should marijuanas be legalized essay

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Americans overwhelmingly say marijuana should be legal for medical or recreational use

With a growing number of states authorizing the use of marijuana, the public continues to broadly favor legalization of the drug for medical and recreational purposes. 

An overwhelming share of U.S. adults (88%) say either that marijuana should be legal for medical and recreational use by adults (59%) or that it should be legal for medical use only (30%). Just one-in-ten (10%) say marijuana use should not be legal, according to a Pew Research Center survey conducted Oct. 10-16, 2022. These views are virtually unchanged since April 2021.

The new survey follows President Joe Biden’s decision to pardon people convicted of marijuana possession at the federal level and direct his administration to review how marijuana is classified under federal law. It was fielded before the Nov. 8 midterm elections, when two states legalized the use of marijuana for recreational purposes – joining 19 states and the District of Columbia , which had already done so.

Pew Research Center asked this question to track public views about the legal status of marijuana. For this analysis, we surveyed 5,098 adults from Oct. 10-16, 2022. Everyone who took part in this survey is a member of the Center’s American Trends Panel (ATP), an online survey panel that is recruited through national, random sampling of residential addresses. This way nearly all U.S. adults have a chance of selection. The survey is weighted to be representative of the U.S. adult population by gender, race, ethnicity, partisan affiliation, education and other categories. Read more about the ATP’s methodology .

Here are the questions used for this report, along with responses, and its methodology .

Over the long term, there has been a steep rise in public support for marijuana legalization, as measured by a separate Gallup survey question that asks whether the use of marijuana should be made legal – without specifying whether it would be legalized for recreational or medical use. This year, 68% of adults say marijuana should be legal , matching the record-high support for legalization Gallup found in 2021.

There continue to be sizable age and partisan differences in Americans’ views about marijuana. While very small shares of adults of any age are completely opposed to the legalization of the drug, older adults are far less likely than younger ones to favor legalizing it for recreational purposes.

This is particularly the case among those ages 75 and older, just three-in-ten of whom say marijuana should be legal for both medical and recreational use. Larger shares in every other age group – including 53% of those ages 65 to 74 – say the drug should be legal for both medical and recreational use.

Republicans are more wary than Democrats about legalizing marijuana for recreational use: 45% of Republicans and Republican-leaning independents favor legalizing marijuana for both medical and recreational use, while an additional 39% say it should only be legal for medical use. By comparison, 73% of Democrats and Democratic leaners say marijuana should be legal for both medical and recreational use; an additional 21% say it should be legal for medical use only.

Ideological differences are evident within each party. About four-in-ten conservative Republicans (37%) say marijuana should be legal for medical and recreational use, compared with a 60% majority of moderate and liberal Republicans.

Nearly two-thirds of conservative and moderate Democrats (63%) say marijuana should be legal for medical and recreational use. An overwhelming majority of liberal Democrats (84%) say the same.

There also are racial and ethnic differences in views of legalizing marijuana. Roughly two-thirds of Black adults (68%) and six-in-ten White adults say marijuana should be legal for medical and recreational use, compared with smaller shares of Hispanic (49%) and Asian adults (48%).

Related: Clear majorities of Black Americans favor marijuana legalization, easing of criminal penalties

In both parties, views of marijuana legalization vary by age

While Republicans and Democrats differ greatly on whether marijuana should be legal for medial and recreational use, there are also age divides within each party.

A 62% majority of Republicans ages 18 to 29 favor making marijuana legal for medical and recreational use, compared with 52% of those ages 30 to 49. Roughly four-in-ten Republicans ages 50 to 64 (41%) and 65 to 74 (38%) say marijuana should be legal for both purposes, as do 18% of those 75 and older.

Still, wide majorities of Republicans in all age groups favor legalizing marijuana for medical use. Even among Republicans 65 and older, just 17% say marijuana use should not be legal even for medical purposes.

While majorities of Democrats across all age groups support legalizing marijuana for medical and recreational use, older Democrats are less likely to say this. About half of Democrats ages 75 and older (51%) say marijuana should be legal for medical or recreational purposes; larger shares of younger Democrats say the same. Still, only 8% of Democrats 75 and older think marijuana should not be legalized even for medical use – similar to the share of all other Democrats who say this.

Note: Here are the questions used for this report, along with responses, and its methodology .

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Ted Van Green is a research analyst focusing on U.S. politics and policy at Pew Research Center .

9 facts about Americans and marijuana

Most americans favor legalizing marijuana for medical, recreational use, most americans now live in a legal marijuana state – and most have at least one dispensary in their county, clear majorities of black americans favor marijuana legalization, easing of criminal penalties, concern about drug addiction has declined in u.s., even in areas where fatal overdoses have risen the most, most popular.

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The Evidence—and Lack Thereof—About Cannabis

Research is still needed on cannabis’s risks and benefits. 

Lindsay Smith Rogers

Although the use and possession of cannabis is illegal under federal law, medicinal and recreational cannabis use has become increasingly widespread.

