Jerry Jones, the owner of the Dallas Cowboys said in a recent meeting of National Football League owners that the league should “drop its prohibition on marijuana use,” according to Pro Football Talk’s Mike Florio.

While recreational marijuana use is legal in eight states plus Washington, and medical marijuana is legal in about 20 more, NFL players are banned from using the drug for any purposes under the existing collective bargaining agreement, which expires in 2020. Under that agreement, players who test positive for marijuana must enter a substance abuse programme. Subsequent violations lead to fines, ten-game suspensions, and, ultimately, banishment from the league.

Former NFL players have been increasingly vocal in their criticism of the ban in recent years, saying that medical marijuana is a safe alternative to the powerful prescription opiates routinely prescribed to NFL players for pain. Documents obtained by The Post this year show that NFL teams are heavy users of prescription pain medications, averaging about “six to seven pain pills or injections a week per player over the course of a typical NFL season”.

Science, as it turns out, is on the players’ — and now Jones’s — side.

There is little evidence that opiates work for the chronic aches and pains often suffered by football players.

But there is strong evidence that anyone, NFL professional or otherwise, who uses opiates on a long-term basis is putting themselves at serious risk for drug dependency, overdose and death.

A 2014 review of 39 studies investigating the efficacy of opiate painkillers for chronic pain found that “evidence on long-term opioid therapy for chronic pain is very limited but suggests an increased risk of serious harms that appear to be dose-dependent”.

In other words, there is little evidence of benefit for treating chronic pain with opioids, but a there is a real risk of harm.

The implications of this finding should not be understated, for either NFL players or the public. Opiate painkillers, such as the ones prescribed in bulk by the NFL, kill more than 15,000 people a year via overdose. Marijuana has never killed anyone, according to the Drug Enforcement Agency.

On the other hand, chronic pain is one of the conditions that marijuana has been shown to be effective at treating. The National Academies of Sciences, Medicine and Engineering published an expansive literature review this year, spanning decades of research and showing “substantial evidence that cannabis is an effective treatment for chronic pain in adults”.

The NFL, in other words, is pumping its players full of highly addictive and deadly substances that are of dubious use for treating the long-term, chronic pain suffered by so many players — and fining and suspending players who choose instead to self-medicate with a less addictive and non-lethal substance.

The disproportionality of the league’s substance abuse policy was put into stark relief in 2015, when the Cleveland Browns’ Josh Gordon received a year-long suspension for multiple violations of the league’s marijuana ban.

When Baltimore Ravens running back Ray Rice was charged with aggravated assault for beating his fiancée at the time, his initial suspension from the league was only two games.

Christopher Ingraham writes about politics, drug policy and all things data. He previously worked at the Brookings Institution and the Pew Research Centre