Legalising cannabis in Aotearoa New Zealand: What does the evidence say?

To help people decide how they will vote in the upcoming referendum, we have summarised what we know about the possible impacts of legalising cannabis.

This information focuses on the impact of legalising recreational cannabis use, not on the medicinal uses of cannabis, which has its own law.

Many people have preconceptions and established beliefs about whether cannabis is good or bad, harmless or risky. The topic is complex and multifaceted. There may be implications of legalisation you haven’t yet considered. Here we provide balanced information from trusted sources that covers a broad range of areas impacted by cannabis, including health and social impacts.

This work was informed by a diverse panel of researchers and clinicians. Each individual contributed information and their expertise, drawing on research from here and overseas to collectively review the available information. As this topic is complex and there are gaps in research and scientific data, we did not reach uncontested conclusions or agree on every single point. But we tried to reach a consensus on as many aspects as possible.

vote iconWhat might happen if you vote yes or no?

We have summarised the available evidence related to cannabis legalisation into an ‘at a glance’ summary.

Watch: Science and the cannabis referendum

This independent documentary by Shirley Horrocks includes commentary from some members of our panel.

Prohibition vs legalisation

Our current law uses a ‘prohibition’ approach to cannabis. The threat of arrest or conviction is intended to put people off using cannabis, therefore avoiding any associated social or health problems. But cannabis being illegal isn’t stopping people using it and, as a result, society experiences substantial social and health harms related to cannabis. Because of the harms arising with prohibition, some people are concerned about the impacts of current drug laws – particularly on certain groups – and advocate for drug law reform. Some advocates for drug law reform also note that prohibiting cannabis restricts personal freedoms in a way that is inconsistent with our ability to choose to drink alcohol or smoke tobacco. On the other hand, people argue that prohibition is in line with Aotearoa New Zealand’s international obligations under United Nations drug conventions and that prohibition provides a symbolic and legal deterrent to cannabis use.[1]

Though cannabis use is currently prohibited by The Misuse of Drugs Act in Aotearoa New Zealand, over the past decade the regulation has morphed into a ‘soft decriminalisation’ approach. The extent to which the law is enforced has eased. The most recent change in August 2019 affirmed police discretion to take a health-centred approach rather than prosecuting those in possession of drugs. It is too early to have solid evidence for the difference this approach has made to cannabis use, enforcement and harm. However, early signs, supported by a wealth of related evidence here and overseas, suggests that such discretion may not be applied equally. Discriminatory policing and justice outcomes result from the uneven application of cannabis laws, especially for Māori.[2]

An alternative approach being implemented in some jurisdictions is to legalise the production, supply and use of cannabis. In theory, this approach has the potential to undercut the illegal market for cannabis, help reduce cannabis-related harm through regulated product safety, better facilitate intervention and treatment services, and separate access to cannabis from the illegal market for more harmful drugs. Whether this plays out in reality is yet to be determined, as legalisation reforms in other places have not been in place for long enough for a full evaluation of long-term impacts. There is an inevitable lag before evidence of changes in health and social measures emerge. It also takes some time for the effects of commercialisation of cannabis to eventuate where a profit-oriented approach is taken.

The impacts of cannabis law reform also depend on the specific regulations and how these are implemented and enforced in each jurisdiction. For example, Uruguay has a more strict government-controlled supply of cannabis as opposed to the more liberal, commercialised markets for cannabis, similar to alcohol, seen in some states in the US. Canada’s system of legal supply is a hybrid of these two systems, with a commercial cannabis industry and limited retail and use provisions. Ultimately, the impacts we see in Aotearoa New Zealand will not be determined by whether cannabis is legalised, but by the specific details in the regulation. The specific regulatory framework in the draft bill is therefore a critical consideration in deciding which way to vote in the referendum.

The impacts we see in Aotearoa New Zealand will not be determined by whether cannabis is legalised, but by the specific regulatory details in a legal framework

The Coalition Government has proposed a regulatory framework for legalising cannabis – see ‘What are we voting on?’

 

[1] European Monitoring Centre for Drugs and Drug Addiction, “Technical Report: Monitoring and Evaluating Changes in Cannabis Policies: Insights from the Americas “, 2020

[2] JustSpeak, “A Justice System for Everyone”, 2020; Alice Webb-Liddall, “Balancing Justice’s Racist Scales”, Matters of Substance, November 2019

Frequently asked questions

What are we voting on?

The referendum is about legalising recreational use of cannabis. The government has outlined the details of what the legalisation framework would be in Aotearoa New Zealand to control the use and supply of cannabis.

