Eleven states in the US have legalised recreational cannabis use though cannabis remains prohibited under federal law – Colorado and Washington in 2012, Alaska and Washington DC in 2015, California, Massachusetts and Oregon in 2016, Maine and Nevada in 2017, Michigan and Vermont in 2018, and Illinois in 2020.[1] For many states this law change followed the establishment of a medicinal cannabis market and previous decriminalisation of cannabis use.
In most states where recreational use of cannabis has been legalised, cannabis can be purchased in unlimited strengths and forms from retail stores, with the exception of Washington DC and Vermont. All states have a highly commercialised industry with privately run retail stores and advertising is allowed, except Vermont and DC where retail stores are illegal and cannabis use is limited to home growing and gifting. The state governments impose taxes on cannabis and sometimes local governments add taxes. The differences between the state and federal laws create a number of issues and while prohibited at a federal level there are limits to the expansion of the state-specific industries.
The minimum age of purchase of 21 aligns to the age limit for alcohol. Consumption is allowed on private property and some jurisdictions allow onsite consumption. Limits on the amount that can be purchased in one transaction and the personal public possession limit range from 28 grams to 71 grams across states, as does the home grow limits (where it is allowed) ranging up to 15 plants with only two or three mature plants, but prohibited in a few states. Except for Washington, none have a cap on the total amount of cannabis (or THC) that can be produced and sold but all have limits on THC in edibles.[2] Driving under the influence is a criminal offence – varying thresholds applied in different states from zero tolerance to <5 ng THC.[3]
The body of evidence on the impacts of legalisation of cannabis across different states is growing but conflicting in many cases due to regulatory, contextual and study differences. For example, the effects on traffic fatalities, incidence and prevalence of mental health issues and other substance use, including alcohol and opioids, are unclear.[4] A study that evaluated the effect of changes in cannabis policy on per capita cigarette and alcohol consumption found no strong positive or negative effect on either alcohol or cigarette sales.[5] In Washington, there were no significant changes in the amount of people using cannabis and alcohol together or overall alcohol consumption, but there was a significant increase in any cannabis use and decreases in alcohol-related harms at home and alcohol-related financial harms.[6]
Evidence is more consistent that emergency room visits have increased for cannabis-related medical conditions, including short-term psychological effects such as anxiety, suicidal ideations/tendencies and psychotic symptoms, vomiting, and accidental poisoning of children from ingestion.[7] An increase in cannabis exposures reported to the US National Poison Data System of 5.06-5.80 more exposures per 1,000,000 population per quarter (67-77% increase relative to the pre-legalisation average) was observed following recreational cannabis commercialisation in the US.[8] There is also evidence that the price of legal cannabis has decreased in places where recreational cannabis use has been legalised – for example, wholesale prices declined more than 60% from January 2015 to October 2018, from $2007 to $758 for a pound of cannabis.[9]
The impacts on rates of use are unclear and differ by age group. Including data following legalisation of medicinal cannabis there has been an increased frequency of use and of cannabis use disorder among adult users but no clear impact on rates of use or of cannabis use disorders in youth.[10] For example, one study in Washington State showed an increase in use and declining perception of the harmfulness of cannabis for 8th and 10th graders, but no change for 12th graders.[11] Another study showed a decrease in youth use.[12] In Colorado, no significant change in perception of harm or prevalence of use in youth has been observed following legalisation.[13] Another study found that the increase in rates of cannabis use disorder in 12-17 year olds is 25% higher in states where cannabis has been legalised, but these findings may be caused by other factors, and no differences were reported for those aged 18-25.[14] Evidence suggests potential increases in college student use.[15] An increased use among pregnant and parenting women after cannabis legalisation has been reported in Washington, but this was not associated with changes in the prevalence of low birth weight or small for gestational age births during the same interval.[16]
Cannabis-related criminal activity and other reported crimes (rape, property crimes and thefts) have decreased, and police clearance rates either remained unchanged or improved following recreational cannabis legalisation.[17] A decrease in cannabis arrests in Colorado has occurred, with a decline in lower level offences, but not more serious crimes, and an increase in organised crime.[18] In Washington, there has been no change in the racial disparity of cannabis-related arrests after legalisation, with disparities in arrest rates for African Americans increasing for those of legal purchase age and remaining unchanged for youth.[19] In Oregon, the disparities in arrest rates between African Americans and Caucasians decreased following legalisation, but were unchanged for Native Americans.[20] There was also an increase in youth cannabis offences following legalisation that was not explained by an increase in use.
Legalisation has stimulated innovation in products, with a proliferation of products on offer, including highly potent products and different ways to consume these.[21] For example, a new store in Oakland, California reports selling over 500 products and data from sales in Colorado and Washington suggest that cannabis flower accounts for a decreasing share of cannabis products purchased. While edibles and THC-infused beverages account for some of the non-flower market, the fastest growing segments of the markets are the extracts for inhalation which include vaporiser pens, oils and waxes.[22] Impacts of these on public health may take some years to become apparent.
