In early August the Drug Enforcement Administration declined to reclassify marijuana under the federal Controlled Substances Act. The drug is currently listed on Schedule I, meaning that it is viewed as having “no currently accepted medical use in treatment” and is therefore technically banned by federal law. The proposed change would have moved it to Schedule II, where it would join morphine, opium and codeine. That would make marijuana potentially available by prescription nationwide. Such a change would have been good for patients and scientists, and it would have represented a big step toward resolving the hypocritical mess that characterizes current law.

Despite many people's assumptions to the contrary, the existing law does not ban scientific investigation into the harms and benefits of the drug. It's true that scientists studying marijuana must jump through multiple bureaucratic and regulatory hoops, and one of these just became a bit easier to navigate. Currently researchers who want to study the drug must get it from the University of Mississippi, which is the only university now permitted to grow marijuana plants for research purposes. When the DEA announced in August that it would not reschedule marijuana, it did say that it would let other institutions apply for permission to start growing the plants as well. That was a step in the right direction—but it's not enough.

Despite the regulatory barriers, dozens of scientists—myself included—have been engaged in research on the harms and benefits of marijuana for decades, and the evidence shows that the drug has many helpful therapeutic uses. For example, it stimulates appetite in HIV-positive patients, which could be a lifesaver for someone suffering from AIDS wasting syndrome. It is also useful in the treatment of neuropathic pain, chronic pain, and spasticity caused by multiple sclerosis.

Therapeutic benefits such as these have compelled citizens to vote repeatedly, over the past two decades, to legalize medical marijuana at the state level. Today 25 states and the District of Columbia allow patients to take the drug for specific conditions. And yet federal law still technically forbids the use of medical marijuana. The inconsistency of federal law with reality at the state level—and with the growing body of research demonstrating the benefits of the substance—makes marijuana's Schedule I status seem like medical and bureaucratic hypocrisy.

There is now a general sentiment among scientists that the failed war on drugs has biased the DEA against acknowledging any therapeutic potential for marijuana. The petition to reschedule the substance that the agency responded to this past summer was five years old. It is hard to avoid the impression that DEA leadership was stalling, hoping that the public would simply forget about the issue. Last year DEA acting administrator Chuck Rosenberg described the very concept of medical marijuana as “a joke.”

Perhaps it's also a joke that a law-enforcement agency has the final word on a medical issue.

As a scientist and educator, I am worried that our illogical, unscientific scheduling of marijuana is costing us credibility with young people and with those seeking treatments for a variety of conditions. I am further concerned that people most in need of our help and advice will reject other drug-related information from “official” sources, even when it is accurate. And when patients reject official advice and proved medicine, they become more susceptible to quackery. It's time we lessened the outsized influence of a law-enforcement agency on medical decisions and started to rebuild our credibility as scientists on the issue of marijuana.