Most Americans want legal pot. Here's why feds are taking so long to change old rules.

Marijuana remains in an odd legal limbo in the United States, and there's one organization at the center of it: The Drug Enforcement Administration.

The DEA has for decades held that marijuana is among the most dangerous, highly addictive drugs and has no medical value, despite growing state laws, medical evidence and popular opinion to the contrary. The result: Pot is widely available in some states, heavily criminalized in others — and technically federally illegal everywhere.

The confusion could be cleared up by Congress or the courts intervening, said Carmel Shachar, Harvard School of Law professor and the faculty director Health Law and Policy Clinic. But in the absence of bold congressional action on marijuana, experts and advocates are looking to the DEA to make the next move to change the nation's position on pot.

President Joe Biden has said he's one of the people who disagrees with the DEA's categorization of marijuana, and called for a review in 2022, kicking off a bureaucratic slog that could soon change the status quo. Here's what to know:

The DEA classifies drugs and says pot is the worst kind

The DEA says marijuana is classified as a "Schedule I" drug under the Controlled Substances Act, alongside heroin, LSD and ecstasy.

The statute classifies drugs from Schedule I to Schedule V based on their potential for abuse, addictiveness and medical use. Schedule I drugs have "high potential for abuse and the potential to create severe psychological and/or physical dependence" and "no currently accepted medical use," the DEA says.

"Cocaine, morphine, and methamphetamines are all Schedule II, meaning they have been determined to have some medical value. It feels very strange to have marijuana be more restricted than these substances," Shachar said.

Putting marijuana in Schedule I also places huge obstacles in the way of doing the kind of research that would be needed to prove there are medical uses, according to Heather Trela, the director of operations and a fellow at the Rockefeller Institute of Government out of the State University of New York.

Health risks:Is marijuana more harmful to your lungs than cigarettes? A study suggests it may be.

That's created a feedback loop: It's hard to study pot to prove its medical value, because the federal government says it has no medical value.

Why is pot classified as the most dangerous? No good reason, experts say.

Marijuana has been a Schedule I drug since the statute went into effect in 1971, "with very little medical or scientific evidence to demonstrate why it had to be Schedule I," said Shachar.

At the time, it had more to do with "who uses the drug than the drug itself," said Trela.

It was under President Richard Nixon that marijuana was added to the list under the most restricted category – first, only provisionally until more of the science could be settled, Trela said.

Yet even when a commission formed by Nixon determined weed shouldn't be criminalized, it remained in Schedule I. Trela said Nixon knew marijuana was a "drug associated with the anti-war protesters, hippies and people of color – none of whom were fans of President Nixon and his agenda."

A top adviser to Nixon, John Ehrlichman, said as much in an interview in 1994 that was published by Harper's Magazine in 2016: "Did we know we were lying about the drugs? Of course we did."

What could happen next? Will the DEA change its mind?

The next expected development is considered by advocates as a small step: The DEA is currently considering reclassifying marijuana as a lower-level controlled substance, but that wouldn't make it legal.

"It's a step in the right direction but, in terms of its practical direction, it's really more symbolic," said Morgan Fox, political director for the National Organization for the Reform of Marijuana Laws, the country's oldest cannabis legalization advocacy group.

In 2022, President Joe Biden asked his Department of Health and Human Services to conduct a review of how marijuana is classified, and HHS recommended last year that cannabis be rescheduled as a Schedule III substance, like ketamine, testosterone, anabolic steroids or Tylenol with codeine.

If marijuana is put in Schedule III instead, it would mean it could be legally prescribed by licensed health care providers and dispensed at licensed pharmacies. It could also help resolve a massive federal tax burden that's been placed on cannabis companies.

"It partially sends a signal that the federal government doesn't think cannabis is the worst of the worst drugs. 'Not as bad as heroin;' that's a good thing for the government to say," said Jay Wexler, a law professor at Boston University who wrote the book "Weed Rules: Blazing the Way to a Just and Joyful Marijuana Policy."

But practically, rescheduling wouldn't have much of an effect on state cannabis programs at all, Wexler said, and "everything states are doing is still a violation of federal law, and anybody who's selling, buying, processing, growing cannabis under these state programs is still in violation of federal law even if it's rescheduled."

The DEA did not give a timeframe on if or when an announcement on rescheduling might come when reached by USA TODAY on Wednesday.

What would it take to make marijuana fully legal in the US?

To eliminate the stark conflict between state and federal laws, marijuana would need to be removed from the Controlled Substances Act list altogether. Experts say there's a chance that could happen eventually, but it's still a long way off.

"I think it's going to take time, but I think we will get there," Trela said.

Just as alcohol and tobacco are not considered controlled substances, but are regulated by the federal government and by states, descheduling cannabis could have a similar effect, Wexler said.

A group of Democratic senators – plus Bernie Sanders, who is an independent but joins with Democrats on major issues – wrote a letter to Attorney General Merrick Garland and DEA Administrator Anne Milgram last month urging the descheduling of marijuana.

What's taking so long?

Public support for the legalization of marijuana is at an all-time high, national polling has shown. A Gallup poll conducted in the fall found 70% of Americans support legal weed. In 2022, Pew Research Center found just 10% of Americans believe it should be completely illegal, while 30% support medical use only and 59% supported legalization for medical and recreational use.

That public support has been bumped by Americans seeing first-hand through loved ones and news stories that marijuana can have medical benefits for people with illnesses who can't get any relief otherwise, Wexler said.

"Why doesn't that translate into clear political outcomes to deschedule cannabis? I don’t know," Wexler said.

Experts said a combination of factors may be at play, including a desire to move toward full legalization incrementally. Legalization is also up against a number of top-line priorities, and support from the public and lawmakers is not uniform, Trela said.

"There is still a perception by many and belief that this is not where we should be going; the government should not be encouraging drug use, in their minds," Trela said. "We're not that far removed from the stigma of marijuana."

And, while many states and physicians have recognized marijuana's potential medical benefits, there are still health risks associated with the substance under study, and a lot of unknowns.

Advocates are hopeful weed will be removed from the Controlled Substances Act altogether some day, but it doesn't look like marijuana will be legalized on the federal level anytime soon.

"Rescheduling is a step forward, but it is not nearly enough. And there's no reason to keep cannabis in the Controlled Substances Act," Wexler said.