Health, harm and the design of a market: what the evidence asks of policy

The earlier articles in this series asked one narrow question of each legal regime: judged against its own stated aims, what did it achieve? We separated the different kinds of regime that the words "legal" and "illegal" blur together, then examined the record of criminal prohibition, the reform models that stop short of a commercial industry and the commercial markets of North America. This final article turns to the question underneath all of them: what does cannabis do to health, and does the answer depend on the law?

The critical review on which this series is based makes a claim that may surprise both camps. The health evidence, it argues, is best read independently of legal status, because the main drivers of harm are the pattern of use, the potency of the product and the age at which people start. Legal regimes matter to health mainly through their effects on those three variables. Below we walk through that evidence, then the regulatory tools and treaties, and end with the review's scorecard and conclusions.

In the United Kingdom, cultivation and possession of cannabis remain criminal offences, and growing the plant needs a Home Office licence even for patients with a prescription. This article is analytical and gives no guidance on obtaining, growing or using cannabis.

Reading health evidence apart from the law

Health outcomes are not a simple verdict on policy, for reasons set out in the first article. Use was already rising in many countries before reform. People report more use once it is legal. The product changed over the period, so "use" in the 1970s and "use" today are exposures to rather different substances (Freeman et al., 2021). And most commercial markets are less than a decade old, so harms that build up over years may not yet be visible.

These hazards work in both directions. They weaken the claim that reform has been harmless, and equally the claim that it has been a disaster.

Psychosis

What the strongest study found

The review describes the association between heavy cannabis use and psychotic disorder as one of the most robust findings in the field. Its central evidence is the EU-GEI study (Di Forti et al., 2019).

EU-GEI is a case-control study. Rather than following a large population for years to see who falls ill, researchers start from the outcome: they recruit people who already have the illness (cases) and comparable people who do not (controls), then compare their past exposures. The study recruited 901 patients with first-episode psychosis and 1,237 population controls across 11 sites in Europe and Brazil. After adjustment, daily users were about three times as likely as never-users to have a psychotic disorder, and daily users of high-potency cannabis (THC of 10% or more) about five times as likely (Di Forti et al., 2019).

Adjustment means statistically accounting for other differences between cases and controls that might explain the link. In case-control designs, "times as likely" figures are usually odds ratios: the odds of exposure among cases divided by the odds among controls. A ratio of 1 means no difference; for an uncommon illness, the ratio is a reasonable guide to how much an exposure raises risk. Each estimate also comes with a confidence interval, the range of values compatible with the data; a narrow interval signals precision, a wide one uncertainty. Here we give the central figures as the review reports them.

The authors went further. Assuming causality, they estimated that 12.2% of first-episode psychosis cases across the sites would be prevented if high-potency cannabis were unavailable, rising to 30.3% in London and 50.3% in Amsterdam. Sites where high-potency products were widely available also had higher incidence of psychotic disorder (Di Forti et al., 2019). Such estimates depend on how common the exposure is, hence the variation between cities.

Two cautions

The review attaches two cautions. First, a case-control study cannot by itself prove causation: some unmeasured factor might drive both cannabis use and illness, and the prevention figures assume causality. The authors draw on wider evidence to support a causal link, but the study alone is not proof.

Second, and more important for this series, the high-risk products were widespread in London, under prohibition, as well as in Amsterdam, under tolerated retail. Psychosis risk follows potency and frequency, and neither regime controlled them.

Each side can draw on this: advocates of control on a robust association that strengthens with potency and frequency, reformers on the fact that the most dangerous products flourished under a prohibition that could not regulate what was sold.

Canada adds a further piece. In an Ontario cohort of more than 13.5 million people, the share of new schizophrenia cases associated with cannabis use disorder rose from 3.7% before legalisation to 10.3% after it (Myran et al., 2025). The authors stress that the rise was steady over the whole period, with no clear acceleration at the point of policy change, so it may reflect long-run increases in potency and heavy use more than legalisation as such. The review's verdict on the claim that legalisation causes psychosis: contested; the risk is real but not specific to legal regimes.

Dependence

The review calls cannabis use disorder, the clinical term for dependence and problematic use, the most common serious harm. About 42% of drug use disorder cases worldwide are attributed to cannabis (UNODC, 2025).

Potency matters here too. A systematic review, which searches the literature by a predefined protocol and assesses every eligible study rather than a convenient selection, found that higher-potency cannabis was associated with a higher risk of cannabis use disorder than lower-potency products, with one of the strongest included studies reporting roughly four-fold higher odds (Petrilli et al., 2022).