A person aged 20 or over would be able to:

  • buy up to 14 grams of dried cannabis (or its equivalent) per day, but only from businesses with a licence to sell cannabis
  • enter licensed premises where cannabis is sold or consumed, but not smoke or vape inside (and alcohol and tobacco cannot also be sold there)
  • consume cannabis on private property or at a licensed premise, but not in public
  • grow up to two plants, with a maximum of four plants per household, but out of sight or not accessible by the public
  • share up to 14 grams of dried cannabis (or its equivalent) with another person aged 20 or over, but it would be illegal to supply cannabis to anyone under 20.

Any cannabis for sale through a licensed vendor would:

  • have been through an approval process that controls the potency (strength), quality and contents of the cannabis
  • be an approved product type (e.g. dried cannabis) and not a prohibited type (e.g. those that appeal to children such as gummy bear edibles)
  • come in plain packaging with health warnings and details of how the product compares to the daily purchase limit
  • be taxed, with a higher rate for more potent cannabis, and levied to fund services to reduce cannabis harm
  • only be available in locations and during opening hours that are established in consultation with the local community
  • not be promoted or advertised outside the store.

Further details about the regulation of the supply chain, licencing, taxes and more are available at referendums.govt.nz. The bill includes proposed ways to decrease rather than increase social disparities through community involvement, input and employment in the cannabis industry, particularly for Māori and economically deprived communities.

Note that the final draft Bill is available to inform the referendum. If the majority of people vote ‘yes’, the Bill would still need to go through parliament and the public would have an opportunity to provide input on the details. Therefore some details of the bill could change before the regulation was implemented.

The referendum is about legalising recreational use of cannabis

  • The vote is for legalisation not decriminalisation – these are different. Decriminalising cannabis means that it is no longer a criminal offence to use cannabis, but a civil penalty may still be applied, such as a fine. In places where cannabis has been decriminalised it remains illegal to grow or sell cannabis and an illegal market is relied on for supplying the drug. Examples of countries that have decriminalised cannabis include the Netherlands, Portugal and some states in Australia and the United States. Aotearoa New Zealand took a step towards decriminalisation with the alteration to the Misuse of Drugs Act in August 2019 which affirms police discretion to take a health-oriented approach rather than prosecuting people who use cannabis. In contrast, legalisation means that the production, supply and use of cannabis are legal in accordance with the specific regulations.
  • There are different laws for recreational and medicinal use of cannabis. Medicinal cannabis is where cannabis is used as a treatment or medication for people with certain health conditions as prescribed by a doctor. Recreational use of cannabis refers to most other use (some of which involves self-medication). Aotearoa New Zealand’s laws relating to medicinal cannabis changed in 2019. The current referendum is only about recreational use. If recreational cannabis is legalised, cannabis will be legally available without medical advice.
  • Synthetic cannabis is illegal and is not included in the proposed law change. So-called synthetic cannabis contains chemical compounds called synthetic cannabinoids sprayed onto a smokeable plant material e.g. products sold as K2 or Spice. These chemicals are made in a lab to attempt to mimic the effects of cannabis but can be more potent and cause significant physical and mental harm, including seizures, irregular heartbeat, hallucinations and in rare cases, death. Compared with natural cannabis products, most synthetic cannabis products are stronger and more dangerous – becoming more so with each new generation of cannabinoids developed. Unlike natural cannabis, there is a risk of overdose with synthetic cannabinoids. In recent years, despite being illegal, rates of use for synthetic cannabis have increased.

If recreational cannabis is legalised, cannabis will be legally available without medical advice

See ‘What happens if you get caught with cannabis now? How would it change?’

What happens if you get caught with cannabis now? How would it change?

It is currently illegal to possess, deal or grow cannabis in Aotearoa New Zealand. Though cannabis use is controlled through the criminal justice system, the focus on enforcing cannabis laws has substantially eased over the past decade in Aotearoa New Zealand, morphing into more of a ‘soft decriminalisation’ approach.

If cannabis is legalised, it would be legal for an individual aged 20 or older to possess 14 grams of cannabis and grow up to two plants at home (to a maximum of four per household). However, there would still be cannabis-related offences for breaking the new law. For example, it would still be an offence for people younger than 20 to use cannabis, for anyone to deal cannabis without a license, to supply people under the age of 20 with cannabis, and to drive while impaired.

