On Sunday, the conference championship games will be played in each of the two states where it’s now legal to smoke marijuana for recreational purposes. And while the NFL remains steadfastly opposed to players smoking for any purpose, the league’s position eventually could be mellowing.

In an extensive look at marijuana use in the NFL, Andrea Kremer of HBO’s Real Sports with Bryant Gumbel asks senior V.P. of labor law and policy Adolpho Birch whether a player who believes marijuana helps him with pain management and recovery should smoke it.

“He should not use marijuana,” Birch tells Kremer in an advance copy of the broadcast, which debuts on Tuesday, January 21, at 10:00 p.m. ET. “[H]e should consult his team physician or primary physician. If pain management is an issue for him, they can provide him with assistance in that respect.”

But what about the players who don’t want to use prescription medication, given the potential for addiction and side effects?

“I wouldn’t know . . . how to respond to them other than to say that the NFL and the NFL Players Association have made a determination that marijuana is not a substance for which the exemptions for that type of use would be permitted,” Birch says.

Plenty of players don’t care. Former Broncos tight end Nate Jackson, who smoked marijuana while playing for pain-management purposes, estimates that “maybe half” of the league’s players use marijuana. (Former NFL tackle Lomas Brown previously has pegged marijuana use by the league’s players at 50 percent.)

“For me personally, very viable,” Jackson tells Kremer regarding the benefits of marijuana. “I prefer it. Marijuana was something that helped me, as the season wore on, my body would start to break down. I was in a lot of pain.”

It’s possible that marijuana can heal not only bodies but also brains. Research conducted by Dr. Raphael Machoulam, described as the world’s leading expert on marijuana, has discovered the healing of brain tissue in mice given a marijuana compound. Dr. Machoulam believes those benefits could translate to humans, too.

If that can be proven, the NFL could change its tune.

“I think we can engage in a lot of what if’s,” Birch said. “That certainly is an intriguing one to hear. Clearly, there is not something that is able to be put before us today to make it a decision that needs to be reviewed today. . . . We’ll look at anything that we think is helpful to players, consistent with our values, and able to be worked on within the context of our policy, certainly.”

But the policy hasn’t been engraved on stone tablets by the hand of God. The policy can be changed. And as more states where NFL teams play legalize marijuana, the league’s policy looks outdated — especially since it only prohibits the “illegal use” of marijuana.

Initially, the NFL shrugged at marijuana becoming legal in Colorado and Washington because it remained a controlled substance (and thus illegal) under federal law. But as the substance gains more acceptance by the various states of the Union and in mainstream society, and as the potential benefits of the substance become better understood, the NFL’s ongoing desire to regulate player behavior away from the field that has no impact on performance eventually will look foolish.

If it doesn’t already.