Thirty-eight states and Washington, D.C., have legalized medical cannabis, while 23 states and D.C. have legalized recreational use. Cannabis legalization has benefits, such as removing the product from the illegal market so it can be taxed and regulated, but science is still trying to catch up as social norms evolve and different products become available. 

In this Q&A, adapted from the August 25 episode of Public Health On Call , Lindsay Smith Rogers talks with Johannes Thrul, PhD, MS , associate professor of Mental Health , about cannabis as medicine, potential risks involved with its use, and what research is showing about its safety and efficacy. 

Do you think medicinal cannabis paved the way for legalization of recreational use?

The momentum has been clear for a few years now. California was the first to legalize it for medical reasons [in 1996]. Washington and Colorado were the first states to legalize recreational use back in 2012. You see one state after another changing their laws, and over time, you see a change in social norms. It's clear from the national surveys that people are becoming more and more in favor of cannabis legalization. That started with medical use, and has now continued into recreational use.

But there is a murky differentiation between medical and recreational cannabis. I think a lot of people are using cannabis to self-medicate. It's not like a medication you get prescribed for a very narrow symptom or a specific disease. Anyone with a medical cannabis prescription, or who meets the age limit for recreational cannabis, can purchase it. Then what they use it for is really all over the place—maybe because it makes them feel good, or because it helps them deal with certain symptoms, diseases, and disorders.

Does cannabis have viable medicinal uses?

The evidence is mixed at this point. There hasn’t been a lot of funding going into testing cannabis in a rigorous way. There is more evidence for certain indications than for others, like CBD for seizures—one of the first indications that cannabis was approved for. And THC has been used effectively for things like nausea and appetite for people with cancer.

There are other indications where the evidence is a lot more mixed. For example, pain—one of the main reasons that people report for using cannabis. When we talk to patients, they say cannabis improved their quality of life. In the big studies that have been done so far, there are some indications from animal models that cannabis might help [with pain]. When we look at human studies, it's very much a mixed bag. 

And, when we say cannabis, in a way it's a misnomer because cannabis is so many things. We have different cannabinoids and different concentrations of different cannabinoids. The main cannabinoids that are being studied are THC and CBD, but there are dozens of other minor cannabinoids and terpenes in cannabis products, all of varying concentrations. And then you also have a lot of different routes of administration available. You can smoke, vape, take edibles, use tinctures and topicals. When you think about the explosion of all of the different combinations of different products and different routes of administration, it tells you how complicated it gets to study this in a rigorous way. You almost need a randomized trial for every single one of those and then for every single indication.

What do we know about the risks of marijuana use?  

Cannabis use disorder is a legitimate disorder in the DSM. There are, unfortunately, a lot of people who develop a problematic use of cannabis. We know there are risks for mental health consequences. The evidence is probably the strongest that if you have a family history of psychosis or schizophrenia, using cannabis early in adolescence is not the best idea. We know cannabis can trigger psychotic symptoms and potentially longer lasting problems with psychosis and schizophrenia. 

It is hard to study, because you also don't know if people are medicating early negative symptoms of schizophrenia. They wouldn't necessarily have a diagnosis yet, but maybe cannabis helps them to deal with negative symptoms, and then they develop psychosis. There is also some evidence that there could be something going on with the impact of cannabis on the developing brain that could prime you to be at greater risk of using other substances later down the road, or finding the use of other substances more reinforcing. 

What benefits do you see to legalization?

When we look at the public health landscape and the effect of legislation, in this case legalization, one of the big benefits is taking cannabis out of the underground illegal market. Taking cannabis out of that particular space is a great idea. You're taking it out of the illegal market and giving it to legitimate businesses where there is going to be oversight and testing of products, so you know what you're getting. And these products undergo quality control and are labeled. Those labels so far are a bit variable, but at least we're getting there. If you're picking up cannabis at the street corner, you have no idea what's in it. 

And we know that drug laws in general have been used to criminalize communities of color and minorities. Legalizing cannabis [can help] reduce the overpolicing of these populations.

What big questions about cannabis would you most like to see answered?

We know there are certain, most-often-mentioned conditions that people are already using medical cannabis for: pain, insomnia, anxiety, and PTSD. We really need to improve the evidence base for those. I think clinical trials for different cannabis products for those conditions are warranted.

Another question is, now that the states are getting more tax revenue from cannabis sales, what are they doing with that money? If you look at tobacco legislation, for example, certain states have required that those funds get used for research on those particular issues. To me, that would be a very good use of the tax revenue that is now coming in. We know, for example, that there’s a lot more tax revenue now that Maryland has legalized recreational use. Maryland could really step up here and help provide some of that evidence.

Are there studies looking into the risks you mentioned?

Large national studies are done every year or every other year to collect data, so we already have a pretty good sense of the prevalence of cannabis use disorder. Obviously, we'll keep tracking that to see if those numbers increase, for example, in states that are legalizing. But, you wouldn't necessarily expect to see an uptick in cannabis use disorder a month after legalization. The evidence from states that have legalized it has not demonstrated that we might all of a sudden see an increase in psychosis or in cannabis use disorder. This happens slowly over time with a change in social norms and availability, and potentially also with a change in marketing. And, with increasing use of an addictive substance, you will see over time a potential increase in problematic use and then also an increase in use disorder.

