The Drug Enforcement Administration heads the nation’s drug war. As part of that, it’s done a lot to push messaging that marijuana is dangerous — at times struggling to admit that pot isn’t as dangerous as heroin.

On Tuesday, the DEA’s Twitter account put out a chart making the case for why this kind of messaging is, in its view, necessary:

CHALLENGE: Over the long term its proven that the perception of drug harm is correlated w/use, a trend that's going in the wrong direction pic.twitter.com/2IJJHS5rCR — DEA HQ (@DEAHQ) January 9, 2017

In the DEA’s interpretation, this chart shows there a correlation between perceptions of risk and a drug’s use. Sure enough, the chart largely exemplifies that: As the perceived risk of tobacco rose, its use among 12th graders declined. And there’s a similar, although not quite as clean, story with pot, with marijuana use among 12th graders going up and remaining relatively flat as risk perceptions have dropped.

But there’s another reading of this chart that the DEA in particular won’t like — one that argues against the DEA’s work in prohibiting marijuana and cracking down on its use.

Tobacco, after all, has been legal for the entirety of the DEA’s chart. Yet all this time, the perception of how risky it is has gone up and its use has declined. That’s because of various policies, including education campaigns, mandatory warning labels, public and workplace smoking bans, and higher taxes on tobacco products.

Marijuana, meanwhile, has remained illegal on the federal level. Yet, as the DEA’s chart shows, its use has continued fluctuating and perceived risk has continued dropping despite the hundreds of thousands of arrests each year for pot possession.

While some states have legalized marijuana for medical or recreational purposes, so far there doesn’t seem to be a clean connection between legalization and use by teens: Surveys in Colorado, one of the two states to first legalize, found that reported teen pot use hasn’t gone up, while a recent study in Washington state, the other state to first legalize, found teen pot use did go up. (Some drug policy experts say, however, that it’s simply too early to gauge the effects of legalization on levels of pot use, and we should wait until a big marijuana market that widely commercializes and advertises the drug forms.)

So based on the DEA’s chart, the legal model sure seems to be working better: The legal drug (tobacco) has seen reduced use and the illegal one (marijuana) has not.

For legalization advocates, this has led to several questions: Why are hundreds of thousands arrested, gaining a potentially life- and job-ruining mark on their criminal record, in this grand effort? Why not borrow a page from the tobacco model, which uses solely public health tools to depress the use of an addictive, dangerous drug, instead of wasting money and lives on prisons and police?

President Barack Obama, for his part, has embraced the tobacco approach. He recently told Rolling Stone, “I do believe that treating [substance abuse] as a public-health issue, the same way we do with cigarettes or alcohol, is the much smarter way to deal with it.”

Legalization can go wrong if it’s not done in a strictly regulated way. Just look at how alcohol-induced deaths have steadily increased for years — or how the worst US drug epidemic ever is rooted in a drug legally prescribed by doctors.

But the DEA’s chart, at least, suggests the president and drug policy reformers may be on to something.

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