In May 2012, researchers from the University of California‘s Center for Medicinal Cannabis Research (CMCR) at UC San Diego published a review in The Open Neurology Journal concluding that marijuana’s Schedule I classification “is not tenable.” Drawing on the center’s own clinical trials, Igor Grant and three colleagues argued that cannabis has real medical value for neuropathic pain and multiple sclerosis spasticity, and that its abuse profile looks more like Schedule III drugs such as codeine.
What Happened
The paper, “Medical Marijuana: Clearing Away the Smoke,” by Igor Grant, J. Hampton Atkinson, Ben Gouaux and Barth Wilsey, appeared online May 4, 2012 (Open Neurology Journal, 2012;6:18-25). Grant directed the CMCR. The review summarized a decade of research, starting from the point that as recently as the early 2000s only nine randomized studies of acceptable quality on cannabinoids for pain and spasticity existed worldwide.
Its key passage was blunt: “Based on evidence currently available the Schedule I classification is not tenable; it is not accurate that cannabis has no medical value, or that information on safety is lacking.” The authors added that cannabis “has some abuse potential, but its profile more closely resembles drugs in Schedule III (where codeine and dronabinol are listed),” and that Schedule I status and the continuing controversy were “obstacles to medical progress” (full text, PMC).
The review also noted that fatal overdose from cannabis alone had not been reported, while cautioning that dependence, a withdrawal syndrome, psychiatric risks in vulnerable people and traffic safety were real concerns. It offered doctors a decision guide for when cannabis might be recommended where state law allowed it.
Background: The CMCR Trials
California created the CMCR through the Medical Marijuana Research Act of 1999. Its trials ran under federal oversight from the National Institute on Drug Abuse and the FDA, using cannabis cigarettes with 1% to 8% THC compared with placebo cigarettes that had the THC extracted. The studies, several of them published in journals such as Neurology and the Journal of Pain, found short-term pain relief in HIV-related and other neuropathic pain, and one CMCR study found reduced spasticity in multiple sclerosis patients. Our pages on cannabis for neuropathy and multiple sclerosis research cover those trials and later ones.
The paper landed at a tense moment. A month later, on June 20, 2012, DEA Administrator Michele Leonhart refused to tell Congress whether heroin was worse than marijuana. Americans for Safe Access was in federal court challenging the DEA’s 2011 denial of a rescheduling petition, and Rep. Barney Frank’s H.R. 1983, the States’ Medical Marijuana Patient Protection Act, which would have rescheduled marijuana, sat in committee.
What Happened Next
None of those efforts moved federal policy quickly. H.R. 1983 never got a vote, and on January 22, 2013, the D.C. Circuit upheld the DEA’s denial in the case we cover in our history of the Coalition for Rescheduling Cannabis petition. The review’s argument aged well, though. In August 2023 the Department of Health and Human Services recommended moving marijuana to Schedule III, the same category the CMCR authors had pointed to more than a decade earlier.
Where It Stands in 2026
An April 2026 DOJ and DEA order moved FDA-approved marijuana products and marijuana held under a state medical marijuana license to Schedule III. Adult-use and unlicensed marijuana remain in Schedule I, and a DEA hearing on rescheduling all marijuana was stayed on September 29, 2026. Our explainer on why marijuana is Schedule I and our federal marijuana law guide track the latest.
Center for Medicinal Cannabis Research Study FAQ
What did the 2012 CMCR study conclude?
That Schedule I classification for marijuana “is not tenable,” because evidence showed medical value for neuropathic pain and MS spasticity and an abuse profile closer to Schedule III drugs.
What is the Center for Medicinal Cannabis Research?
A University of California research center at UC San Diego created under California’s Medical Marijuana Research Act of 1999 to run clinical trials of cannabis.
Is marijuana still Schedule I?
Partly. Since April 2026, state-licensed medical marijuana and FDA-approved products are Schedule III, while adult-use marijuana remains Schedule I.
Originally reported by The Weed Street Journal; rewritten and updated in October 2026 with what happened next.
