Marijuana has now been legalized for medical use in many states — only Idaho, Kansas, Nebraska and South Dakota still prohibit use in any form. Nine states allow recreational marijuana use, and 13 others have decriminalized recreational use to some extent. Meanwhile, public support for legalizing the drug continues to grow, and is now firmly in majority territory:
Unsurprisingly, weed has become big business — sales in Colorado alone now top $1 billion a year. A study by data analytics firm New Frontier Data recently estimated that if marijuana legalization went national, it could generate more than $10 billion in tax revenue a year.
There's just one problem: Cannabis is still illegal under federal law. During the administration of President Barack Obama, an uneasy detente existed, where the federal government agreed not to prosecute marijuana production, sale and use in states where it was legal. That effectively left things up to the states, but left open the possibility that the federal government might reverse itself and crack down. This year, the crackdown came. Attorney General Jeff Sessions announced that he was rescinding the Obama-era policy of tolerance, and that marijuana users and growers in every state in the union now had to fear arrest and prosecution by the feds.
But Sessions may find himself increasingly isolated, even within his own party. It's not just that public opinion has shifted. Unlike in past federal crackdowns, cannabis is now an incumbent industry that fills state coffers and can lobby legislators. Colorado U.S. Sen. Cory Gardner, a Republican, had threatened to block Justice Department nominees unless Sessions backed off. President Donald Trump appeared to concede, assuring the senator there would be no punishment for Colorado. Meanwhile, the Republican-controlled U.S. Senate is pushing through a bill to legalize hemp, a non-intoxicating variant of marijuana.
This is good news. Business and monetary interests may succeed where civil liberties arguments failed, bringing an end to the U.S.'s marijuana prohibition. And not a moment too soon.
For decades, marijuana opponents argued that it functioned as a gateway drug — that users would eventually get bored and be tempted to move onto stronger substances. This argument persisted for a long time, since it's hard to verify or disprove without actually getting people to regularly use marijuana (something no university ethics board would approve). Even if you happen to find a correlation between marijuana use and the abuse of drugs such as heroin and methamphetamine, that doesn't tell you much; it could easily just be that the people most likely to go on to hard drugs tend to start with cheaper, more plentiful ones like marijuana.
But the legalization of marijuana presents a natural experiment that allows us to test the gateway-drug argument. If anything, it looks like the opposite is true. In states that legalized marijuana for medicinal or recreational purposes, opioid prescriptions fell substantially. Opioid overdoses fell too. In Colorado, marijuana legalization was followed by a drop in teen abuse of heroin. Opiate overdoses, which had been climbing steadily in Colorado, suddenly began to fall after cannabis became legal.
Instead of a gateway drug, marijuana looks like it's a substitute for more addictive, more toxic substances. At a time when the U.S. is suffering a devastating epidemic of opioid and heroin abuse, marijuana's use as a substitute for these harder drugs is much needed.
Another fear was that legal marijuana would lead to an increase in criminality. But a team of economists found liberalization of state marijuana laws led to no increase in youth criminal behavior.
A second paper, by economists James Conklin, Moussa Diop and Herman Li, used a very interesting method to evaluate one aspect of legal weed's impact — they looked at house prices. When recreational cannabis was legalized, many medical marijuana dispensaries converted to retail marijuana stores. Conklin et al. found that near these stores, housing prices almost immediately rose by about 8 percent relative to houses in other areas.
If legal marijuana brought crime and bad behavior, we would have expected to see a drop in housing prices close to where the drug is sold. That's exactly what does happen with prostitution — a brothel in the Netherlands lowers the surrounding home values, presumably by making an area dangerous and disreputable. Because marijuana does the opposite suggests it probably has an enduring future as a respectable, wealth-creating business activity.
So Republicans are doing the right thing by moving to strengthen protections for legal marijuana. Sessions remains a regrettable holdout, but hopefully Trump will accede to the tide of history and rein in his regressive attorney general. Repealing the federal law against marijuana use, and leaving legalization entirely up to the states, is the logical next step.
Noah Smith is a Bloomberg View columnist. He was an assistant professor of finance at Stony Brook University, and he blogs at Noahpinion. This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.