Marijuana’s Restrictive Federal Classification Isn’t Supported By Science, New Study Concludes

Marijuana and other drugs are not as dangerous as laws written half a
century ago say they are, according to a new scientific review.

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.

Marijuana, for example, has been listed as a Schedule I drug in the U.S.
for decades. While President Donald Trump signed an executive order
directing the attorney general to expeditiously complete the process of
moving cannabis to a Schedule III substance last month, that has not yet
occurred.

In the new paper published in the December 2025 issue of Harm Reduction
Journal, a multidisciplinary panel of U.S. researchers, clinicians and
people with lived experience of substance use found that federal drug
policy is “poorly aligned with scientific evidence” and often contradicts
expert assessments of risk.

To reach their conclusions, the researchers adapted a method known as
multi-criteria decision analysis. Seventeen experts evaluated 19 commonly
used drugs across 18 categories of harm, ranging from overdose death and
long-term health damage to family disruption, crime and economic cost. Each
drug was scored and weighted to produce an overall harm ranking.

The study—titled “US drug policy does not align with experts’ rankings of
drug harms: a multi-criteria decision analysis”—also found that nearly all
drugs were more harmful to the people who use them than to others, a result
with significant policy implications. “An array of harm reduction
strategies should be considered,” the authors argue, noting that punitive
approaches have coincided with rising overdose deaths rather than declines
in use.

The findings arrive at a moment when federal and state officials are
reconsidering long-standing approaches to drug regulation, sentencing and
public health response.

“For example, cannabis was rated as less harmful than its Schedule I status
suggests.”

By placing cannabis in the most restrictive legal category—while ranking
fentanyl lower in Schedule II and leaving alcohol outside the federal drug
scheduling system entirely—U.S. policy has created a framework that the
authors say no longer reflects either scientific consensus or actual risk
to the population.

“Resources should be focused on health and wellness, not on incarceration,”
they wrote.

Taken together, the study paints a picture of a drug policy frozen in
time—one that treats substances like cannabis and psilocybin as major
threats while failing to adequately respond to the substances doing the
greatest damage. As fentanyl deaths climb and alcohol-related harms
persist, the authors suggest that aligning law with evidence is no longer
just an academic concern, but a public health imperative.

“Psilocybin and cannabis are associated with less harm than many other
drugs and with potential medicinal benefits but people who use them remain
subject to punishment in many jurisdictions.”

The researchers argue that evidence-based scheduling could support a shift
away from punitive enforcement and toward targeted harm reduction, expanded
treatment access and public health interventions, particularly for fentanyl
and alcohol.

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

Calling for further examination, the authors write that the research
“provides a useful starting point for future work in the U.S. that could
account for additional drugs, drug benefits, vulnerable subpopulations
(e.g., youth), and various methods of use and routes of ingestion.”

“Collectively, this work can be used to advance scientific debate about the
best ways to reduce harms to people who use drugs and to redress societal
impacts at the same time.”

The study comes on the heels of the Trump administration backing away from
a prior federal recommendation to limit alcohol consumption to specific
amounts, even as marijuana remains federally criminalized and more
Americans are choosing cannabis for personal health reasons.

More changes are also on the horizon. President Trump signed a bill into
law last year containing provisions that would remove barriers to
conducting research into the risks and benefits of marijuana, psychedelics
and other Schedule I drugs.

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Science, New Study Concludes appeared first on Marijuana Moment.