Last verified: April 2026

The Schedule I Catch-22

The central barrier to cannabis research in the United States has been a regulatory paradox. The Controlled Substances Act of 1970 classified cannabis as Schedule I — defined as having "no currently accepted medical use" and "a high potential for abuse." To conduct research that might demonstrate medical use (and thereby justify reclassification), scientists need access to cannabis. But because cannabis is Schedule I, obtaining it for research requires navigating a uniquely restrictive regulatory apparatus that no other Schedule I substance faces to the same degree.

The practical barriers are cumulative. Researchers need: a DEA Schedule I researcher registration, an FDA Investigational New Drug (IND) application, institutional review board (IRB) approval, and — until 2021 — approval from a special Public Health Service (PHS) review committee that existed only for cannabis research. No other Schedule I substance required PHS review. The multi-agency approval process could take years, and researchers report that it discouraged entire cohorts of scientists from entering the field.

The catch-22 is logical: cannabis cannot be rescheduled because insufficient evidence supports medical use, but insufficient evidence exists because the scheduling itself obstructs the research that would generate it. This circularity was explicitly identified by the National Academies of Sciences, Engineering, and Medicine (NASEM) in their landmark 2017 report as a critical barrier to scientific progress.

The Ole Miss Monopoly — 1968 to 2021

From 1968 until May 2021, the University of Mississippi held the sole DEA-licensed contract to grow cannabis for federally approved research. The program, housed at the National Center for Natural Products Research under the direction of Mahmoud ElSohly, was the only legal source of research-grade cannabis in the United States for over five decades.

The Ole Miss monopoly became increasingly problematic as the gap between research-grade and commercial cannabis widened. In 2017, Daniela Vergara and colleagues published in Scientific Reports that commercial cannabis strains had reached THC concentrations of 27% or higher, while the Ole Miss product available to researchers was substantially lower in potency and limited in chemical diversity. In 2019, Anna Schwabe and colleagues published a genetic analysis concluding that the Ole Miss material was "more similar to hemp" than to the cannabis consumers were actually using.

The chemical profiles of cannabis available through the NIDA Drug Supply Program are not representative of the cannabis that is commonly available to consumers in state-legal markets.

Vergara et al., Scientific Reports 2017; Schwabe et al., 2019

This meant that federally funded studies were testing a substance that bore little resemblance to what millions of Americans were using — producing research findings of questionable ecological validity. A study using 6% THC Ole Miss cannabis could not inform clinical practice in a market dominated by 20%+ flower, 70%+ concentrates, and a diverse array of edibles, tinctures, and topicals.

The monopoly ended in May 2021 when the DEA finally granted additional cultivation licenses to Groff NA (Massachusetts) and Scottsdale Research Institute (Arizona, founded by Sue Sisley and George Zorn). These new cultivators could grow cannabis that more closely matched commercial products, though the licensing process had taken years and the new supply was initially limited.

NASEM 2017 — The Gold Standard

In January 2017, the National Academies of Sciences, Engineering, and Medicine published The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research — the most comprehensive systematic review of cannabis health evidence ever conducted. The report reviewed thousands of studies and organized its findings into a five-tier evidence hierarchy:

• Conclusive evidence — chronic pain in adults, chemotherapy-induced nausea, MS spasticity (patient-reported)
• Substantial evidence — short-term sleep improvement, Dravet/Lennox-Gastaut epilepsy (CBD)
• Moderate evidence — associations with various conditions (mixed direction)
• Limited evidence — insufficient for firm conclusions but suggestive
• Insufficient evidence — too few or too low-quality studies to draw any conclusion

The report’s most important meta-finding was how little high-quality evidence existed relative to the scope of therapeutic claims made about cannabis. For most conditions listed in state medical cannabis programs, the evidence level was limited or insufficient. Only 8.3% of state qualifying conditions met the NASEM’s "substantial" or "conclusive" evidence standard. The report also identified the Schedule I barrier as a primary reason for this evidence gap and recommended regulatory changes to facilitate research.

NASEM 2017 remains the reference standard for evidence-based cannabis science. Any claim about cannabis’s medical efficacy should be evaluated against the NASEM framework, which provides a clear-eyed assessment of what the evidence actually supports versus what advocates and the cannabis industry claim.

Schedule III — The Rescheduling Timeline

The most significant regulatory development in cannabis science policy has been the rescheduling process initiated during the Biden administration and continued under the Trump administration:

• August 2023 — the Department of Health and Human Services (HHS), following a scientific review by the FDA, formally recommended to the DEA that cannabis be reclassified from Schedule I to Schedule III
• May 2024 — the DEA published a Notice of Proposed Rulemaking (NPRM) to reschedule cannabis to Schedule III, opening a public comment period that received over 43,000 comments
• December 18, 2025 — President Trump signed an Executive Order directing continued rescheduling, signaling bipartisan support for the regulatory change

As of April 2026, the final rule has not been published, and cannabis remains Schedule I pending completion of the administrative rulemaking process. But the direction of travel is clear, and the implications for research are substantial.

What Schedule III Would Change

Rescheduling cannabis from Schedule I to Schedule III would have significant but bounded effects. It is critical to understand what it would and would not change:

What Schedule III means:

• 280E tax relief — IRC Section 280E prohibits businesses trafficking in Schedule I or II substances from deducting ordinary business expenses. For cannabis businesses, this has resulted in effective federal tax rates of 70%+ in some cases. One company estimated the cumulative 280E burden at approximately $38 million. Schedule III removes this tax penalty
• Research facilitation — Schedule III substances can be researched under standard IND protocols without the additional DEA Schedule I researcher registration. This substantially reduces the time and administrative burden of launching cannabis clinical trials
• Multi-site clinical trials — the reduced regulatory burden makes large, multi-site randomized controlled trials — the type needed to generate NASEM "conclusive" evidence — practically feasible for the first time

What Schedule III does NOT do:

• Legalize recreational cannabis — Schedule III substances (e.g., ketamine, testosterone, Tylenol with codeine) are controlled substances that require a prescription; recreational use remains federally illegal
• Create interstate commerce — state cannabis markets would remain state-by-state; transporting cannabis across state lines would still violate the Controlled Substances Act
• Bypass FDA approval — cannabis products would not automatically receive FDA approval for medical use; individual products would still need to go through the standard drug approval process (Phase I–III trials, NDA submission)

The Path Forward

The combination of the Ole Miss monopoly ending, the rescheduling process advancing, and the increasing availability of institutional funding (NIH, state grants, private foundations) is producing a research renaissance. Studies that were logistically impossible five years ago — large RCTs using products representative of the commercial market, multi-site trials with adequate statistical power, pharmacogenomic studies matching patients to optimal cannabinoid profiles — are now feasible or imminent.

The critical question is whether the research will outpace the policy. Forty-plus states have legalized some form of cannabis access based on evidence that NASEM rated as largely "limited" or "insufficient." The research catching up to the policy decisions already made is perhaps the most important task in cannabis science — not to justify those decisions retroactively, but to understand which were correct, which were premature, and how to optimize the therapeutic and minimize the harm of a substance that is already in widespread use regardless of what the evidence ultimately shows.