Frequency of use, the review notes, is the strongest predictor of dependence. That is why rising daily use in commercial markets is a serious concern. In 2022 an estimated 17.7 million Americans used cannabis daily or near-daily, more than the 14.7 million who drank alcohol that often; Caulkins notes that greater willingness to report use explains part of the long-run rise, but not all of it (Caulkins, 2024).

Neither camp is comforted: prohibition did not prevent this burden, and commercial markets have seen more of the frequent use that best predicts dependence.

Adolescents, driving and children

The US National Academies of Sciences, Engineering, and Medicine, reviewing the health literature in 2017 and grading findings by strength of evidence, found that starting cannabis use at a younger age is associated with a greater likelihood of later problem use. It also found substantial evidence of a statistical association between cannabis use and increased risk of motor vehicle crashes (National Academies of Sciences, Engineering, and Medicine, 2017). Both are associations, not proof of cause.

On adolescents, the policy evidence is more reassuring than many predicted: the best quasi-experimental studies from the United States and Uruguay find no average increase in youth use after legalisation (Anderson et al., 2019; Laqueur et al., 2020), though follow-up remains short. On driving, Canada's monitoring survey reports that driving after cannabis use fell from 27% of users in 2018 to 18% in 2024 (Health Canada, 2024), a self-reported figure subject to the usual reporting caveats.

One harm stands apart. Accidental poisoning of young children scarcely existed under prohibition and grew with legal edible products. In the United States, edible cannabis exposures among children under six reported to poison centres rose from 207 in 2017 to 3,054 in 2021, an increase of 1,375% (Tweet, Nemanich and Wahl, 2023). In Ontario, emergency department visits for cannabis poisoning in children under ten rose about nine-fold after legalisation; the largest increase followed the legal sale of commercial edibles, after which nearly 10% of all paediatric poisoning visits involved cannabis (Myran et al., 2022).

The Ontario study used an interrupted time series: tracking an outcome over many years and looking for a break in its level or trend when a policy changes. When the break coincides with a specific change, here the arrival of edibles rather than legalisation itself, the case for a link is much stronger. The review calls child poisoning one of the clearest cases of harm caused by a specific design choice rather than by legalisation as such.

Relative harm

How harmful is cannabis compared with other drugs? The best-known attempt to answer used multicriteria decision analysis. Because different harms have no common scale, experts score each drug on each criterion and weight the criteria so the scores can be combined.

The Independent Scientific Committee on Drugs scored 20 drugs on 16 criteria of harm to users and to others. Alcohol scored highest overall (72 out of 100), heroin 55 and crack cocaine 54, while cannabis scored 20. The authors noted that their ranking correlated poorly with the UK classification system (Nutt, King and Phillips, 2010).

The method has been criticised on two grounds. Its results depend on the judgement and weighting of a small expert panel, so different weights could shift the ranking. And it scores harms as they occurred under existing laws, which conflates the harms of a drug with those of its policy. Even so, the review concludes, the central finding, that the legal status of drugs bears little relation to their relative harm, has not been seriously overturned. A score of 20 is, of course, lower than alcohol's, not zero.

Therapeutic evidence

The National Academies (2017) found conclusive or substantial evidence that cannabis or cannabinoids are effective for chronic pain in adults, for chemotherapy-induced nausea and vomiting (oral cannabinoids) and for patient-reported spasticity in multiple sclerosis.

The strongest single result comes from a randomised controlled trial in children with Dravet syndrome, a severe childhood epilepsy. Patients were assigned by chance to purified cannabidiol or placebo, so that the groups differed on average only in treatment. Median monthly convulsive seizures fell from 12.4 to 5.9 on cannabidiol, against a change from 14.9 to 14.1 on placebo (Devinsky et al., 2017). The median is the middle value when results are ranked, less distorted than an average by a few extreme cases. The trial led to US Food and Drug Administration approval of Epidiolex in 2018.

For most other conditions marketed by private clinics, the review says, the evidence remains limited or absent. That matters in the UK, where almost all lawful prescribing is private, with an estimated 45,000 patients being treated by 2024 (Pharmaceutical Journal, 2024). Prohibition bears part of the blame for the thin evidence: the National Academies concluded that regulatory barriers, including the classification of cannabis in Schedule I in the United States, had impeded research on both harmful and therapeutic effects (National Academies of Sciences, Engineering, and Medicine, 2017).

