As if U.S. drug policy weren’t controversial enough, consider the widening inconsistency between the federal government’s hard-line stance on marijuana and the more liberal policies being adopted by many states—an inconsistency that’s creating legal confusion and raising questions about the allocation of limited government resources for the “war on drugs.”

Case in point: last week, a U.S. appeals court ruled that marijuana should continue to be classified as a highly dangerous drug—this despite the fact that 18 states, including, as of Jan. 1, Massachusetts, have legalized its medical use.

The lawsuit, filed by the drug policy reform group Americans for Safe Access and several others, challenged a 2011 Drug Enforcement Agency decision not to reclassify marijuana. Under the 1970 Controlled Substance Act, marijuana (along with heroin and LSD, among other drugs) is designated a Schedule 1 substance, defined as a drug with a high potential for abuse and no known medical benefit and subject to the strictest level of control. (Cocaine, opium and methamphetamines are classified as Schedule 2 drugs, as they’re considered to have valid medical uses.)

But while the feds refuse to budge, Americans are increasingly demonstrating a more relaxed attitude toward marijuana, demonstrated by the wave of reforms at the state level, including laws enabling its medical use, decriminalizing possession of small amounts and, most dramatically, legalizing its recreational use, as Colorado and Washington both did in November. Those changes have led to tension between federal agencies and the states, which are left wondering if feds will interfere with their new policies.

The Americans for Safe Access case addressed a glaring Catch-22 in the fight over medical marijuana: while numerous studies suggest that the drug does, indeed, have medicinal value, the DEA rejects those studies as not meeting its standards. But researchers who want to conduct more research on the drug find themselves unable to access it legally, because of its Schedule 1 classification.

That’s the position Lyle Craker, a UMass Amherst professor of plant sciences, finds himself in. Craker has spent more than a decade fighting for permission from the DEA to study marijuana in his lab, only to be repeatedly rebuffed. Craker is neither for or against medical marijuana; rather, he’s for valid scientific research that will determine whether the plant has medical uses.

“We need to have honest clinical trials to determine whether this is a good medicine. The people deserve that,” he told the Advocate last year. “[P]robably the vast majority of scientists would say this should be investigated like anything else. If it turns out it’s bad for people, let’s really ban the material. But if it has any medical benefits, we should try to develop it into medical materials, as we do with many other plants.”

Last week’s court ruling didn’t address the issue of marijuana’s medical utility, but rather considered the question of whether the DEA’s 2011 decision was sound. The court found that the agency had valid evidence to back its decision, writing that petitioners who want to change the drug’s classification “have not pointed to ‘adequate and well-controlled studies’ confirming the efficacy of marijuana for medicinal uses.” Of course, the question remains: how can those studies be conducted, if the drug remains under such strict control by the federal government?

In a statement in response to the court’s ruling, Americans for Safe Access cofounder Don Duncan wrote, “Politics have trumped medical science on this issue,” noting that the group had cited in its case more than 200 studies demonstrating marijuana’s medical benefits. ASA says it will seek a rehearing on the matter and will take the case to the Supreme Court if necessary. The group also plans to lobby Congress next month, as part of its national conference for marijuana reform activists.

Numerous medical groups, including the Mass. Medical Society, have also called on the DEA to reclassify marijuana to allow more scientific study. The MMS opposed the 2012 ballot question that legalized medical marijuana in the commonwealth, saying there wasn’t enough credible scientific evidence showing that the drug has medicinal value. “We’re a proponent of evidence-based medicine,” MMS President Richard Aghababian told the Advocate. “We would want [anecdotal evidence] to be verified by science, by carefully documented clinical trials, as with any other drug or intervention.”

Last spring, the MMS House of Delegates passed a resolution calling for the federal reclassification of marijuana “so that its potential medicinal use by humans may be further studied and potentially regulated by the U.S. Food and Drug Administration.”•