Science & Health

Marijuana’s Federal Restrictions Lack Scientific Support, Study Finds

Published on January 20, 2026

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According to a recent scientific review, marijuana and other substances are significantly less harmful than federal laws written half a century ago indicate.

Since the passage of the Controlled Substances Act (CSA) in 1970, U.S. drug laws have been dictated by rigid categories that supposedly reflect the dangers posed by different substances—but the new study suggests that “drug policy contradicts expert assessments of drug harms” both in America and across the world.

The results indicate that governments’ legal rankings for substances bear little resemblance to what experts actually know about which drugs cause the most harm—something that cannabis consumers and much of the general public have long recognized.

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Marijuana has been classified as a Schedule I drug in the U.S. for decades. Although President Donald Trump signed an executive order last month directing the attorney general to swiftly reclassify cannabis as a Schedule III substance, that change has not yet been implemented.

A new study published in the December 2025 issue of Harm Reduction Journal finds that U.S. federal drug policy is “poorly aligned with scientific evidence” and often contradicts expert assessments of risk. The research was conducted by a multidisciplinary panel of U.S. scientists, clinicians, and individuals with lived experience of substance use.

Using a method called multi-criteria decision analysis, 17 experts assessed 19 commonly used drugs across 18 categories of harm—including overdose risk, long-term health effects, family disruption, crime, and economic impact. Each drug was scored and weighted to create an overall harm ranking.

The study, titled “US drug policy does not align with experts’ rankings of drug harms: a multi-criteria decision analysis,” found that most drugs are more harmful to the users themselves than to others—highlighting important policy implications. The authors argue that “an array of harm reduction strategies should be considered,” noting that punitive approaches have coincided with rising overdose deaths rather than reduced use.

These findings come at a time when both federal and state policymakers are rethinking long-standing approaches to drug regulation, sentencing, and public health interventions.

“According to the study, cannabis poses lower risks than are implied by its Schedule I designation Short & Catchy.”

By putting cannabis in the most restrictive category, while placing fentanyl in Schedule II and leaving alcohol unscheduled at the federal level, U.S. policy has created a system that the study’s authors say does not reflect scientific consensus or actual risks.

“Resources should prioritize health and wellness over incarceration,” the authors wrote.

Overall, the study portrays U.S. drug policy as outdated—treating cannabis and psilocybin as serious threats while ignoring the substances causing the most harm. With fentanyl deaths rising and alcohol-related problems continuing, the authors argue that updating the law to reflect evidence is now a public health necessity, not just an academic issue.

“Psilocybin and cannabis cause less harm than many other drugs and may offer medicinal benefits, yet users are still criminalized in many areas.”

The researchers suggest that scheduling drugs based on evidence could move policy away from punishment and toward harm reduction, better treatment access, and public health measures—especially for fentanyl and alcohol.

Noting that “fentanyl was deemed the most harmful drug,” the researchers highlight evidence supporting naloxone distribution, fentanyl test strips, and supervised consumption sites.

The authors urge further research, noting that their study “provides a useful starting point for future work in the U.S., which could examine additional drugs, their benefits, vulnerable populations like youth, and various methods and routes of use.”

“Together, this research can help guide scientific discussion on how to reduce harm for drug users while addressing broader societal impacts.”

The study comes as the Trump administration retreats from previous federal guidance limiting alcohol intake, even as marijuana remains federally criminalized and an increasing number of Americans turn to cannabis for personal health reasons.

More changes could be on the way. Last year, President Trump signed legislation containing provisions designed to eliminate barriers to research on the risks and benefits of marijuana, psychedelics, and other Schedule I substances.

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