s all well and just, Beto seemed to say, but marijuana could help replace those awful opioids we’re trying to get rid of.

Except, it’s not really clear that it can. As I wrote in June, while it’s true that the introduction of medical-marijuana laws was initially associated with a decline in opioid-overdose deaths, that relationship hasn’t held up in recent years. When the data include states that introduced medical-marijuana laws between 2010 and 2017, medical marijuana was associated with a 23 percent increase in overdose deaths, instead of a reduction in opioid overdoses.

This doesn’t mean that marijuana has no role in pain management; other studies have shown it can indeed reduce pain. And there are certainly reasons to decriminalize marijuana other than to halt the spread of opioids, such as to reduce mass incarceration. But the evidence isn’t quite there yet that marijuana can be a perfect substitute for prescription painkillers. (And fortunately, we don’t have to wait for such evidence to reduce opioid prescribing: Legal, nonaddictive drugs exist that perform just as well as opioids for many types of pain.)

Of course, if everything that was said in a primary debate was backed by randomized controlled studies, these things would be a lot shorter than three hours. Part of the exercise is seeing how ideas play. O’Rourke shrewdly picked up on Americans’ exhaustion with the War on Drugs, their growing acceptance of marijuana, and their sense that prescription opioids are a far greater menace to Americans’ health than plain old pot. He knew he could “preach,” and that his sermon wouldn’t fall on deaf ears.

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