What the health evidence implies

The evidence, the review concludes, does not support the claim that cannabis is harmless, nor the claim that prohibition protected health. Prohibition coincided with rising potency it could not regulate and blocked research into therapeutic benefits. Commercial legalisation has added new harms, notably heavier adult use and child poisonings, that follow from how products are designed and sold. What links both sets of findings, the review argues, is how the product is regulated, not whether it is legal in the abstract.

The regulatory toolkit

A genuine trade-off

In a commercial market the most profitable customers are the heaviest users (see the previous article). Kilmer (2017) argues that this gives a for-profit industry incentives similar to those of alcohol and tobacco firms: to increase frequent use, lower prices and lobby against restrictions. Non-commercial models avoid that pressure but have under-supplied the market: Uruguay's state model and Germany's associations left room for grey and illicit sellers (Queirolo et al., 2024; EKOCAN, 2026). Design therefore faces a real trade-off between displacing criminal markets and avoiding the promotion of heavy use.

Five levers

The reform literature identifies levers that sit between prohibition and an open market (Room et al., 2010; Rolles and Murkin, 2016):

The right-hand column is our reading, following the review's policy implications, not a claim that each lever has been shown to work: the review lists evaluating potency caps and THC-based taxation among its most urgent research needs.

Uruguay bans advertising and caps potency. Licensed US retailers check identification, which the authors of a large study of US high-school students suggest may make them harder for teenagers to buy from than illicit dealers (Anderson et al., 2021). The review's point is that these choices, not the legal label, determine how a market behaves. Two regimes can both be called "legal" and yet, with weak controls in one and strong controls in the other, be different policies with different outcomes.

Why prohibition cannot use them

This is also the review's strongest health argument against prohibition. Every lever needs a lawful supply chain to act on. Under prohibition the THC content of herbal cannabis rose by 0.29 percentage points a year from 1970 to 2017 (Freeman et al., 2021), and prohibition was structurally unable to address it. Yet legal markets have continued, and sometimes accelerated, the potency trend through concentrates and high-THC extracts. A lever that exists is not one that is used.

Treaty tensions

The 1961 Single Convention on Narcotic Drugs restricts cannabis to medical and scientific purposes (United Nations, 1961), so countries that have legalised non-medical use are in tension with it. The International Narcotics Control Board, which oversees the treaties, has repeatedly stated that Uruguay's and Canada's laws are inconsistent with treaty obligations.

The system has moved only so far. In December 2020 the UN Commission on Narcotic Drugs removed cannabis from Schedule IV of the 1961 Convention, its most restrictive category, while keeping it in Schedule I; this changed its scheduling but did not authorise non-medical markets (UNODC, 2020). In April 2026 the United States moved FDA-approved cannabis products and state-licensed medical marijuana into Schedule III, while non-medical marijuana remains in Schedule I (Drug Enforcement Administration, 2026). Both changes acknowledge medical value without endorsing non-medical legalisation. The international regime is therefore increasingly out of step with national practice, a gap that legal scholars and reform states have not yet resolved (Bewley-Taylor, Blickman and Jelsma, 2014).

Weighing the claims of both camps

The scorecard

Both literatures, the review observes, have selected evidence to suit their conclusions. Its table, reproduced as given, sets each side's claims against the evidence.

Neither side comes out clean. Prohibitionists lose on keeping use low and on the predicted surge; reformers lose on heavy adult use, child poisonings and eliminating the illicit market. The qualifications in the right-hand column matter as much as the verdicts.

The adolescent verdicts rest on difference-in-differences designs, which compare the change where policy changed with the change in similar places where it did not, and on synthetic control, which builds a comparison from a weighted blend of places with matching earlier trends (Laqueur et al., 2020). Both estimate what would have happened without reform, imperfectly when reforming places differ systematically from the rest.

Three distinctions the debate collapses

The review argues that public debate goes wrong mainly by collapsing three distinctions:

1. Users versus markets. The case for removing criminal penalties from users is considerably stronger than the case for any particular kind of legal market. Decriminalisation addresses the costs of enforcement without creating commercial incentives.
2. Adolescents versus adults. The fear that legalisation would harm teenagers has largely not materialised. The more serious and better-evidenced harm lies in heavier use among adults.
3. Legal status versus product design. Many of the worst outcomes, including rising potency and child poisonings, followed from what was sold rather than from whether selling was legal.