If you're interested in seeing if cannabis is right for you, is this something you can talk to your doctor about?

I think your mileage may vary there with how much your doctor is comfortable and knows about it. It's still relatively fringe. That will very much depend on who you talk to. But I think as providers and professionals, everybody needs to learn more about this, because patients are going to ask no matter what.

Lindsay Smith Rogers, MA, is the producer of the Public Health On Call podcast , an editor for Expert Insights , and the director of content strategy for the Johns Hopkins Bloomberg School of Public Health.

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Should Marijuana Be Legal?

And the author alex berenson makes a case against pot..

With Ross Douthat, Michelle Goldberg and David Leonhardt

Listen and subscribe to our podcast from your mobile device:

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This week on “The Argument” podcast, the columnists talk pot. First, Michelle Goldberg presses former New York Times reporter Alex Berenson on his forthcoming book about the dangers of marijuana, “ Tell Your Children: The Truth About Marijuana, Mental Illness, and Violence .”

Then, the columnists debate which marijuana policy the country should pursue. Michelle argues the harms of criminalizing weed outweigh the harms of legalizing it. Ross Douthat worries about the broader social impacts of legalization and the growth of the cannabis industry. And David Leonhardt favors a middle path, one that forgoes harsh penalties for marijuana use without incentivizing more Americans to try it.

And finally, merry … Advent? Ross taps into his liturgical side to recommend a solution to the seasonal “Merry Christmas” versus “Happy Holidays” dilemma.

Background Reading:

Ross on marijuana and social libertarianism

David on marijuana’s health effects

Meet the Hosts

Ross douthat.

I’ve been an Op-Ed columnist since 2009, and I write about politics, religion, pop culture, sociology and the places where they all intersect. I’m a Catholic and a conservative, in that order, which means that I’m against abortion and critical of the sexual revolution, but I tend to agree with liberals that the Republican Party is too friendly to the rich. I was against Donald Trump in 2016 for reasons specific to Donald Trump, but in general I think the populist movements in Europe and America have legitimate grievances and I often prefer the populists to the “reasonable” elites. I’ve written books about Harvard, the G.O.P., American Christianity and Pope Francis; I’m working on one about decadence. Benedict XVI was my favorite pope. I review movies for National Review and have strong opinions about many prestige television shows. I have three small children, two girls and a boy, and I live in New Haven with my wife.

Michelle Goldberg

I’ve been an Op-Ed columnist at The New York Times since 2017, writing mainly about politics, ideology and gender. These days people on the right and the left both use “liberal” as an epithet, but that’s basically what I am, though the nightmare of Donald Trump’s presidency has radicalized me and pushed me leftward. I’ve written three books, including one, in 2006, about the danger of right-wing populism in its religious fundamentalist guise. (My other two were about the global battle over reproductive rights and, in a brief detour from politics, about an adventurous Russian émigré who helped bring yoga to the West.) I love to travel; a long time ago, after my husband and I eloped, we spent a year backpacking through Asia. Now we live in Brooklyn with our son and daughter.

David Leonhardt

I’ve worked at The Times since 1999 and have been an Op-Ed columnist since 2016. I caught the journalism bug a very long time ago — first as a little kid in the late 1970s who loved reading the Boston Globe sports section and later as a teenager working on my high school and college newspapers. I discovered that when my classmates and I put a complaint in print, for everyone to see, school administrators actually paid attention. I’ve since worked as a metro reporter at The Washington Post and a writer at BusinessWeek magazine. At The Times, I started as a reporter in the business section and have also been a Times Magazine staff writer, the Washington bureau chief and the founding editor of The Upshot.

My politics are left of center. But I’m also to the right of many Times readers. I think education reform has accomplished a lot. I think two-parent families are good for society. I think progressives should be realistic about the cultural conservatism that dominates much of this country. Most of all, however, I worry deeply about today’s Republican Party, which has become dangerously extreme. This country faces some huge challenges — inequality, climate change, the rise of China — and they’ll be very hard to solve without having both parties committed to the basic functioning of American democracy.

How do I listen?

Tune in on iTunes , Google Play , Spotify , Stitcher or wherever you listen to podcasts. Tell us what you think at [email protected]. Follow Michelle Goldberg ( @michelleinbklyn ), Ross Douthat ( @DouthatNYT ) and David Leonhardt ( @DLeonhardt ) on Twitter.

This week’s show is produced by Alex Laughlin for Transmitter Media, with help from Caitlin Pierce. Our executive producer is Gretta Cohn. We had help from Tyson Evans, Phoebe Lett and Ian Prasad Philbrick. Our theme is composed by Allison Leyton-Brown. Thank you to Kaiser Health News. Check out its podcast “What the Health.”

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Six policy lessons relevant to cannabis legalization

Chelsea l. shover.

