Though marijuana has been legalized — at least for medical use — in more than half the country, it remains outlawed by the federal government, which still considers cannabis on a par with heroin. First-term Congresswoman Ilhan Omar of Minnesota said Saturday morning that she believes it is time for the U.S. to not only legalize pot on a countrywide basis, but to retroactively clear the criminal records of those previously jailed on marijuana charges.

Barr Says He'd 'Favor One Uniform Federal Rule Against Marijuana'

"Cannabis criminalization disproportionately impacts communities of color," wrote Omar on Twitter Saturday morning. "We must finally legalize cannabis nationwide and expunge records for those incarcerated for cannabis-related offenses."

According to the American Civil Liberties Union, Omar's statement about marijuana arrests disproportionately affecting people of color was accurate. ACLU research found that, between 2001 and 2010, black people were four times more likely to be arrested on marijuana-related charges than whites, despite the fact that cannabis was used by the same percentage of people in either racial demographic.

Even if all 50 states were to legalize recreational use, its continued status as a Schedule I drug at the federal level would mean that the Drug Enforcement Administration could arrest individuals and shutter businesses for violating federal law.

For several years, Congress has effectively barred the DEA from intervening in states that had legalized medical marijuana, including stipulations in government funding bills that temporarily prohibited the Justice Department from using any congressionally appropriated funds to prevent these states from "implementing their own laws that authorize the use, distribution, possession, or cultivation of medical marijuana."

In 2017, then-Attorney General Jeff Sessions, an outspoken opponent of marijuana, wrote to Congress, unsuccessfully asking for lawmakers to end this prohibition and let the DEA go after state-legalized pot operations.

"I believe it would be unwise for Congress to restrict the Department to fund particular prosecutions, particularly in the midst of an historic drug epidemic and potentially long-term uptick in violent crime," read the letter. "The Department must be in a position to use all laws available to combat the transnational drug organizations and dangerous drug traffickers who threaten American lives."

Expect legalization to be a topic of discussion during the 2020 presidential campaign. Nearly all the current Democratic nominees either openly support legalization at the national level or believe the federal government should not interfere in states where the drug has been legalized. Some, including Senator Cory Booker, have introduced or backed legislation intended to legalize pot nationwide.

Trump, during the 2016 campaign, stated his support for medical marijuana, but his subsequent hiring of Sessions as attorney general raised questions about the president's actual intentions. His subsequent naming of William Barr to replace Sessions did little to alleviate these concerns. At a recent hearing before the Senate, Barr testified that he was in favor of a federal law prohibiting pot nationwide.

"Personally, I would still favor one uniform federal rule against marijuana," Barr said during the hearing. "But if there is not sufficient consensus to obtain that then I think the way to go is to permit a more federal approach so states can, you know, make their own decisions within the framework of the federal law. So we're not just ignoring the enforcement of federal law."

A marijuana plant in Vancouver, Canada, on October, 17, 2018.DON MACKINNON/AFP/Getty Images