The American Legion has called on Congress to remove marijuana from the list of drugs that are classified as having no potential medical use.

The Legion, the country's largest veterans organization with 2.4 million members, passed a resolution at its annual convention last week to promote research on marijuana's potential use for treating post-traumatic stress disorder and traumatic brain injury.

The resolution noted that with thousands of veterans from Iraq and Afghanistan diagnosed with PTSD or TBI, and the Drug Enforcement Agency's recent approval of a study on the effectiveness of cannabis for PTSD, Congress should remove marijuana from its Schedule I designation, where it shares space with heroin, Ecstasy, LSD, Quaaludes and peyote.

"Amend legislation to remove marijuana from Schedule I and reclassify it in a category that, at a minimum, will recognize cannabis as a drug with potential medical value," the Legion wrote in its resolution, first reported by marijuana.com.

The Drug Enforcement Agency in April approved the first randomized, controlled research in the U.S. that will use inhaled marijuana to treat PTSD.

During the convention, Dr. Sue Sisley, a lead researcher on that project and a former Veterans Affairs psychiatrist, described veterans as "exhausted and [feeling] like guinea pigs" when it comes to treatment for PTSD.

"They're getting desperate. I could never reach that level of relief with traditional medications, so I knew I had to keep going," she said of her efforts to pursue cannabis research for mental health conditions.

The DEA last month elected to leave marijuana on the list of Schedule I drugs. But it also ended its monopoly on growing marijuana for medical research, a move seen by advocates as a loosening of restrictions that could pave the way for more research on cannabis.

Legion leaders said their resolution was an effort for the organization to "step forward and help veterans who are suffering from PTSD."

"There are a lot of tools that are not being utilized. Big pharma does not want them used," former American Legion National Commander Bill Detweiler said.

Sisley called the organization's decision to support marijuana research a "bold statement for a conservative veterans group."

"It's a big breakthrough. While I can't say definitively that medical marijuana works for PTSD -- we are three years away from published data -- we owe it to veterans to study this plant," Sisley said.

Earlier this year, the House passed an amendment to a Veterans Affairs funding bill that would have allowed veterans to discuss medical marijuana with their VA doctors and VA doctors to fill out the required paperwork in states where medical marijuana is legal.

The Senate Appropriations Committee also approved a similar measure.

But during negotiations on the final version the fiscal 2017 Military Construction and Veterans Affairs appropriations bill, the provision was stripped from the legislation.

The bill has stalled in the Senate over an unrelated Zika funding provision. If the medical marijuana provision is not returned to the legislation or fails to pass as a stand-alone bill, veterans wanting to use medical marijuana must continue to go through a private doctor for a recommendation.