Arguments Against Marijuana Legalization
TEN REASONS, EACH WITH THE EVIDENCE
If you are looking for the case against legalizing marijuana, this is it in one place: ten arguments, written in plain language, each one tied to a primary source you can check. These are the arguments doctors, researchers, parents and law enforcement make, and the ones the marijuana industry spends the most money trying to answer.
- Today’s marijuana is a different, far stronger drug.
- It is addictive, and legalization means more addiction.
- It raises the risk of psychosis and schizophrenia.
- It damages the heart.
- Kids use more where it is sold, and toddlers end up in the ER.
- More impaired drivers, more road deaths.
- The illegal market grows instead of disappearing.
- The tax money is small and the costs are real.
- The social justice promises were not kept.
- It is Big Tobacco’s playbook, funded by Big Tobacco.
1Today’s marijuana is not the marijuana of the 1970s.
The average THC content of seized marijuana rose from under 4 percent in 1995 to more than 16 percent in 2022, and concentrates sold in legal stores now reach 90 percent THC and above.
Potency is the hinge of the whole debate. Every study of harm from the 1980s and 1990s was done on a drug four or five times weaker than what a dispensary sells today, and the dose-response pattern shows up everywhere researchers look: higher potency means more addiction, more psychosis, more emergency room visits. Legalization did not just make the old drug available. It created a market that competes on strength.
Source: University of Mississippi potency monitoring, summarized in SAM’s Legalization Impact Report 2026-2027; Stanford Medicine (2026) on concentrate potency.
Go deeper: Youth marijuana use
2Marijuana is addictive, and more access means more addiction.
19.3 million Americans met the clinical criteria for marijuana addiction in 2025. About three in ten people who use marijuana develop the disorder, and the risk is far higher for anyone who starts as a teenager.
The medical term is cannabis use disorder, and it is a diagnosis in the same manual that defines alcohol and opioid addiction. Legalization raises the number of users, lowers the perceived risk, and raises potency at the same time, so addiction grows faster than use. Among teenagers, addiction rose 25 percent faster in states that legalized than in states that did not.
Sources: 2025 National Survey on Drug Use and Health; SAMHSA, risks of marijuana use; Kaiser Permanente Division of Research.
Go deeper: Is marijuana addictive?
3It raises the risk of psychosis and schizophrenia.
Daily use of high-potency marijuana is associated with a fourfold higher risk of a psychotic disorder, and the National Academies of Sciences found “substantial evidence” linking marijuana use to schizophrenia and other psychoses.
This is the finding the industry most wants buried, and it is the one with the deepest research base. The link is dose-dependent: the more often a person uses and the stronger the product, the higher the risk. Since states began legalizing, psychosis-related hospital care has risen in those states, and a Danish national study found that as many as three in ten schizophrenia cases among men in their twenties could have been prevented by preventing marijuana addiction.
Sources: Di Forti et al., The Lancet Psychiatry, 2019; National Academies, 2017; Elser et al., JAMA Network Open, 2023; Hjorthøj et al., Psychological Medicine, 2023.
Go deeper: Marijuana and mental health · Deep dive: psychosis
4It damages the heart.
Daily marijuana use is associated with 25 percent higher odds of heart attack and 42 percent higher odds of stroke. A 2025 review of 24 studies found marijuana use linked to a doubling of cardiovascular death.
For decades marijuana was sold as the safe alternative to tobacco. The cardiology literature now says otherwise. THC raises heart rate and blood pressure, impairs the lining of the arteries, and the risk holds for people who never smoked tobacco. Edibles are not exempt; the vascular damage in edible users was as bad or worse.
Sources: Jeffers et al., Journal of the American Heart Association, 2024; Storck et al., Heart (BMJ), 2025.
Go deeper: Deep dive: marijuana and heart health
5Kids use more where marijuana is sold, and toddlers end up in the ER.
All eleven states with the highest teen marijuana use have legal recreational marijuana. Emergency calls for young children who ate marijuana edibles rose 1,375 percent from 2017 to 2021.
Legalization advocates promised that regulation would keep marijuana away from kids. The opposite happened. Stores, billboards and gummies normalized the drug, teen addiction diagnoses in California flipped from a yearly decline to a yearly rise after the 2016 vote, and pediatric poisonings became routine. About half of teenagers who use marijuana now meet criteria for addiction.
Sources: NSDUH state estimates, 2023-2024; Tweet et al., Pediatrics, 2023; Kaiser Permanente, 2026.
Go deeper: Youth marijuana use: the data · Parent Action Network
6More stoned drivers, more deaths on the road.
In Colorado, the share of traffic deaths involving a driver who tested positive for marijuana rose from 9 percent in 2000 to 21.5 percent in 2018. One in four Colorado road deaths now involves marijuana.
There is no roadside test for marijuana impairment the way there is for alcohol, and surveys show most users believe they will not be caught. Washington saw the share of fatal-crash drivers who had used marijuana double after legalization. Canada, which legalized nationally, now finds THC in injured drivers more often than alcohol.
Sources: Colorado Department of Transportation and Rocky Mountain HIDTA data, AAA Foundation for Traffic Safety, summarized with citations in SAM’s Legalization Impact Report.
7The illegal market does not go away. It grows.
In California, the largest legal market in the country, illegal grows outnumber legal ones by as much as ten to one, and most of what is grown is shipped to states where marijuana is still illegal.
