APPLETON, Wis. — In a significant shift in federal drug policy, President Donald Trump signed an executive order on Thursday reclassifying cannabis from a Schedule I substance to a Schedule III drug, a move that scientists say could dramatically expand research into the plant's potential medical benefits and risks.
The order, which builds on regulatory efforts initiated during the Biden administration, aims to address decades of restrictions that have hampered studies on marijuana, the most widely used federally illegal substance in the United States. 'Decades of federal drug control policy have neglected marijuana’s medical uses,' the executive order states. 'That oversight has limited the ability of scientists and manufacturers to complete the necessary research on safety and efficacy to inform doctors and patients.'
This reclassification does not legalize cannabis at the federal level but is expected to ease barriers for medical research. According to Gallup polls from 2023 and 2024, an estimated 15% of U.S. adults now smoke marijuana, a notable increase from 7% in 2013. Usage is particularly high among young adults aged 18 to 34, where it reaches 19%, a demographic for which research has identified potential psychiatric harms.
A study published Tuesday in the journal Pediatrics highlighted these concerns, finding that even using marijuana as infrequently as once or twice a month is associated with emotional distress and poorer school performance among teenagers. Medical marijuana, however, is commonly prescribed for conditions such as chronic pain, nausea and vomiting in chemotherapy patients, and stimulating appetite in those with certain illnesses.
Experts in the field expressed optimism about the policy change. Ziva Cooper, director of the Center for Cannabis and Cannabinoids at the University of California, Los Angeles, described the current research environment as severely constrained. 'It is extremely difficult to study cannabis, aka marijuana, for both the potential adverse effects as well as therapeutic effects,' Cooper said. She noted that the cannabis industry is evolving rapidly, with consumer behaviors shifting alongside it, making it challenging for public health researchers to keep pace.
Even in cannabis-friendly states like California, where Cooper works, federal restrictions persist. 'Researchers cannot test what is readily available to the market, just basic questions about what is in those products that are available in the dispensary I can see outside of my laboratory window, for example,' she added. 'It also means that there are certain restrictions with respect to where we can get our cannabis that we do research on.'
The Drug Enforcement Administration categorizes controlled substances into five schedules, with Schedule I being the most restrictive. This group, which previously included cannabis alongside drugs like ecstasy, heroin, LSD, and peyote, is defined by having 'no currently accepted medical use and a high potential for abuse.' Schedule III, by contrast, encompasses substances like ketamine, testosterone, and anabolic steroids, which carry a 'moderate to low potential for physical and psychological dependence.'
Federal funding for cannabis-related research has been increasing, though still limited by bureaucratic hurdles. Last year, the National Institutes of Health allocated $75 million to therapeutic cannabinoid research, up from $70 million in 2023. Additionally, $217 million supported studies on cannabinoids — the chemical compounds in cannabis — and $53 million went toward research on cannabidiol, or CBD, a non-psychoactive component.
Dr. Brooke Worster, medical director of the M.S. in medical cannabis science and business program at Thomas Jefferson University in Philadelphia, pointed out that much of the existing cannabis research relies on observational methods rather than the rigorous clinical trials demanded for pharmaceuticals. Findings from these studies have been inconsistent. For instance, a 2024 study in the journal Current Alzheimer Research suggested that recreational cannabis use among adults aged 45 and older was linked to a 96% lower risk of subjective cognitive decline compared to nonusers.
In contrast, a 2025 study published in JAMA Network Open reported that heavy cannabis users aged 22 to 36 exhibited impaired working memory. Another study this year in Biomedicines described cannabinoids as a 'promising' alternative to opioids for managing chronic pain but emphasized the need for large-scale, randomized controlled trials. Meanwhile, research from last year in JAMA Network Open observed rising rates of cannabis-related disorders among older Medicare-insured adults, with increased health care visits from 2017 through 2022.
The reclassification is poised to enable more precise investigations. Worster explained that researchers will now be able to dispense and study specific formulations of marijuana, addressing variations in quality and potency across dispensaries, even in states with medical programs. 'We can actively track immediate symptoms or blood levels of things, longer-term effects,' she said. 'All the things you’d want to do when you’re studying a medication, all the things that the federal government otherwise requires us to do to study a medication.'
Not all experts agree that U.S. policy has been the sole barrier to discovering marijuana's full potential. Jonathan Caulkins, the H. Guyford Stever university professor of operations research and public policy at Carnegie Mellon University in Pittsburgh, argued that administrative obstacles haven't prevented breakthroughs elsewhere. 'They do not restrict research in Canada or France or Israel,' Caulkins said. 'I don’t think that we should imagine that the only reason cannabis hasn’t become the wonder drug is because of anything about U.S. law, because we’re not the only country in the world that has a pharmaceutical industry and a research base.'
Despite these differing views, the policy change underscores new responsibilities for the medical community. Worster cautioned that while marijuana may offer benefits for some, products like smoked or inhaled cannabis aren't suitable for everyone. 'What still needs to be figured out is, how do we get the right patient the right medication and the right guidance?' she said. 'The products out there are, a lot of times, not regulated. There are real risks with mental health, with youth who use it too regularly, certainly some cardiovascular effects that we need to pay more attention to.'
The roots of these regulatory challenges trace back to the Nixon administration and the Controlled Substances Act of 1970, which classified cannabis as a Schedule I drug. Nearly 55 years later, much of its medical potential — or limitations — remains underexplored. In Worster's view, under the previous law, 'it is simply a drug of abuse.'
Susan Ferguson, director of the Addictions, Drug and Alcohol Institute at the University of Washington School of Medicine, anticipates that the shift will streamline the research process. Currently, studying Schedule I drugs requires separate, substance-specific licenses involving extensive protocols and DEA inspections. 'It involves extensive writing of protocols,' Ferguson said. 'It involves DEA agents coming out and inspecting the lab and talking to me about the research and the plans for the experiments. It gets very, very complicated.'
With cannabis now in Schedule III, Ferguson believes it will 'open the floodgates' for clinical research, potentially increasing participant enrollment since people may be more willing to join studies on less stigmatized drugs. She compared cannabis to alcohol and tobacco, substances whose risks are well-documented thanks to thorough research. 'We haven’t done that research on cannabis,' Ferguson said. 'It’ll be able to ultimately tell people what are the risks, what are the benefits, and just give people more information.'
It's unclear how the reclassification will impact funding for recreational marijuana studies, but the broader implications could reshape public health approaches. As cannabis use continues to rise amid varying state laws — with recreational sales legal in 24 states and medical programs in 38 — this federal adjustment arrives at a pivotal moment. Researchers and policymakers alike will be watching to see how it influences everything from treatment options to regulatory frameworks in the years ahead.