What the review concludes

Five conclusions

1. Criminal prohibition failed on its own terms. It did not stop cannabis becoming the world's most widely used illicit drug, could not regulate a steady rise in potency, left supply to criminal markets, and imposed costs through arrests, criminal records and stop-and-search that fell disproportionately on Black and minority communities. On a proportionality test, the review finds the criminalisation of individual users very difficult to justify.
2. Removing criminal penalties from users is the best-supported reform. Evidence from Portugal, the Netherlands and the 2024 German reform consistently shows large falls in criminal justice involvement without major increases in use. The review calls this the most robust conclusion in the literature.
3. The feared surge in adolescent use has not materialised, though follow-up remains short.
4. Commercial legalisation carries real costs among adults and children. Daily use, cannabis use disorder and child poisonings have risen in commercial markets. These harms are concentrated among a minority of heavy users, who are also the industry's most valuable customers.
5. Regulatory design matters more than legal status. Most good and bad outcomes after reform trace back to choices about potency, product form, price, marketing and ownership. The policy question, the review concludes, is no longer whether cannabis should be legal or illegal, but how its supply should be governed.

Implications for policy

From these conclusions the review sketches a model that neither restores criminal prohibition nor replicates the most commercial US markets: decriminalisation of possession for personal use; legal supply sufficient to compete with illicit sellers; limits on THC content and on edible products attractive to children; taxation linked to potency; strict marketing restrictions; and public or non-profit control of at least part of the supply chain. Each element has some empirical support, but no jurisdiction has yet combined all of them, so the model is an inference from scattered evidence rather than a tested package.

For the United Kingdom, the review concludes that the evidence suggests three immediate priorities that do not require full legalisation:

1. ending the criminalisation of personal possession;
2. reviewing the use of the smell of cannabis as grounds for stop-and-search;
3. reforming the medical scheme so that access does not depend on ability to pay.

On the second, the Independent Office for Police Conduct recommended in 2022 that the Home Office review what counts as reasonable grounds for suspicion of cannabis possession, including the smell of cannabis (IOPC, 2022). The review argues that any of the three would remain consistent with the international conventions. These are the review's conclusions, reported as analysis, not a campaign. The review stresses that home cultivation remains illegal under current UK law and that none of its conclusions should be read as guidance to act outside it.

A research agenda

The review's most urgent research needs are long-term cohort studies of psychosis and dependence in legal markets; direct comparisons of commercial and non-commercial models; evaluation of potency caps and THC-based taxation; studies of illicit market displacement using wastewater and seizure data as well as surveys; and rigorous trials of cannabinoid medicines for the many conditions currently treated on weak evidence. It singles out Germany's final evaluation (due 2028) and the Dutch controlled supply experiment, whose results were not yet available, because they test non-US models in European settings close to the UK.

What we know, and what we don't

The review is open about its limits. Commercial markets are young, and outcomes that depend on cumulative exposure may not yet be visible. Self-reported use is sensitive to changes in stigma. Jurisdictions that legalised were not randomly chosen; they tended to have more liberal attitudes and rising use before reform. Much of the best evidence comes from North America and may not transfer to the UK, with its different illicit market, policing culture and health system. And the review is narrative, not systematic, so it may underweight non-English research.

Some findings are firm: heavy use of high-potency cannabis is strongly associated with psychosis and dependence whatever the law, legal edibles have harmed young children, and enforcement of prohibition fell unequally. Others remain open: whether commercial markets will raise rates of psychosis over decades, how much of the rise in adult daily use is real rather than more honest reporting, and which mix of regulatory tools best balances market displacement against the promotion of heavy use. On Germany and the Netherlands, conclusions remain provisional.

The series in one view

Read together, the five articles trace a single argument. The first showed that a simple split between legal and illegal hides a range of distinct regimes, and set out how to weigh evidence about them. The second judged prohibition against its own aims and found a deterrent effect too small to meet them, bought at a high and unequal cost. The third looked at the Netherlands, Portugal, Uruguay and Germany, where decriminalising users proved the best-supported change but over-restricted supply left room for informal markets. The fourth found that commercial markets in the United States and Canada largely spared adolescents but intensified heavy use among adults, and that the UK's medical-only route favours those who can pay. This one has shown the health evidence pointing the same way: what matters most is what is sold, how strong it is, how it is marketed and who profits.

