Medical marijuana might be legal in 29 states, but NBA players still aren’t allowed to use it, even to treat injuries. But that might change soon.

The head of the National Basketball Players Association (NBPA), the union which represents players, said she’s supportive of marijuana use, even though it’s banned in the NBA.

“My own view is that there are substantial signs that support its efficacy and the value that it has for us, especially pain management,” the union's executive director Michele Roberts told SB Nation on Monday. “We’re in talks with the league to see where we can go with it.”

Roberts isn’t alone. Current and former players have advocated for marijuana use in the past, and they picked up an influential ally in October, when former NBA commissioner David Stern came out in support of pot in the league.

"I'm now at the point where personally I think it should be removed from the banned list," Stern told former NBA player and weed entrepreneur Al Harrington in a documentary. "You've persuaded me."

Under the NBA’s current rules, weed use is banned alongside hard drugs like LSD and meth, and players can be fined, suspended, and put into drug treatment if they test positive for pot. The league and the player’s union work jointly to administer the program, so both parties would have to hammer out any rule changes.

NBA commissioner Adam Silver said in August the issue needed further study, but if the science checked out, he was open to treating weed like any other medicine. The NBA did not respond to a request for comment.

But Roberts is worried that even if the NBA gets onboard, Attorney General Jeff Sessions could crack down on her players for something that’s legal in more than half of the country. Sessions rescinded an Obama-era rule in January shielding individuals and businesses in states with legal pot from certain forms of prosecution.

“If we do go down that road, we have to protect our players from — my words — a crazed attorney general who says he will prosecute violations of the law involving marijuana and he doesn’t care what individual states say,” Roberts added.

Getting behind cannabis use is not unheard of in professional sports. The NFL told players and their representatives last July that it’s open to researching medical marijuana, which former players have suggested as a substitute for opioids in treating serious pain issues and Chronic Traumatic Encephalopathy, a degenerative brain disease often found in football players.