The illegal market for cannabis remains even in states where legal purchase is possible, but it is decreasing. This likely reflects the time it takes for the commercial industry to take hold. An increasing share of people are sourcing their cannabis from the legal market in states that have been established for a longer time, such as in Colorado.[23] The illegal status of cannabis in neighbouring states is thought to be a contributing factor to the illegal market remaining, as well as compliance costs to get into the legal cannabis business. For example, despite legalising cannabis in 2016, California still has a thriving illegal market, with as much as 80% of all cannabis sales being linked to illegal sources. Recent economic estimates suggest that California’s illicit cannabis market is worth approximately $3.7 billion—more than four times the size of the legal market in the state.[24]
How does this compare to Aotearoa New Zealand’s proposed law?
Compared to the majority of US states where recreational cannabis has been legalised, Aotearoa New Zealand’s proposed law has stronger regulations for the production and sale of cannabis. Being a national law, the law in Aotearoa New Zealand law will result in greater uniformity in regulation than what is seen among states in the US. Aotearoa New Zealand’s home grow and purchase limits are lower than those in the US states. There will also be limits to THC potency, which are only applied to edibles in the US states with legal cannabis. Unlike most of the US states, advertising will not be allowed. The US age limit is higher than Aotearoa New Zealand’s, matching their higher alcohol age limit.
References
[1] Lancione et al., “Non-Medical Cannabis in North America: An Overview of Regulatory Approaches,” Public Health 178 (2020)
[2] Washington initially limited production but this cap was eventually lifted. Kilmer, “How Will Cannabis Legalization Affect Health, Safety, and Social Equity Outcomes? It Largely Depends on the 14 Ps,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[3] Kilmer, “How Will Cannabis Legalization Affect Health, Safety, and Social Equity Outcomes? It Largely Depends on the 14 Ps,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[4] Leung et al., “What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects,” Current Addiction Reports 6, no. 4 (2019); Smart et al., “Early Evidence of the Impact of Cannabis Legalization on Cannabis Use, Cannabis Use Disorder, and the Use of Other Substances: Findings from State Policy Evaluations,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[5] Veligati et al., “Changes in Alcohol and Cigarette Consumption in Response to Medical and Recreational Cannabis Legalization: Evidence from U.S. State Tax Receipt Data,” International Journal of Drug Policy 75 (2020)
[6] Subbaraman et al., “Subgroup Trends in Alcohol and Cannabis Co-Use and Related Harms During the Rollout of Recreational Cannabis Legalization in Washington State,” International Journal of Drug Policy 75 (2020)
[7] Leung et al., “What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects,” Current Addiction Reports 6, no. 4 (2019)
[8] Shi et al., “The Association between Recreational Cannabis Commercialization and Cannabis Exposures Reported to the Us National Poison Data System,” Addiction (2020)
[9] Kilmer, “How Will Cannabis Legalization Affect Health, Safety, and Social Equity Outcomes? It Largely Depends on the 14 Ps,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[10] Leung et al., “What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects,” Current Addiction Reports 6, no. 4 (2019); Smart et al., “Early Evidence of the Impact of Cannabis Legalization on Cannabis Use, Cannabis Use Disorder, and the Use of Other Substances: Findings from State Policy Evaluations,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[11] Cerdá et al., “Association of State Recreational Marijuana Laws with Adolescent Marijuana Use,” JAMA Pediatrics 171, no. 2 (2017): 142-49
[12] Dilley et al., “Prevalence of Cannabis Use in Youths after Legalization in Washington State,” JAMA Pediatrics 173, no. 2 (2019): 192-93
[13] Cerdá et al., “Association of State Recreational Marijuana Laws with Adolescent Marijuana Use,” JAMA Pediatrics 171, no. 2 (2017): 142-49
[14] Cerdá et al., “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, no. 2 (2020): 165-71
[15] Smart et al., “Early Evidence of the Impact of Cannabis Legalization on Cannabis Use, Cannabis Use Disorder, and the Use of Other Substances: Findings from State Policy Evaluations,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[16] Bahji et al., “International Perspectives on the Implications of Cannabis Legalization: A Systematic Review & Thematic Analysis,” International Journal of Environmental Research and Public Health 16, no. 17 (2019)
[17] Bahji et al., “International Perspectives on the Implications of Cannabis Legalization: A Systematic Review & Thematic Analysis,” International Journal of Environmental Research and Public Health 16, no. 17 (2019)
[18] Reed, Impacts of Marijuana Legalization in Colorado: A Report Pursuant to Senate Bill 13-283. Colorado Department of Public Safety, Division of Criminal Justice, 2018.
[19] Firth et al., “Did Marijuana Legalization in Washington State Reduce Racial Disparities in Adult Marijuana Arrests?,” Substance Use & Misuse 54, no. 9 (2019)
[20] Firth et al., “Implications of Cannabis Legalization on Juvenile Justice Outcomes and Racial Disparities,” American Journal of Preventive Medicine (2020)
[21] Leung et al., “What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects,” Current Addiction Reports 6, no. 4 (2019)
[22] Kilmer, “How Will Cannabis Legalization Affect Health, Safety, and Social Equity Outcomes? It Largely Depends on the 14 Ps,” The American Journal of Drug and Alcohol Abuse 45, no. 6 (2019)
[23] Orens et al., “Market Size and Demand for Marijuana in Colorado: 2017 Market Update,” Boulder, CO: Marijuana Policy Group (2018)
[24] Bahji et al., “International Perspectives on the Implications of Cannabis Legalization: A Systematic Review & Thematic Analysis,” International Journal of Environmental Research and Public Health 16, no. 17 (2019)