Stanford University, Palo Alto, California

Keith Humphreys

Veterans Affairs Health Care System and Stanford University, Palo Alto, California

Background:

Cannabis (marijuana) has been legalized for recreational and/or medicinal use in many U.S. states, despite remaining a Schedule-I drug at the federal level. As legalization regimes are established in multiple countries, public health professionals should leverage decades of knowledge from other policy areas (e.g., alcohol and tobacco regulation) to inform cannabis policy.

Objectives:

Identify policy lessons from other more established policy areas that can inform cannabis policy in the U.S., Canada, and any other nations that legalize recreational cannabis.

Narrative review of policy and public health literature.

We identified six key lessons to guide cannabis policy. To avoid the harms of “a medical system only in name”, medical cannabis programs should either be regulated like medicine or combined with the recreational market. Capping potency of cannabis products can reduce the harms of the drug, including addiction. Pricing policies that promote public health may include minimum unit pricing or taxation by weight. Protecting science and public health from corporate interest can prevent the scenarios we have seen with soda and tobacco lobbies funding studies to report favorable results about their products. Legalizing states can go beyond reducing possession arrests (which can be accomplished without legalization) by expunging prior criminal records of cannabis-related convictions. Finally, facilitating rigorous research can differentiate truth from positive and negative hype about cannabis’ effects.

Conclusion:

Scientists and policymakers can learn from the successes and failures of alcohol and tobacco policy to regulate cannabis products, thereby mitigating old harms of cannabis prohibition while reducing new harms from legalization.

Introduction

The normative debate about whether governments should legalize medical and/or recreational cannabis (aka “marijuana”) remains high profile and vitriolic in multiple countries, and because of its political nature can at most be only partially informed by science ( 1 ). However, a less noticed but equally important discussion occurs beyond the click-worthy headlines and passionate op-eds: Given that medical and recreational cannabis legalization are already a reality in some countries (e.g., Canada, Uruguay) and over half of U.S. states and will likely become a reality in others, what lessons can we draw from other policy areas that will help regulatory systems maximize public health ( 2 , 3 )? Public health research can and should play a large role in this discussion particularly given the availability of decades of evidence on the impact and regulation of other potentially addictive or otherwise harmful consumables (e.g., alcohol, tobacco, prescription opioids, sodas, nutritional supplements) ( 4 , 5 ).

We write as scientists, policy analysts, and public health professionals, and make no effort in this paper to persuade anyone to vote for or against marijuana legalization. We hope that those who support legalization will find the foregoing discussion of value because they care about public health. After all, no one supports legalization hoping it will lead to more cannabis-induced auto accidents, for example. We hope that those who oppose cannabis legalization will also find our analysis of value because even when the overall policy framework is not to one’s liking, there are usually still ways of making it better (or at least less objectionable) including in ways that a legalization opponent would approve. Though many of our examples draw from the U.S. setting, we aim for recommendations that could apply in other countries considering or implementing cannabis legalization.

We recognize that efforts to address public health concerns regarding legal cannabis will meet with some political resistance, particularly in the corporate-friendly United States Cannabis industry players typically aim to maximize profits even it if harms public health. For their part, voters and advocacy groups often care about things other than public health (e.g., their views on personal freedom, their religious and cultural values). But the fact that a public health agenda under cannabis legalization will be difficult to achieve is not a reason to abandon it. Our six lessons are thus explicitly aspirational.

Although we believe the lessons presented here could be applied in many countries, we focus mainly on the United States both because we know it the best and because its cannabis regulation framework is unusually fluid due to the federal-state conflict in law, and the ongoing march of cannabis legalization across state after state (most recently, in November 2018 Michigan legalized recreational marijuana and Utah and Missouri legalized medical marijuana).. In the U.S., cannabis remains a Schedule I substance and illegal at the federal level, but memos issued during the previous presidential administration effectively left enforcement up to the states ( 6 ). A January 2018 memo from the current Department of Justice (DOJ) formally rescinded this policy, and at this writing it remains unclear whether or how the Trump administration will respond to cannabis legalization ( 7 ). Further complicating the legal landscape, the cannabis plant contains over 100 different cannabinoids, and there is presently one case where cannabinoids with different properties are subject to different regulations. Medication containing the non-psychoactive cannabidiol (CBD) and no more than 0.1% of the psychoactive constituent tetrahydrocannabinol (THC) were recently down-scheduled to Schedule V ( 8 ). All of this complexity, contradiction, and ferment makes it particularly important and opportune in the U.S. to inject public health concerns into the debate in the hopes of shaping the future.

1. Do not have a medical marijuana system that is not truly medical

Medicine has status, trust and privilege in society because of what it can accomplish and also because of how tightly it is regulated. Proponents of medical cannabis has attempted to gain similar status, trust and privilege, without the matching responsibilities of being carefully regulated. Indeed, if cannabis is indeed a medical drug, it is the least regulated medical drug in the U.S..

