Advocates of treating marijuana more like alcohol gained another ally recently: the United Nations.

The U.N. would claim otherwise. In fact, the U.N.'s International Narcotics Control Board would hotly deny it. The agency's latest report laments the legalization of pot in Colorado and Washington, declaring the approval of recreational marijuana use "in contravention to" the 1961 U.N. Convention on Narcotics.

Raymond Yans, the head of the INCB, has gone further—arguing that ballot measures legalizing recreational, and even medical, marijuana "undermine the humanitarian aims of the drug control system and are a threat to public health and well-being." Echoing America's domestic drug warriors, Yans called medical marijuana "a back door to legalization for recreational use."

Here in the U.S., United Nations disapproval can only help the cause of legalization where it needs help the most: on the right. According to a December poll by Gallup, Democrats favor legalization 61-38. Independents are about evenly split. But Republicans favor continued prohibition, by a 2-1 margin.

They might favor it less if they knew the U.N. were, implicitly, telling states what to do. Just look at the conservative reaction to Agenda 21—a voluntary U.N. program that encourages bike paths and urban planning. Conservatives see it as nothing less than the first step on the road to serfdom.

Take Scott Lingamfelter, who is running for the GOP nomination for lieutenant governor in Virginia. This year he sponsored a resolution denouncing Agenda 21 as a "radical" plan for "social engineering" that was being "covertly introduced" across the nation. In a January memo to constituents, he wrote that Agenda 21 is a conspiracy to "consolidate liberal power over the rest of us" and then "tear down private property ownership, single-family homes, and other basic tenets of American life."

The national GOP shares such sentiments. Its 2012 platform declared, "We strongly reject Agenda 21 as erosive of American sovereignty." It also devoted an entire segment to federalism. Republicans do not like ostensibly higher authorities mucking about in local matters, and that includes federal authorities. So it may be worth notice that the Gallup poll also showed a lopsided majority of Americans—64 percent—think Washington should not step in to enforce federal marijuana laws in states where pot has been legalized.

That may be one reason the Obama administration continues to hem and haw about its plans for Colorado and Washington. During a Senate appearance last week, Attorney General Eric Holder said—again—the administration was "still considering" its options. This hasn't pleased the nation's drug-war hawks, who want the Obama administration to file suit, pronto, to pre-empt the legalization measures.

Federal law trumps state law, and federal law defines marijuana as a Schedule I controlled substance—in the same category as heroin. This probably seems jarring to the 42 percent of Americans who have used marijuana at least once. Marijuana is not good for you, but it is not on the same plane as smack.

The consequences of marijuana prohibition, however, have grown high indeed. Marijuana accounts for nearly half of all drug prosecutions. Even if you assume half of those cases are plea-bargained down from trafficking, the country is still spending tremendous resources to punish people for having an occasional toke.

If Holder does move against Colorado and Washington, it will be interesting to see the response from another attorney general—Virginia's Ken Cuccinelli. On Thursday the Tea Party hero and champion of states' rights will give the opening speech at the annual Conservative Political Action Conference. This year CPAC organizers shut out Republican governors Bob McDonnell and Chris Christie, who evidently committed the sin of ideological deviationism. But the organizers apparently did not mind Cuccinelli telling a class at the University of Virginia he has no objection to state-level experiments with legalization—or that his own views on the issue are evolving.

In his new book The Last Line of Defense, Cuccinelli contends the states provide protection from federal tyranny. This is an argument many conservatives find as appealing as they find the U.N. objectionable. And if they extend that line of thinking just a bit, they may come around on pot.

The syllogism is easy enough to follow: The U.N. should not tell Washington what it can do, and Washington should not tell the states what they can do—so why then should the states tell individuals what they can smoke? What sovereignty is more important than the individual kind?

With liberals such as New York Mayor Michael Bloomberg dictating how much soda you can buy, Tea Party enthusiasts already are primed to declare not just "Don't tread on me" but also, "Keep your laws off my body." After all, as Lingamfelter put it in his January memo about Agenda 21: The great threat from the U.N. is that it wants to "tak[e] away individual freedoms from people like you and me." And that would be, pardon the term, a real drag.

This article originally appeared at the Richmond Times-Dispatch.