"The war on drugs has failed," declared the editors of National Review in 1996, back when the nation's foremost conservative periodical promoted ideas more intellectually rigorous than cheerleading for the Republican Party. "It is diverting intelligent energy away from how to deal with the problem of addiction. . . .It is wasting our resources, and . . . it is encouraging civil, judicial, and penal procedures associated with police states. We [here at NR] all agree on movement toward legalization, even though we may differ on just how far."

In the decade and a half since then, the federal government has shelled out more than $100 billion—vastly more, by some estimates—fighting the scourge of illegal drugs. How's that workin' out? Not too good! Last Thursday the Global Commission on Drug Policy, an international panel that included such sober souls as former Fed chairman Paul Volcker, said the U.S.-led war on drugs "has failed."

It has not simply failed. It has failed miserably. Increasing federal expenditures have risen hand-in-hand with increasing drug use. From 2002 to 2009, national drug-control funding rose from $10.8 billion a year to $15 billion—a 39 percent increase. Yet as The Chicago Tribune's Steve Chapman noted last October, roughly 22 million Americans used illegal drugs in 2009. That represents a 9 percent increase over the year before and the highest rate since 2002.

People recovering from drug and alcohol addiction are fond of defining insanity as trying the same thing over and over again and expecting a different result. By that standard, American policy toward mind-altering substances looks awfully familiar. The nation tried Prohibition once, with alcohol. Result: abject failure, rampant organized crime, and little lasting effect on consumption or addiction. In fact, Prohibition actually encouraged the use of harder spirits, since bootleggers could smuggle more alcohol in a car full of liquor than a car full of beer.

Alcohol prohibition lasted only a few years. The war on drugs has lasted for decades, and for the most part has consisted of only one solution, over and over: criminalization and imprisonment. Nearly 2 million people are arrested each year for drug offenses and a half-million are currently serving time on drug charges. Yet when stiffer sentences fail to produce the desired results, drug prohibitionists insist the penalties just aren't harsh enough. They resemble the carpenter who complained that he had cut a board three times and it was still too short.

Trying to solve the problem of addiction through incarceration is like trying to get rid of a cockroach infestation by turning on the lights. The temporary solution doesn't address the underlying problem, which requires treatment. Sometimes locking a user up doesn't even interrupt his using. Do a Google search on smuggling drugs into prison for an education on that front. If prohibition can't keep narcotics out of prison cells, it won't keep them out of playgrounds and office parks.

Decriminalization and treatment—the approach suggested by the international panel—differs from outright legalization, which is often portrayed as heartless indifference to the ravages that addiction can inflict. It is not that, or at least not only that. The moral case for legalization stems from a reverence for individual autonomy—the notion that each of us owns his own body, and none of us has the right to tell another what to do with it. Family and friends might plead with someone to change his ways, but the government has no moral authority to make him.

Conservatives, who generally abhor government paternalism and consider freedom an unalloyed good, do not look nimble when they clumsily pirouette from denouncing ObamaCare and the food police to embracing life sentences for pot smokers.

Taken to its logical extreme, the autonomy argument can support not only legalizing drugs but also legalizing prostitution, selling your organs, and abolishing the minimum wage. On the other hand, taken to its logical extreme the moral assumption embedded in drug prohibition also leads to unpopular conclusions. If the government can stop you from using meth because it harms your health and reduces your usefulness to the community, then by the same token it can stop you from other unhealthful behavior for the same reason. Already, Arizona is proposing a $50 surcharge on Medicaid recipients who smoke or weigh too much. Maricopa County is charging smokers $450 more for health insurance—and taking a swab to test for nicotine. How long before the common-good rationale justifies mandatory exercise for everyone?

We don't have to chase every one of those philosophical digressions down a rabbit hole to recognize the obvious: America is spending tens of billions of dollars a year putting drug users and sellers in prison, without putting much of a dent in drug consumption. The drug war has failed, and its advocates' best thinking got us here. Isn't it time they tried something else?

A. Barton Hinkle is a columnist at the Richmond Times-Dispatch. This article originally appeared at the Richmond Times-Dispatch.