The experience of other unregulated quasi-medical industries, for example the patent medicines that thrived in the 19 th century and the supplements hawked on late night cable television, indicate that substantial harm can be done to the public by products that claim medicine’s mantle while evading its standards. The lesson for medical cannabis is that public health will be maximized if it either truly functions as medicine (e.g., with specified conditions, specific indications, and tight regulations), or, is folded into the recreational system.

To date, most “medical” cannabis has been sold with almost no medical oversight, with the role of physicians limited to writing a recommendation letter for patients. Physicians do not prescribe cannabis, nor do they provide it. Medical cannabis clients must take the physician recommendation letter to a separate dispensary, which is staffed by “budtenders” who typically do not have medical training. At the dispensary, clients choose from products of varying potency and content. Medical recommendation letters are often provided by physicians at clinics that solely provide medical cannabis recommendations, rather than primary care providers. Because the recommendation letter can sometimes be renewed over the phone or online without speaking to a clinician, medical oversight can easily be limited to the brief initial consultation. “Budtenders” can give any medical advice they wish, and this includes advice that is almost surely harmful to health, e.g., encouraging pregnant women to regularly smoke cannabis to reduce cramping ( 9 ).

Currently, a number of states operate separate medical and recreational cannabis markets (e.g., Colorado, Maine, Oregon) whereas others have combined the recreational and medical markets (e.g., Washington, California) ( 10 – 15 ). Acknowledging that something that is not regulated as medicine is not the same as medicine as commonly understood is good for public health. Combining programs may also streamline regulation and increase tax benefits to the state by preventing recreational users from entering the more lightly taxed medical system. Additionally, combining programs removes the incentive for youth to seek medical use to avoid higher age limits for recreational sales.

Medical and recreational use overlap, with most people who use medical cannabis also reporting recreational use ( 16 ). In a survey of a nationally representative panel of adults, only 10% of those who currently or ever used cannabis used it only for medical reasons ( 17 ). By way of comparison, consider how few people who take antibiotics, aspirin, or insulin to manage or cure disease would also use these drugs recreationally. Furthermore, with a few exceptions (e.g. CBD oils), the products available in medical and recreational outlets are the same. There is no reason the public should subsidize recreational drug use by making it tax-free, because lower prices feed over-consumption that harms public health (and also of course, imposes more costs on the public purse).

One concern about combining the two systems is that sick people will have to pay taxes on a medical product. But many products that can promote health are not tax-exempt (e.g. exercise equipment, cranberry juice for preventing bladder infections, over the counter medications in most states). As therapeutic uses for cannabis are identified with high-quality empirical data, relevant components or resulting medications can enter the medical system like any other drug, proceeding through FDA approval. As cannabinoid-derived drugs are approved, they can be covered by insurance or become available over the counter, where their potency and components will be regulated.

2. Protect science, regulation, and public health from corporate influence

When many people think of cannabis legalization, they envision a world where cannabis is sold by small operations owned by anti-corporate hippies who donate a portion of their profits to save the whales ( 18 ). In reality, legalization in the U.S. is leading to corporate cannabis run largely by hard-charging white guys in business suits who have MBAs and JDs and think of hippies with distaste if they think of them at all. The tobacco industry has been poised to capitalize on legal cannabis ( 19 ), as are the sugary beverage and alcohol industries ( 20 ). All scientists are aware of the potentially corrupting influence of industries in funding studies to support preferred conclusions and lobbying to promote industry’s business interests. For example, soda companies have long sponsored nutrition studies and legislation ( 21 ).

Protecting science and public health from corporate influence could take several forms. Full disclosure of cannabis industry-related conflicts of interest by researchers and journals should be standard ( 22 ). Robust non-corporate funding for cannabis research is also important, along the lines of California’s Tobacco Related Diseases Research Program which now funds proposals related to cannabis as well as tobacco.

Advertising regulations like those in place for tobacco products – e.g., advertising cannot target children, limits on where and when advertisements can be displayed or aired – may also be a key tool to promote public health. Currently, the industry in the U.S. complains that its advertising expenses are not tax deductible whereas those of the alcohol and tobacco industry are. The industry’s lobbyists are correct that this is an inconsistency, but from a public health viewpoint the best approach would be to subject alcohol and tobacco to the same restrictions rather than use public funds to subsidize sale of addictive products.

Evidence-informed public health education campaigns about cannabis are needed. Public health messages should take care not to exaggerate risks, lest they lose credibility in the face of the observation that many people do use cannabis without developing a use disorder or experiencing even the harms associated with over-consumption of alcohol. Ad campaigns similar to public health campaigns about alcohol – covering topics like getting help when use is out of control, abstaining during pregnancy and while trying to become pregnant, not using while driving, and not selling to minors – could promote public health.

Public health promoting regulations are more likely to be implemented if policymakers prevent the foxes from guarding the hen house. Multiple states give individuals from marijuana corporations seats on regulatory commissions, and do not require sufficient disclosure of marijuana industry-related conflicts of interest, for example when inviting “independent experts” to comment on developing legislation and regulations. The ballot initiative process is a particularly tempting opportunity to achieve regulatory capture, because industry players can potentially encode pro-profit, anti-public health, rules into the law for the long term. For this reason, even legislature members who oppose marijuana legalization might consider legislating their own framework when facing a corporate-written and funded legalization ballot initiative that seems likely to pass.