A closing remark

The review ends on a historical note: the history of cannabis policy is a history of laws running ahead of, or against, the evidence. In 1894, 1968 and 1972, official inquiries reached more moderate conclusions than the laws that followed them; the first two, the Indian Hemp Drugs Commission and the Wootton Report, appear in our history series (Advisory Committee on Drug Dependence, 1968; Mills, 2003). The current evidence, the review suggests, offers a chance to avoid repeating that pattern in the opposite direction: by replacing prohibition not with an unregulated market, but with regulation designed around what is now known about harm.

This article is based on the critical review it expands; figures are reported as that review gives them and were not re-checked against every original study.

Sources

ACLU (American Civil Liberties Union) (2020) A Tale of Two Countries: Racially Targeted Arrests in the Era of Marijuana Reform. New York: ACLU. Available at: https://www.aclu.org/publications/tale-two-countries-racially-targeted-arrests-era-marijuana-reform.

Advisory Committee on Drug Dependence (1968) Cannabis (the Wootton Report). London: HMSO.

Anderson, D.M., Hansen, B., Rees, D.I. and Sabia, J.J. (2019) 'Association of marijuana laws with teen marijuana use: new estimates from the Youth Risk Behavior Surveys', JAMA Pediatrics, 173(9), pp. 879–881. doi:10.1001/jamapediatrics.2019.1720.

Anderson, D.M., Rees, D.I., Sabia, J.J. and Safford, S. (2021) 'Association of marijuana legalization with marijuana use among US high school students, 1993–2019', JAMA Network Open, 4(9), e2124638. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC8424481.

Bewley-Taylor, D., Blickman, T. and Jelsma, M. (2014) The Rise and Decline of Cannabis Prohibition: The History of Cannabis in the UN Drug Control System and Options for Reform. Amsterdam and Swansea: Transnational Institute and Global Drug Policy Observatory.

Caulkins, J.P. (2024) 'Changes in self-reported cannabis use in the United States from 1979 to 2022', Addiction. doi:10.1111/add.16519.

Cerdá, M., Mauro, C., Hamilton, A., Levy, N.S., Santaella-Tenorio, J., Hasin, D., Wall, M.M., Keyes, K.M. and Martins, S.S. (2020) 'Association between recreational marijuana legalization in the United States and changes in marijuana use and cannabis use disorder from 2008 to 2016', JAMA Psychiatry, 77(2), pp. 165–171. doi:10.1001/jamapsychiatry.2019.3254.

Degenhardt, L., Chiu, W.T., Sampson, N., Kessler, R.C., Anthony, J.C. et al. (2008) 'Toward a global view of alcohol, tobacco, cannabis, and cocaine use: findings from the WHO World Mental Health Surveys', PLoS Medicine, 5(7), e141. doi:10.1371/journal.pmed.0050141.

Devinsky, O., Cross, J.H., Laux, L., Marsh, E., Miller, I., Nabbout, R., Scheffer, I.E., Thiele, E.A. and Wright, S. (2017) 'Trial of cannabidiol for drug-resistant seizures in the Dravet syndrome', New England Journal of Medicine, 376(21), pp. 2011–2020. doi:10.1056/NEJMoa1611618.

Di Forti, M., Quattrone, D., Freeman, T.P., Tripoli, G., Gayer-Anderson, C., Quigley, H. et al. (2019) 'The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study', The Lancet Psychiatry, 6(5), pp. 427–436. doi:10.1016/S2215-0366(19)30048-3.

Drug Enforcement Administration (2026) 'Schedules of Controlled Substances: Rescheduling of Food and Drug Administration approved products containing marijuana from Schedule I to Schedule III', Federal Register, 91 FR 22714, 28 April 2026.

Eastwood, N., Shiner, M. and Bear, D. (2013) The Numbers in Black and White: Ethnic Disparities in the Policing and Prosecution of Drug Offences in England and Wales. London: Release.

EKOCAN (2026) Evaluation des Konsumcannabisgesetzes (EKOCAN): 2. Zwischenbericht, 1 April 2026. Hamburg, Düsseldorf and Tübingen: EKOCAN consortium. Available at: https://www.uke.de/landingpage/ekocan/.

Freeman, T.P., Craft, S., Wilson, J., Stylianou, S., ElSohly, M., Di Forti, M. and Lynskey, M.T. (2021) 'Changes in delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) concentrations in cannabis over time: systematic review and meta-analysis', Addiction, 116(5), pp. 1000–1010. doi:10.1111/add.15253.

Health Canada (2024) Canadian Cannabis Survey 2024: Summary. Ottawa: Government of Canada. Available at: https://health-infobase.canada.ca/cannabis/.

