DENVER -- A billboard in front of Sports Authority Filed at Mile High is likely to catch the attention of Broncos fans headed to the season opener Thursday.
They might not all agree with the message.
The billboard is calling on the NFL to "stop driving players to drink" by claiming a "safer choice" (marijuana) is "now legal here."
It was paid for by the Marijuana Policy Project, which has called on the NFL to end a ban on marijuana use for players.
"For years, the NFL has been punishing players for using marijuana despite the fact that it is far less harmful than alcohol, a substance widely embraced by the league," said Mason Tvert, director of communications for the Marijuana Policy Project. "The league would never punish a player simply for having a couple beers, so why does it penalize them for using a substance that is less toxic, less addictive, and less likely to contribute to violence?"
The Marijuana Policy Project launched a Change.org petition called on NFL Commissioner Roger Goodell to change its marijuana policy.
Colorado voted to legalize recreational use of marijuana in November with Amendment 64. Medicinal use of marijuana has been legal in Colorado since 2000.
The Justice Department announced last week that it would not seek to block the new recreational marijuana industry so long as it followed guidelines setup by the state. Marijuana is still illegal under federal law.
The state legislature setup rules for marijuana use, which are set to go into effect in about four months. Denver will likely be the only large Front Range community to allow sales of recreational pot.
In April, the Appeals Court of Colorado issued an opinion that employers can fire employees for smoking pot, even while off the clock.
Is marijuana safer than alcohol?
Both sides of the marijuana legalization debate have addressed the issue of safety, specifically is marijuana safer than drinking alcohol.
The bottom line: There is no simple answer.
Pro-marijuana organizations claim pot is safer citing CDC studies that show thousands of people die each year from alcohol-related diseases. It's difficult to find evidence of someone dying from smoking too much pot, the claim.
For example, a study by the Beckley Foundation said that although marijuana use can have negative effects on physical and mental health, “in terms of relative harms it is considerably less harmful than alcohol or tobacco.”
Other studies have looked the effect marijuana has on young people. Many have shown marijuana use among young people can affect the development of their brain. So does drinking alcohol at a young age, wrote Ty Schepis, an assistant professor of psychology at Texas State University recently.
But in an ideal world, young people would neither drink alcohol nor smoke marijuana.
The National Institute on Drug Abuse says smoke from marijuana is unhealthy. "One study found that people who smoke marijuana frequently but do not smoke tobacco have more health problems and miss more days of work than nonsmokers, mainly because of respiratory illnesses," according to their website.
Yet marijuana has been praised for its medicinal uses. Medical marijuana dispensaries have clients who suffer ills ranging from cancer to AIDS to chronic pain. Proponents say the drug's pain-relieving properties offer an alternative for cancer patients undergoing chemotherapy or radiation treatments.
A series of trials published by the University of California Center for Medicinal Cannabis Research last year showed cannabis can help patients suffering from neuropathic pain, commonly caused by degenerative diseases like multiple sclerosis or fibromyalgia. Neuropathic pain is also a common side effect of chemotherapy and radiation.
The National Institute on Drug Abuse, meanwhile, says that marijuana causes an increase in heart rate, which could put users at risk for a heart attack or stroke. Marijuana smoke also contains carcinogens similar to those in tobacco smoke.
CNN contributed to this report.