The Drug Enforcement Administration (DEA) has maintained marijuana's classification as a harmful drug with no medical benefits despite scientific evidence to the contrary, a new report said, adding that the agency has also obstructed research that could lead to the substance's reclassification.

“The DEA impedes research by abusing its discretionary powers over the scheduling process, making it difficult to obtain marijuana for research purposes. We recommend taking away the DEA’s power over drug scheduling and access to drugs for research,” Ethan Nadelmann, executive director of the Drug Policy Alliance (DPA), said Wednesday during a teleconference.

The report, “The DEA: Four Decades of Impeding and Rejecting Science,” released by the Multidisciplinary Association for Psychedelic Studies (MAPS) and DPA, calls on the DEA to end its “unjustifiable” monopoly of the supply of research grade marijuana available for federally approved research.

The DEA has ignored calls to reschedule marijuana — which is currently called a Schedule 1 drug meaning it has no known medical value and is on par with drugs like heroin and crack.

Medical marijuana advocates are calling for a rescheduling to Schedule 2 — where the Food and Drug Administration (FDA) would regulate it as a prescription medicine, allowing easier access to medical grade cannabis for scientific research, the study said.

“The DEA has created a Catch-22 — saying that the FDA didn’t approve marijuana therefore it’s bogus, while at the same time obstructing FDA research necessary for approval,” Jag Davies, publications manager for DPA, said. He added that no other drug is treated like marijuana, which is available only from a single government source, the DEA, for research purposes.

The agency has ignored its own DEA administrative law judges, tasked with evaluating the evidence of rescheduling, who have recommended changing marijuana to a Schedule 2 substance, the report said.

“This concerns me greatly as someone who has studied marijuana and given thousands of doses of the drug. All the studies have shown potential,” Professor Carl Hart, department of psychology and psychiatry at Columbia University, said in the teleconference.

“The notion that the DEA has not thought about reconsidering scheduling of marijuana seems to be against scientific evidence and what we’re trying to do as a society that relies on empirical evidence to make decisions,” Hart added.

While the DEA continues to argue there is insufficient evidence to support rescheduling marijuana, it systematically impedes scientific research that could prove otherwise, the report said.

In 1992, DEA Administrator Robert Bonner said that marijuana had potential medical uses that should be researched, Rick Doblin, executive director of MAPS, said. Doblin took him at his word and began trying to do just that – but 20 years later, he has been unable to start a single privately funded medical marijuana drug development study.

“The main reason is the resistance of the DEA to opening the door to research despite that claim. The DEA has a monopoly on the production of marijuana that can be used in FDA research,” Doblin said. “We have to go to the agency that’s conducting research into the harms of marijuana.”

Congressman Steven Cohen (D-TN) — who voted last month in a bipartisan measure in the House to prohibit the DEA from undermining state medical marijuana laws — said the DEA has constantly opposed anything that would change their mindset on marijuana. The agency has even interfered with medical marijuana dispensaries in states that have approved the practice.

“(The DEA is) totally against marijuana, and will not admit that it’s not as harmful as heroin or crack or cocaine,” Cohen said. “The DEA should be interested in protecting the American public relating to drugs, and should allow and encourage research.”

Congressman Dana Rohrabacher (R-CA) who also voted for the House measure agreed, saying “Those people who are basically calling for a limit on any scientific endeavor are usually the ones who understand they have a weak argument… Nobody should be afraid of the truth.”

The report recommends removing the responsibility for determining drug classifications from the DEA — perhaps moving it to a non-governmental agency such as the National Academy of Sciences.

In the meantime, voters have taken the matter into their own hands with many states legalizing marijuana for medical use over past years. About half of Americans live in states that now allow the practice.

Iraq war veteran Sean Azzariti said medical marijuana saved his life. Azzariti suffered from severe post-traumatic stress disorder after serving in Iraq and was prescribed 10 to 13 pills to take every day.

“Taking this cocktail turned me into a shell of the person I am today. … I was fortunate enough to be aware of that,” said Azzarti, who is an activist for the legalization of marijuana. Since PTSD is not qualifying ailment for medical marijuana use, he got his card for chronic nausea instead.

“To say the least I’m living prof that cannabis saves lives … it may not be the answer for everyone, but not only vets, but others should have the safe, legal option to treat their ailments with marijuana instead of all the prescription pills,” Azzariti said.

In recent years, U.S. public opinion has changed very quickly about marijuana and sentencing reform with President Barack Obama and Department of Justice Attorney General Eric Holder strongly supporting an end to the so-called "war on drugs" and mass incarceration.

But the DEA is “this holdover from another era — sounding like they’re coming straight out of a ‘Just Say No’ act from the 1980s,” Davies said.

“The DEA is a police and propaganda agency,” Nadelmann said. “It makes no sense for it to be in charge of federal decisions involving scientific research and medical practice.”