It's been almost two years since the Drug Enforcement Administration (DEA) began accepting applications for new growers of research cannabis, and two dozen applicants are still in regulatory limbo.

Since the DEA announced in August 2016 that it would end the federal monopoly on producing cannabis for scientific research in the United States, growers, investors, researchers, applicants, and even members of Congress have sought to understand why a relatively simple licensing review process has stretched on for nearly two years. The answer is pretty straightforward: Attorney General Jeff Sessions, for reasons he has not publicly disclosed, decided to intervene in a process that has historically not involved the attorney general in order to stop the DEA from issuing licenses to growers.

While the Controlled Substances Act gives the attorney general regulatory authority over scheduled drugs, that authority has historically been delegated to the DEA, which is part of the Justice Department. The DEA has a whole division, in fact, dedicated to "investigat[ing] the diversion of controlled pharmaceuticals and listed chemicals from legitimate sources while ensuring an adequate and uninterrupted supply for legitimate medical, commercial, and scientific needs."

Members of Congress are not happy with Sessions' obstruction of the licensing process. In April, Sens. Orrin Hatch (R–Utah) and Kamala Harris (D–Calif.) sent the attorney general a letter in which they asked him to provide the Senate with a timeline for processing applications from potential manufacturers of research marijuana. They also asked the DOJ to update applicants on the review process. Both actions, Hatch and Harris suggested, should be completed by May 15, 2018. Not only did the DOJ miss that deadline, but it doesn't seem interested in playing catch-up.

Four license applicants I interviewed in late June told me they've received no official updates from either the DEA or the DOJ in months. Applicants who have spoken to congressional offices working on this issue say their contacts are equally frustrated by Sessions' obstruction of the DEA's licensing process.

(Reason obtained the identities of the 26 initial applicants through a Freedom of Information Act request to the DEA. Reason is not identifying which applicants provided information for this story so as not to jeopardize their chances of approval. )

"No 'formal' communication for months," one applicant told me by email. "They do answer questions I've asked, although on a limited basis."

"No formal communication," another told me. "Hoping to hear more soon."

"Just silence," a third applicant told me over email.

The Hatch-Harris letter captures both the widespread support for studying cannabis and the disproportionate power Sessions has to maintain the status quo. "Expanded research has been called for by President Trump's Surgeon General, the Secretary of Veterans Affairs, the FDA, the CDC, the National Highway Safety Administration, the National Institute of Health, the National Cancer Institute, the National Academies of Sciences, and the National Institute on Drug Abuse," the senators wrote. "In order to facilitate such research, scientists and lawmakers must have timely guidance on whether, when, and how these manufacturers' applications will be resolved."

The rapid pace of marijuana legalization at the state level, meanwhile, might seem to lessen the need for federally licensed growers of research cannabis. Can't researchers just use the myriad cannabis products available in the 30 states that allow recreational or medical use? They cannot.

Researchers who want to test cannabis products in humans must comply with federal regulations governing the handling of Schedule I controlled substances. Those regulations require researchers who would like to use domestically produced marijuana to obtain their material from a federally licensed grower. For decades now, there has been only one such grower: Mahmoud ElSohly at the University of Mississippi, who operates under a contract with the National Institute on Drug Abuse (NIDA). The hundreds of researchers who are licensed by the federal government to study marijuana in the U.S. must use material obtained from NIDA, despite credible concerns about quality control and the agency's ability to provide material that reflects the diversity of products available to consumers in medical and recreational dispensaries across the country.

No other field of drug research or development requires that all pharmaceutical companies and academic institutions that would like to source their materials domestically get them from one person chosen by the federal government. To see the impact on the U.S. drug industry, one need look no further than the U.K., which produced Epidiolex, the first marijuana-derived drug to ever be approved by the Food and Drug Administration.

Could GW Pharmaceuticals, the maker of Epidiolex, have brought its drug to market if its research had used cannabis grown at the University of Mississippi? Stephen Schultz, the company's vice president of investor relations, wouldn't speculate. He did say, however, that the U.K.'s cannabis regulations are essential to the company's drug development strategy. "We develop medicines that have a very specific cannabinoid profile," Schultz said. "So it is very important that we be in complete control of creating our medicines, from growing to extracting."

What's more, it won't be possible to get FDA approval for a cannabis-derived medicine made in the United States until new manufacturers are approved, since the material used in Phase III clinical trials must be identical to the material used in the medicine. In other words, NIDA marijuana cannot be used in Phase III trials.

In August 2016, it seemed like the U.S. might finally allow a market for research cannabis. That month, the DEA, which for years had resisted attempts to create such a market, announced that it would begin accepting applications for additional licenses to manufacture research marijuana. "Although no drug product made from marijuana has yet been shown to be safe and effective," the notice in the Federal Register said, the DEA "fully supports expanding research into the potential medical utility of marijuana and its chemical constituents."

Some two dozen entrepreneurs and companies submitted lengthy applications in the months that followed that announcement. Many submitted additional information at the DEA's request. Two applicants told me they'd raised millions in funding, and several others said they'd made intellectual property arrangements with cannabis growers and researchers overseas. Plots of land were scouted and buildings were leased.

But enthusiasm quickly gave way to anxiety after Sessions was confirmed as attorney general in February 2017. That August, anxiety turned to dread when The Washington Post reported that Acting DEA Administrator Chuck Rosenstein had resigned after butting heads with Sessions over research cannabis. Rosenstein was reportedly in favor of approving new licenses, but Sessions brought the review to a screeching halt.

The Washington Post story eventually made its way to Hatch, who asked Sessions at a hearing in October 2017 why the DOJ had yet to license new growers of cannabis for pharmaceutical research. During their brief exchange, Sessions told Hatch it would be "healthy to have some more competition in the supply" of research marijuana, but the DOJ was not going to approve all 26 applicants. I contacted Hatch's office twice for comment but received no response.

Sessions suggested that the DEA lacked the capacity to supervise even a handful of additional cannabis manufacturers. That claim sounds spurious considering that the DEA routinely approves applications to manufacture Schedule I and II substances other than marijuana. The agency approved eight such manufacturing applications in June 2018, seven in May 2018, eight in April 2018, and three in February 2018. (One applicant familiar with the DEA's licensing process told me the cost of supervising additional license holders is probably marginal.)

Senators questioned the attorney general again in April 2018. At that hearing, Sessions came up with another excuse for not allowing the DEA to move forward. This time, he claimed approving additional marijuana growers might violate a United Nations treaty signed by the U.S. This claim is almost certainly not true even under the most literal and conservative reading of that treaty.

One more deadline looms. Hatch and Harris would like to see Sessions act on all outstanding applications, either approving or rejecting them, by August 11, 2018, the two-year anniversary of the DEA's announcement in the Federal Register. By comparison, it took the DOJ less than six months to process the controlled substance manufacturing applications it approved in June, one of which was for making synthetic marijuana.

If Sessions blows the August deadline, he won't just be smiting a crop of would-be cannabis entrepenuers. He will be standing in the way of medical progress and punishing patients and their families in the process.