Last but most assuredly not least, non-corporate models should be considered by legalizing states and countries, as has been adopted in some Canadian provinces ( 5 , 23 ). For example, the state monopoly system used to sell alcohol in many U.S. states significantly reduces sales to youth and alcohol related harm ( 24 , 25 ). The same should be considered for cannabis, as should restricting the sale to non-profits and coops.

3. Cap the potency of cannabis products

Some drug policy analysts used to speak of the “Iron Law of Prohibition” which maintained that drugs become more potent over time because they are illegal. This is simply incorrect as tobacco, alcohol, and pharmaceuticals have all become substantially more potent since their development while being legal. Legality per se does nothing to limit potency unless there is a law that caps it.

Just as tobacco became more potent and more addictive in the 1900s– the same has happened with cannabis ( 26 , 27 ). Illegal cannabis smoked on college campuses in the 1970s had 3–5% THC, whereas legal cannabis sold in Washington State today averages 20% THC ( 28 ). Higher potency is concerning because of greater risk of adverse psychiatric effects and greater potential to transition light users into daily users and cannabis use disorders ( 29 – 31 ). For example, a study in the Netherlands found first-time drug treatment admissions for cannabis rose following increasing cannabis potency ( 32 ). If more potent cannabis is more addictive, increased availability post-legalization may increase the number of individuals who develop cannabis use disorder. Additionally, though cannabis poses essentially no fatal overdose risk, cannabis ingestion poses health threats to children, and this risk increases with increased potency. Increased potency can also magnify the indirect harms of cannabis intoxication, such as impaired driving and accidental injuries.

Because cannabis today has dramatically higher THC levels than in prior era, past research may understate health effects. Capping potency of cannabis products can limit the as yet unknown effects of more potent cannabis while the science can catch up to nature of modern products. Of course, cannabis is not just flowers and leaves: concentrates, oils, dabs, topicals, and products yet to be invented are likely to grow in popularity after legalization. States can mitigate these concerns by capping potency of cannabis products, just as they do certain classes of alcoholic beverages: To call something beer for example, requires abiding by certain limits to ethanol concentration ( 33 ). Similarly, cannabis oils or concentrates would reasonably have a higher potency limit per ounce than flowers—just as spirits can have a higher ethanol content than beer—but would still be restricted to a limited amount of THC per package. The limits recommended by California Department of Public Health – which include limiting THC content per package and limiting potency of inhaled products – are a good start ( 34 ). For oils and other smokeless cannabis products, the per-package limits would need to be set by regulatory bodies of scientists rather than industry, as discussed earlier. Banning smokeless cannabis products would likely result in increasing use of smoked cannabis and all of the attendant smoke-related health complication. Entirely banning high-potency products legal cannabis market may also have the unintended consequence of pushing consumers to the illicit market ( 35 ). Therefore, we do not at the present time advocate banning high-potency cannabis products like dabs, oils, or concentrates, but rather tailored and enforced regulations for labeling and packaging. In addition to capping potency, regulators have the opportunity to reduce harms of co-use of alcohol or tobacco with cannabis by explicitly banning products that combine cannabis and alcohol (as in, cannabinoids in alcohol) or cannabis and nicotine. Requiring every cannabis product sold for smoking or in smokable form to carry the message “Caution; cannabis smoke contains carcinogens” would communicate the risks of smoking specifically that may differ other cannabis products. Finally, regardless of what level of THC cap is in place, governments might consider setting taxes higher for high THC products. We explore other ways to use price setting to promote public health in the next section.

4. Price may be the most effective lever to promote public health

There’s an old saw that “Addicts will do anything to get their fix” but experimental and epidemiological research conducted in dozens of countries has established the opposite: Drug use is responsive to price, even for the heaviest drug users ( 36 ).

This observation is critical for understanding cannabis legalization because nothing the government does raises the price of the drug as high as does prohibition, which poses enormous costs on business ( 37 ). This is why the removal of cannabis prohibition has produced a price collapse in state after state, including a 70% drop of wholesale prices in 4 years in Colorado and even steeper drops in Oregon and Washington ( 38 , 39 ). Cannabis is called “weed” because it is very easy to grow, and easy to grow, legal crops in America (e.g., wheat) are very cheap. Legal prices are falling about 1% every 2–4 weeks and their natural bottom could be as low as a nickel per joint, such that cannabis becomes like beer nuts – a complimentary offering by restaurants and bars.

Health taxes have effectively reduced consumption of tobacco, alcohol, and sugar-sweetened beverages ( 36 , 40 ). Raising taxes on alcohol has also been demonstrated to reduce serious harms including death and injury due to motor vehicle accidents ( 41 , 42 ).

