The Senate Appropriations Committee on Thursday passed an amendment that would let Veterans Affairs doctors discuss and recommend marijuana as a potential medical treatment in states where it is legal.

An addition to the fiscal 2017 Military Construction, Veterans Affairs and Related Agencies appropriations bill, the bipartisan amendment sponsored by Sen. Steve Daines, R-Montana, and Sen. Jeff Merkley, D-Oregon, would let VA doctors discuss marijuana as a potential medical treatment, similar to the allowances given civilian physicians in medical marijuana states.

The move marks the second time senators have tried to improve access to medical marijuana for veterans who are treated at VA medical facilities and want to use marijuana for medical purposes.

The provision was approved by the full Senate last November in the fiscal 2016 VA appropriations bill but was stripped from the final law.

Under the amendment, VA would be prohibited from using funds to "interfere with the ability of veterans to participate in medicinal marijuana programs approved by states or deny services to such veterans."

In January, 21 lawmakers wrote VA Secretary Bob McDonald urging him to allow doctors to discuss and recommend marijuana. The group, including 19 Democrats and two Republicans, wanted VA to abandon a policy that prohibits physicians from discussing the drug, which is still illegal under federal law.

Twenty-three states and the District of Columbia have legalized medical marijuana, and 17 states have laws allowing physicians to prescribe oils derived from marijuana plants.

Daines emphasized that the amendment would not change any laws preventing the possession or dispensing of marijuana on VA property.

It was adopted by the committee in a 20-10 vote.

The VA recommends that its physicians use "evidence-based" practices — therapies proved by scientific research to be effective — to treat mental and physical health conditions such as post-traumatic stress disorder, depression and pain.

There has been no research in the U.S. on the effectiveness of medical marijuana for relieving symptoms of post-traumatic stress disorder or other conditions, although some veterans groups and marijuana legalization advocates say it does help relieve symptoms of combat-related PTSD and anxiety.

Patricia Kime covers military and veterans' health care and medicine for Military Times. She can be reached at pkime@militarytimes.com