Democratic presidential candidate Hillary Clinton doesn’t have a firm stance on marijuana legalization yet — she wants to see more research first. But there are some challenges to getting that research, she said.

At an ABC town hall April 21, Clinton told audience member Evan Nison, a National Organization for the Reform of Marijuana Laws board member, what she would do as president to address the marijuana legalization debate.

"I've said I want to move marijuana off of Schedule I, which you understand means that you can't do any research about it," she said. "You can't do anything, and I think that's wrong. We have enough anecdotal evidence, as you well know being a member of the NORML Board, about what marijuana can do for medical conditions, easing pain. And we need to be doing research on it because I am 100 percent in favor of medical uses for marijuana. But I want to know what the evidence is."

The 1970 Controlled Substances Act classified marijuana as a Schedule I drug, a category that includes drugs with a high potential for abuse and no accepted medical use. This puts marijuana in the same class as heroin and ecstasy and a notch higher than meth and cocaine.

We wondered if Clinton was correct that marijuana’s Schedule I classification means scientists can’t research it. (Hat-tip to our buds at FactCheck.org who looked at her claim first.)

We talked to some scientists who do, in fact, research marijuana. The regulatory hoops make their work challenging but not impossible.

Stuck in the weeds

The government doesn’t ban scientific research on Schedule I drugs like marijuana. In 2015, the National Institutes of Health put approximately $111 million into 281 research projects studying cannabinoids, which are chemical compounds found in marijuana. (Not all of these studies actually involve giving marijuana to human subjects.)

But the government has tried to make it harder to study marijuana and other drugs it has historically considered dangerous and without medical use, for fear that the drugs could be stolen or fall into the wrong hands, said John Hudak, a senior fellow at the Brookings Institution and an expert in federal marijuana policy.

"Marijuana has always been treated most unique among scheduled drugs in ways that made it even harder to study," especially in terms of acquiring plants for the research, Hudak told PolitiFact.

As a result, in many states where medical marijuana is legal, doctors and policymakers have to base their practices on limited science, Hudak and co-author Grace Wallack wrote in a Brookings report. He cited research that found Schedule I designations discourage scientists from trying to study these drugs.

To conduct marijuana research, researchers have to submit an investigational new drug application to the Food and Drug Administration, and the Drug Enforcement Administration has to license the research site and the investigating scientist.

If a scientist wanted to conduct three studies on a non-Schedule I drug in three different labs, he or she could get an umbrella approval for this project. But to conduct a similar set of studies on a Schedule I drug such as marijuana, the researcher would have to get approval for each individual site and investigator, said Igor Grant, director of the Center for Medical Cannabis Research at the University of California, San Diego.

Until about a year ago, a Public Health Service committee also had to review privately funded projects, in a process almost identical to the FDA review. But President Barack Obama’s administration did away with that requirement.

Grant, whose lab has completed seven studies on medical uses for cannabis, said that before this revision, it could take between six and 18 months to get all the necessary government approvals to start a study. Now, it takes a little less time.

The supply of federally approved marijuana plants is another major barrier. If researchers want to use the marijuana plant, there is only one source: the University of Mississippi, which contracts with the National Institute of Drug Abuse to grow marijuana for research purposes. So researchers can only get however much marijuana the facility is able to produce, and they’re subject to the facility’s timeline.

The program has good intentions in providing drugs that might otherwise be difficult to work with, and they can control the chemical makeup of the plant, said Christine Rabinak, a pharmacy and neuroscience professor at Wayne State University. But there are some concerns about how well the government’s supply matches the kind of marijuana that is currently commercially available for medicinal purposes.

"I think we are going to be limited on what research can be conducted in the United States with other strains of cannabis because of these federal barriers," she said.

Some researchers, including Rabinak, use synthetic versions of chemical compounds found in marijuana, which she said are much easier to acquire than the plant itself.

Grant said that if the government were to reschedule marijuana to a lower classification, there would likely be more marijuana research because the project review process would be so much easier. It would especially open up opportunities for scientists who might not have the time or resources to spend months waiting for federal approval under the current rules.

Hudak’s Brookings paper concluded that rescheduling marijuana would remove one hurdle for researchers, while also recommending lifting the federal government’s control over growing marijuana plants for research and reforming licensing requirements, among other policy changes.

While Clinton’ statement is incorrect, there’s some truth to her larger point that current policy makes it hard to research marijuana, Grant said.

"It does not mean the studies cannot be done or that the federal government is consciously trying to block the studies," he said. "It’s just a complicated process."

Our ruling

Clinton said marijuana is a Schedule I drug, "which you understand means that you can’t do any research about it."

It’s hard to research marijuana, especially using plants (as opposed to synthetic versions) in studies involving human subjects. There are many regulatory hoops scientists have to navigate, and the government has a single-source monopoly on marijuana plants to be used for research. All of this makes setting up a marijuana experiment a lengthy and daunting process.

However, there are scientists currently studying marijuana, and federal funding supports some of these experiments. Clinton’s statement gives the impression that the government bans marijuana research flat-out, and that’s not the case.

Her statement contains an element of truth but ignores critical facts that would give a different impression, so we rate it Mostly False.