The Drug Enforcement Administration made headlines last week for sticking to the status quo: the agency declined to change cannabis’ classification under the Controlled Substances Act to a lower, less strictly regulated schedule.

Cannabis sits alongside heroin and LSD in the DEA’s Schedule I category, reserved for the most dangerous substances. Schedule II drugs include narcotics such as methadone and oxycodone that are medically useful but have a high potential for harm. Advocates say the existing classification of cannabis makes little sense: they cite studies that show the drug can help patients to manage pain without any serious risk of abuse. The only problem? The Food and Drug Administration has done studies of its own and its experts do not agree.

There is one way to resolve the debate: more research. Until there is substantial evidence that cannabis does more to help than to hurt, the DEA is right not to reschedule the drug. The agency took a step in the right direction by allowing more places to grow cannabis for research on how the drug could treat chronic pain and diseases such as epilepsy. But even with the rule change, most scientists who want to learn more about cannabis’ effects will find themselves hamstrung. Schedule I drugs are not supposed to have medical benefits, so the rules governing them do not easily allow for clinical trials. That means researchers and the DEA are stuck: the DEA cannot reclassify cannabis unless research proves its effectiveness, but scientists have a hard time doing research unless the DEA reclassifies cannabis.

There may be a way. In the House, representatives Andy Harris, the Republic from Maryland, and Earl Blumenauer, the Democrat from Oregon, recently introduced a Bill that would carve out a special space in the country’s drug code for cannabis. The law would make it easier for cannabis to be produced for research purposes, and researchers would have to jump through fewer hoops to get approval for their studies.

There is a reason why Harris, a longtime cannabis sceptic, and Blumenauer, one of the drug’s more ardent advocates, have teamed up on the Bill: it is a smart idea. The country is clamouring for change on cannabis. But change should be based on evidence, and scientists cannot provide evidence until they are given the tools to do their job.