Hughes, C.E. and Stevens, A. (2010) 'What can we learn from the Portuguese decriminalization of illicit drugs?', British Journal of Criminology, 50(6), pp. 999–1022. doi:10.1093/bjc/azq038.

IOPC (Independent Office for Police Conduct) (2022) National Stop and Search Learning Report. London: IOPC.

Kilmer, B. (2017) 'Recreational cannabis — minimizing the health risks from legalization', New England Journal of Medicine, 376(8), pp. 705–707. doi:10.1056/NEJMp1614783.

Laqueur, H., Rivera-Aguirre, A., Shev, A., Castillo-Carniglia, A., Rudolph, K.E., Ramirez, J., Martins, S.S. and Cerdá, M. (2020) 'The impact of cannabis legalization in Uruguay on adolescent cannabis use', International Journal of Drug Policy, 80, 102748. doi:10.1016/j.drugpo.2020.102748.

MacCoun, R. and Reuter, P. (2001) 'Evaluating alternative cannabis regimes', British Journal of Psychiatry, 178(2), pp. 123–128. doi:10.1192/bjp.178.2.123.

Mills, J.H. (2003) Cannabis Britannica: Empire, Trade, and Prohibition 1800–1928. Oxford: Oxford University Press.

Myran, D.T., Cantor, N., Finkelstein, Y., Pugliese, M., Guttmann, A., Jesseman, R. and Tanuseputro, P. (2022) 'Unintentional pediatric cannabis exposures after legalization of recreational cannabis in Canada', JAMA Network Open, 5(1), e2142521. doi:10.1001/jamanetworkopen.2021.42521.

Myran, D.T. et al. (2025) 'Changes in incident schizophrenia diagnoses associated with cannabis use disorder after cannabis legalization', JAMA Network Open, February 2025. Available at: https://pubmed.ncbi.nlm.nih.gov/39903464/.

National Academies of Sciences, Engineering, and Medicine (2017) The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington, DC: The National Academies Press. Available at: https://www.ncbi.nlm.nih.gov/books/NBK425762/.

Nutt, D.J., King, L.A. and Phillips, L.D. (2010) 'Drug harms in the UK: a multicriteria decision analysis', The Lancet, 376(9752), pp. 1558–1565. doi:10.1016/S0140-6736(10)61462-6.

Petrilli, K., Ofori, S., Hines, L., Taylor, G., Adams, S. and Freeman, T.P. (2022) 'Association of cannabis potency with mental ill health and addiction: a systematic review', The Lancet Psychiatry, 9(9), pp. 736–750. doi:10.1016/S2215-0366(22)00161-4.

Pharmaceutical Journal (2024) 'Prescriptions for cannabis-based medicines double in a year, CQC report says'. Available at: https://pharmaceutical-journal.com/article/news/prescriptions-for-cannabis-based-medicines-double-in-a-year-cqc-report-says.

Queirolo, R., Repetto, L., Alonso, J., Álvarez, E., Sotto, B., Pardal, M. and Kilmer, B. (2024) 'Intended and unintended effects of cannabis regulation in Uruguay'. Available at: https://repositorio.ausjal.org/handle/20.500.12032/179430.

Rolles, S. and Murkin, G. (2016) How to Regulate Cannabis: A Practical Guide. 2nd edn. Bristol: Transform Drug Policy Foundation.

Room, R., Fischer, B., Hall, W., Lenton, S. and Reuter, P. (2010) Cannabis Policy: Moving Beyond Stalemate. Oxford: Oxford University Press.

Tweet, M.S., Nemanich, A. and Wahl, M. (2023) 'Pediatric edible cannabis exposures and acute toxicity: 2017–2021', Pediatrics, 151(2), e2022057761. doi:10.1542/peds.2022-057761.

United Nations (1961) Single Convention on Narcotic Drugs, 1961. New York, 30 March 1961. United Nations Treaty Series, vol. 520.

UNODC (2020) CND votes on recommendations for cannabis and cannabis-related substances. Vienna, 3 December 2020. Available at: https://www.unodc.org/unodc/en/frontpage/2020/December/cnd-votes-on-recommendations-for-cannabis-and-cannabis-related-substances.html.

UNODC (2025) World Drug Report 2025. Vienna: United Nations Office on Drugs and Crime.

UNODC (2026) World Drug Report 2026: Drug use. Vienna: United Nations Office on Drugs and Crime. Available at: https://data.unodc.org/wdr2026.