Sales of retail cannabis have typically been subject to sales and excise tax, but rates vary significantly between states ( 40 ). Because these taxes are generally set as a percent of price and the price is rapidly collapsing, the ability of such taxes to raise revenue and deter excessive use is thus waning almost every day ( 38 , 39 ). A more effective alternative is to tax the raw cannabis (i.e., flowers, leaves) by weight as California has always done and Maine has just begun to do ( 43 ). This raises fear of potency soaring as producers try to pack more THC in every ounce, but this can be countered by implementing potency caps, as discussed earlier. In the case of products that contain cannabis and other ingredients – e.g., brownies, lemonade, lattes – the amount of cannabis that can be included (in terms of potency) would be set by potency caps, and the tax could be based on the weight or unit of cannabis, not the entire product.

Minimum unit pricing of cannabis also merits serious consideration. This approach is used for alcohol in British Columbia and was also recently implemented in Scotland ( 44 ). It is not a tax, but rather a floor price below which a product cannot be sold. Implementing it for alcohol reduces emergency room admissions, alcohol-related arrests and injuries, and deaths ( 45 ). Public health benefits would also be expected from implementing such a minimum unit pricing policy for cannabis.

5. Look beyond reducing marijuana possession arrests

Wanting to reduce marijuana possession arrests is a weak rationale for legalization. Decriminalizing marijuana possession in California for example dropped both adult and adolescent possession arrests by over 60% in just 12 months ( 46 ). Arrests can be dramatically curtailed without creating a corporate industry that sells marijuana.

In contrast, legalization is an excellent opportunity to reduce the damage of prior criminal penalties by expunging the records of individuals arrested for possession as well as low-level dealing. This group is disproportionately poor and minority, and their arrest record limits their ability to obtain housing, work, and education ( 47 ). It also keeps people with expertise out of the emerging and overwhelmingly white-dominated, cannabis industry.

Currently, the process to get records updated in California requires an individual to hire a lawyer to get a possession record expunged or a felony for selling downgraded to a misdemeanor, but a bill introduced in the state senate would automate this process ( 48 ). One way to fund this effort in California as well as in other legalization states would be to designate some tax revenue from retail cannabis sales for this purpose.

6. Facilitate rigorous research

“More research is needed” has become a tired academic cliché, but it’s nonetheless applicable to cannabis legalization. Debate about the health benefits and risks of all manner of products is a commonplace of modern life and is certainly the case with cannabis. In political debates, the drug is characterized as extremely dangerous by some activists and as harmless – indeed extraordinarily therapeutic – by others. There is evidence for some harms and some benefits, although in neither case does the limited evidence available support more extreme assessments in either direction. In terms of benefit, a 2017 report by The National Academies of Sciences, Engineering, and Medicine concluded that there is substantial evidence that cannabis is an effective treatment for some chronic pain conditions in adults, and spasticity symptoms in multiple sclerosis, as well as conclusive evidence of efficacy in treating nausea and vomiting induced by chemotherapy ( 49 ). Other reviews have been more cautious in their conclusions, noting that the research base is old, includes many comparisons of cannabis to drugs which are no longer used because more effective ones have become available, and have small sample sizes ( 50 ).

In terms of harms, fairly rigorous quasi-experimental work indicates that greater access to cannabis leads to lower educational achievement ( 51 ). U.S. prevalence estimates of cannabis use disorder among people reporting past-year cannabis use vary in recent nationally representative surveys, with estimates ranging from 12% in the 2013 National Survey on Drug Use and Health to 31% in the 2012–13 National Epidemiologic Survey of Alcohol and Related Conditions ( 29 , 52 ). But whether cannabis use disorder is becoming more of less prevalent is not clear ( 29 , 52 ). On the one hand the proportion of cannabis users who used the drug every day or nearly every day is increasing sharply ( 53 ), but on the other hand with legalization and normalization, some of the negative effects of frequent cannabis use may be waning (e.g., problems with employers, conflicts with family members who disapprove of cannabis).

The obvious lesson to draw from all other putatively medical products as well as other addictive drugs is that empirical claims about health or social effects and should be investigated empirically. The U.S. has a careful system for studying and approving medications in place and it should be used for cannabis-related medicines as well. Only through rigorous research can effective therapies derived from cannabis be approved and regulated by the Food and Drug Administration (FDA). Properties should be investigated in controlled studies and resulting therapies should proceed through FDA approval process as have one CBD-derived medication and two medications derived from synthetic cannabinoids ( 54 ). It should be noted that the FDA approval process may be particularly difficult for a botanical cannabis product (as opposed to a chemical extract), due to variation in concentration of cannabinoids between plants. However, the FDA currently regulates several plant-matter botanical drug products in its over-the-counter review (e.g., psyllium, cascara, senna) and has approved two botanical products for marketing as prescription drugs ( 55 ).

