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WASHINGTON — It’s a major shift in U.S. policy regarding medical uses for marijuana.

The federal government has given its go-ahead on a study looking at marijuana as a treatment for veterans who have post-traumatic stress disorder according to the Associated Press.

The decision from the Department of Health and Human Services caught marijuana advocates a bit off guard. They have tried for decades to get federal approval for research into pot’s medicinal uses.

The Food and Drug Administration approved the University of Arizona research proposal a long time ago.

The AP reports the HHS sent a letter last week that allows the purchase of medical marijuana by the study’s main financial backer, the Multidisciplinary Association for Psychedelic Studies. The group supports medical research and legalization of marijuana and other drugs.

It has wanted to start the research for more than 22 years.

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