On marijuana, politicians are catching up with public opinion, and the federal government is catching up with the states. Fifteen states plus the District of Columbia have made recreational use legal. Most states have made it legal for medical (and “medical”) reasons. Polls show majority support for that policy.

Now the U.S. House has voted, for the first time, to end the federal prohibition, decriminalizing the drug and vacating nonviolent marijuana-related convictions. But the cause has not yet triumphed. Most Republicans still favor prohibition, and so does President-elect Joe Biden. The bill won’t pass the Senate or become law.

In an ideal world, each side of this debate would rethink its position in light of what the other side gets right. What the pro-pot legislators understand is that federal prohibition is unsustainable. But Biden and the Republicans have reasonable worries about the risks of applying a laissez-faire approach to marijuana.

Government bans on any product ask law enforcement to come between willing buyers and willing sellers. This always has the potential to result in unjustly selective enforcement and to breed disrespect for the law.

Now federalism is making enforcement even less tenable. The federal government has always relied on states and localities to do the heavy lifting of enforcing bans on illicit drugs. It has neither the will nor the resources to enforce federal law absent local cooperation.

We are left with the worst of both worlds: a half-hearted war on pot that wastes law-enforcement resources and puts an unlucky few in state prison while leaving a large illegal market in place.

A purer federalist answer to marijuana policy, where each state goes its own way and the federal government confines itself to blocking interstate traffic, has theoretical appeal. In practice, though, states are unlikely to be able to maintain drug prohibitions if their neighbors have abandoned the fight. Even discouraging marijuana use through steep taxes will probably prove beyond a state’s capacity because of smuggling. (Nearly half the cigarettes smoked in New York and California come from out of state because of state taxes.)

The chief drawback of opting for full legalization is that the number of problem users will increase. While most people who use marijuana do so occasionally, habitual users account for roughly 80 percent of consumption. It won’t kill them the way alcohol can. But for many of them, it will interfere with other activities and elude their control.

Mark Kleiman, a scholar of drug policy, explained why a free market in pot would target these problem users and minors: “From the viewpoint of a cannabis company, people struggling with cannabis use disorder don’t present a problem; they are a target demographic. And use by minors – a nightmare for parents and teachers – is the dream of a cannabis marketer, because the earlier someone starts the more likely that person is to become a heavy user.”

Kleiman, who died in 2019, didn’t conclude that marijuana should, therefore, continue to be prohibited. Instead, he argued that possession and use should be legal – but that sales should be confined to nonprofits, user cooperatives and state monopolies.

This policy would avoid most of the costs of prohibition. But it wouldn’t give providers a financial incentive to expand their customer base. It would be compatible with a national tax that raised the price in a way that barely inconvenienced most users while discouraging overindulgence. And it would inhibit the formation of a powerful lobby with an interest in fighting such a tax, and in stopping other policies to promote public health.

In the case of marijuana, the efficiency and productivity of free-market capitalism would be likely to create more harm than good. We should, therefore, restrain its operation. While federal prohibition should end, we can and should tolerate use without being wholly indifferent to it. To paraphrase Kleiman, we ought to find a way to stop making marijuana a felony without making it an industry.