One regulatory reform that has been considered in Congress is to alter the Controlled Substances Act (CSA) such that Schedule I drugs with therapeutic potential could be more easily studied ( 56 ). Creating a “Schedule I-R” would allow researchers and regulators to treat cannabis and its addictive constituent tetrahydrocannabinol (THC) as a lower-schedule substance when obtained for the purposes of advancing science ( 8 ). The recent downscheduling of a CBD extract formulation (Epidiolex) is an important step, but the rescheduling is currently limited to drugs that have already been approved by the FDA: “As further indicated, any material, compound, mixture, or preparation other than Epidiolex that falls within the CSA definition of marijuana set forth in 21 U.S.C. 802( 16 ), including any non-FDA-approved CBD extract that falls within such definition, remains a schedule I controlled substance under the CSA.” ( 8 ). Establishing a Schedule I-R would facilitate research on other cannabis products, other cannabinoids, and even other CBD-based formulations, all of which are currently still Schedule I ( 8 ).

A second reform that would improve the quantity and quality of cannabis research is to allow more farms to grow cannabis for research purposes rather than having only the federal monopoly provider in Mississipi. It seems bizarre for example that states can operate medical cannabis programs that give the drug to sick patients, but are not allowed to run medical cannabis research programs. In 2016 the Drug Enforcement Agency expanded the number of authorized manufacturers of cannabis for National Institute on Drug Abuse-funded research, but none of the organizations that applied for a license has been granted one by the Trump Administration ( 54 ).

For findings to be relevant, and to determine how differing modes of use or potency may modify health effects, at least some research on cannabis must be conducted on consumer cannabis products. Combustible may still be most common mode of use ( 17 ), but as retail markets expand researchers need to evaluate edible, vaporized, topical, and other smokeless products.

Currently, one topic that is especially relevant and contentious is whether cannabis legalization can decrease use of opioids. Some evidence suggests that medical cannabis can be opioid sparing ( 57 , 58 ), but studies have been limited by small sample size (e.g., Abrams’ clinical trial of 21 patients) or self-reported exposure and outcomes (e.g., Boenkhe’s was an online survey of clients of a medical cannabis dispensary). A systematic review found some pre-clinical evidence of “opioid sparing” effects, but clinical evidence was lacking ( 59 ). Epidemiological studies show state-level correlations between cannabis legalization and lower opioid overdoses, but such ecological studies have serious, well-known, flaws ( 60 ). Even individual-level studies showing that cannabis use and opioid use are positively correlated should not be taken as proof of a causal relationship ( 61 ). Yet medical cannabis use is associated with higher rates of prescription drug use and misuse ( 62 ). Furthermore, a recent four-year prospective study in Australia found no evidence that cannabis use improved patient outcomes in patients prescribed opioids for chronic, non-cancer pain ( 63 ). Clinical trials, and large-scale records-based studies with data at an individual level are warranted.

Change in other non-cannabis substance use after cannabis legalization could also be positive or negative. Some studies suggest that youth smoke cannabis as a precursor to tobacco – this order of events could potentially reverse advances in tobacco control measures ( 64 , 65 ). Broader availability of cannabis could theoretically reduce alcohol-related harms if alcohol and cannabis are substitutes. Conversely, it’s possible that legalized cannabis will augment societal harms caused by alcohol use if the two drugs are complements– this line of research needs to be continued. Further research on the relationship between cannabis use and use of tobacco, alcohol, and other substances can clarify this. The urgency of policy research on new cannabis laws should be balanced with the need to gather enough data for careful assessment. There is a risk policy evaluations conducted too soon after cannabis legalization will fail to detect midterm and longer term adverse outcomes.

Conclusions

In summary, cannabis legalization may have positive and negative impacts on public health, and policies should aim to maximize the former and minimize the latter. There are many other important topics we have not covered – e.g., public consumption, strategies to reduce and detect impaired driving, rules on pesticides, fraud detection – and the future will likely raise other concerns which no one is aware of at this moment. We recommend continued, rigorous research, by scientists who report results in an objective and balanced manner, free from corporate influence. With the benefit of decades of observation about policy successes and failures in regulating other drugs, policymakers can promote policies that rectify harms of cannabis prohibition, and policies that strive to minimize harms of legalization. Public health professionals and scientists have a role to play in conducting rigorous research, disseminating results in an objective and balanced manner, and contributing to making evidence-informed policy.

Acknowledgments

Authors’ Note: Chelsea L. Shover was supported by the National Institute on Drug Abuse of the National Institutes of Health under award number T32 DA035165 . Research reported in this publication was supported by the National Institute The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Keith Humphreys was supported by a Senior Career Research Scientist Award from the Veterans Health Administration, Stanford Neurosciences Institute, and the Esther Ting Memorial Professorship at Stanford University. Any views expressed are the responsibility of the authors and do not necessarily reflect policy positions of their employers. The authors report no relevant financial conflicts.

Financial disclosures and funding information: The authors report no conflicts of interest. The authors were supported by the National Institute on Drug Abuse, the Veterans Health Services Research and Development Service, and [blinded] Neurosciences Institute. Research reported in this publication was supported by the National Institute On Drug Abuse of the National Institutes of Health under Award Number [blinded]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Contributor Information

Chelsea L. Shover, Stanford University, Palo Alto, California.

Keith Humphreys, Veterans Affairs Health Care System and Stanford University, Palo Alto, California.