Legalization was supposed to put the cartels out of business. Instead it gave them cover. Licensed states have become the base for foreign criminal networks, including more than 3,000 illegal grows in Oklahoma tied to organized crime, most of it Chinese. Legal stores compete with untaxed illegal product and lose, which is why California cut marijuana taxes to rescue “failing” businesses.
Sources: Los Angeles Times, DEA National Drug Threat Assessment, Oregon State Police and ProPublica reporting, cited in SAM’s Legalization Impact Report.
Go deeper: Deep dive: marijuana and crime
8The tax money is small and the costs are real.
Marijuana excise taxes have never exceeded 1.5 percent of any state’s tax revenue. In California, marijuana taxes were 0.49 percent of the state budget.
Every legalization campaign leads with revenue. The U.S. Census Bureau’s own accounting shows how little it amounts to: 1.18 percent of tax revenue in Colorado, 0.77 percent in Oregon, 0.62 percent in Vermont. Against that sit the costs of addiction treatment, emergency care, impaired-driving crashes, lost productivity and enforcement of a market that still runs mostly underground. A Colorado analysis put those costs at about $4.50 for every dollar of marijuana tax collected.
Sources: U.S. Census Bureau quarterly tax data and California Department of Tax and Fee Administration, cited in SAM’s Legalization Impact Report; Centennial Institute, Economic and Social Costs of Legalized Marijuana, 2018.
9The social justice promises were not kept.
No one was in federal prison solely for marijuana possession before legalization, and after it, racial disparities in marijuana arrests persisted in every state that legalized.
Legalization was sold as repair for the drug war. The ACLU’s own data show Black Americans were still arrested for marijuana at higher rates in legal states after the law changed. Equity licensing programs in Illinois, New York and Massachusetts left many license holders unable to open for years, while multistate corporations and their investors took the market. Dispensaries cluster in lower-income Black and Hispanic neighborhoods, the same communities that bear the health costs.
Sources: White House background briefing, Oct. 2022; ACLU, A Tale of Two Countries, 2020; Capitol News Illinois.
Go deeper: Marijuana legalization and social justice
10It is Big Tobacco’s playbook, run by Big Tobacco’s money.
Altria, the maker of Marlboro, put $1.8 billion into a marijuana company. British American Tobacco, Constellation Brands and Pfizer followed. The same companies now lobby Congress for rescheduling and a federal tax cut.
The marijuana industry is not a collection of small farmers. It is a publicly traded, addiction-for-profit industry that markets high-potency products, fights potency caps and advertising limits, and spends millions on lobbyists and former lawmakers. The country spent fifty years and millions of lives learning what happens when an addictive product is commercialized and marketed. Legalization asks us to do it again.
Sources: Altria-Cronos agreement, SEC filing; OpenSecrets, marijuana industry lobbying.
Go deeper: Who funds marijuana legalization?
Opposing legalization is not the same as supporting arrests
SAM’s position is the middle road between incarceration and commercialization. No one should go to jail for using marijuana. No company should be allowed to sell 90 percent THC products with cartoon packaging either. The policies that follow from the evidence above:
Civil penalties and treatment referral instead of arrest for personal possession, and expungement of past possession records.
Fund the youth prevention programs and addiction treatment that legalization campaigns promise and legal states underfund.
Where marijuana is already sold, cap THC potency, ban advertising that reaches kids, and let localities keep stores out.
Expand research and approve marijuana-derived medicines the way every other drug is approved, instead of store-based “medical” programs.
Questions people ask about legalizing marijuana
What is the strongest argument against legalizing marijuana?
The health evidence on today’s high-potency marijuana. Daily use of high-potency products is associated with about four times the risk of psychosis, 25 percent higher odds of heart attack and 42 percent higher odds of stroke, and roughly three in ten users become addicted. Legalization creates a commercial industry whose business model depends on frequent, heavy use of exactly those products.
Is marijuana worse than alcohol?
They are different drugs with different harms, and the comparison is a distraction. Alcohol is legal and commercialized, and it kills about 178,000 Americans a year. The question legalization asks is whether to add a second commercialized addictive industry on top of the first one, not whether marijuana is better or worse.
Doesn’t legalization reduce arrests and mass incarceration?
Before legalization, no one was in federal prison solely for marijuana possession, and people serving state time for marijuana alone were a small fraction of prisoners. After legalization, racial disparities in marijuana arrests persisted in every legal state the ACLU studied. SAM supports removing criminal penalties for personal use and expunging past possession records, which does not require creating a commercial industry.
Has marijuana legalization worked anywhere?
No state that legalized has delivered the results its campaign promised. Teen use is highest in legal states, the illegal market is larger than before in California and Oregon, tax revenue has never topped 1.5 percent of any state’s budget, and emergency room visits, psychosis admissions and pediatric poisonings all rose. Since 2022, seven of ten recreational legalization ballot measures have failed.
Does opposing legalization mean putting people in jail for marijuana?
No. Smart Approaches to Marijuana opposes both incarceration for marijuana use and commercial legalization. The policy in between is decriminalization of personal use, treatment and prevention instead of arrest, record expungement, strict limits on potency and marketing, and keeping the drug illegal to sell and advertise.
Can marijuana be legalized just for medical use safely?
FDA-approved medicines made from marijuana components already exist and are available by prescription. State medical programs are a different thing: most sell the same high-potency products as recreational stores, with the same marketing, and the research shows they serve mostly recreational demand. SAM supports research and FDA approval of specific medicines, not store-based programs.
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