There would still be cannabis-related offences for breaking the new law

OffenceUnder the proposed legal frameworkCurrent law
PossessionThe proposed regulation for cannabis would limit individual purchases to 14 grams of dried cannabis (or its equivalent) per day – the same as the limit for the amount a person can have in public. The panel estimates this is equivalent to around 30 joints. The purchase limit accounts for the likelihood that people would purchase enough cannabis to use over a longer period of time in one transaction, in the same way that we buy a cask of wine or a case of beer.

The proposed limits are lower than the possession limits in US states (most commonly 28 grams, but up to 71 grams) and Canada (30 grams), but higher than the purchase limits for Uruguay (10 grams per week or 40 grams per month).

It is unclear how purchase limits will be managed.
The maximum penalty for possession of cannabis is three months in prisonor a fine of up to $500, or both.

Police have the discretion to take a health-oriented approach rather than prosecuting those in possession of cannabis, unless they think it is in the public good to do so. If cannabis possession is the only offence it is likely a person will be directed to treatment or counselling rather than the criminal justice system.

The August 2019 change is likely to result in a (possibly large) decrease in the number of convictions for cannabis use. However, inherent biases in police discretion already lead to disproportionate arrests and convictions of Māori for cannabis possession. This suggests that this law change may not address social inequities as much as legalisation of cannabis could.
Youth possessionPeople younger than 20 would be prohibited from growing, possessing and consuming cannabis.

Those caught with cannabis would receive a health-based response such as an education session, social or health service, or they would pay a small fee or fine if found in possession of cannabis. This would not lead to a conviction.
Most people under 17 who are caught with cannabis will receive a warning, diversion, or require a family group conference if it is their first offence and they only had small amounts for personal use. More serious cases are addressed in the Youth Court.
DealingSelling cannabis will only be legal for licensed stores. All other sales via the illicit market will remain illegal.

Supplying cannabis to a person aged 19 years or younger would carry a fine or prison sentence, with a maximum penalty of 4 years in prison or fine of $150,000.
The maximum penalty for dealing cannabis is eight years in prison.
GrowingThe proposed regulation allows for individuals to grow up to two plants at home, with a maximum of four plants for two or more adults at the same house. If a person grows more than that (up to 10 plants) they will be fined but not convicted.

There is no limit for total annual production from home growing. Of other places that have legalised cannabis, only Uruguay has set a production limit from home growing to 480 grams per year. The panel estimates that the amount of cannabis that could be grown from two plants per person is less than what could be purchased based on the daily purchase limit of 14 grams.
The maximum penalty for growing cannabis is seven years in prison, but the charge depends on the amount being grown and if the person is dealing it.
Driving while impairedThe bill does not cover driving while impaired. A new compulsory random roadside oral fluid testing scheme is being introduced regardless of whether cannabis becomes legal or remains illegal. The threshold for a criminal offence will be aligned with that for alcohol. An independent expert panel is advising the government on the test. It is an offence to drive while impaired by cannabis. Potential penalties include up to three months in prison, or a fine up to $4,500 and disqualified licence for at least six months. At the higher end of the spectrum, penalties may include 10 years in prison, or a fine up to $20,000 and disqualified licence for at least one year.

Roadside testing for drugs, including cannabis, is being introduced regardless of the referendum outcome. A new compulsory random roadside oral fluid testing scheme will include testing for cannabis.. The threshold for a criminal offence will be aligned with that for alcohol. An independent expert panel is advising the government on the test.
Positive drug test at workLegalisation will not affect the right of employers to test employees for cannabis use. For example, employers can still have policies (or contractual provisions) that require negative drug tests before they will employ someone to use heavy machinery.Employers have the right to test for cannabis, as long as they have a policy in place (or contractual provision) that provides for drug testing.

For further details about the proposed regulatory framework for cannabis in Aotearoa New Zealand, see ‘What are we voting on?’

What are the social and community impacts of cannabis prohibition?

Laws that make people who use cannabis criminals cause harm.[1] Prosecuting a person for cannabis use subjects them to a criminal process that may stigmatise them for the rest of their life and in some cases expose them to prison.[2] These social harms do not impact everyone in the same way because not everyone is treated the same when it comes to enforcing the law. Some people and communities come under far greater levels of scrutiny and surveillance by state agents, particularly the police, than others.

In Aotearoa New Zealand, systemic racism in the justice system means that Māori are disproportionately more likely to be arrested, sentenced and convicted for drug offences, including cannabis-related crimes.[3] As a result, the social harms from our current cannabis laws disproportionately fall on Māori communities and young people, exacerbating inequality and social problems. For people and communities disproportionately affected and criminalised under punitive drug regimes, criminalisation of cannabis use may cause more harm than cannabis use itself.[4]

Māori are disproportionately more likely to be arrested, sentenced and convicted for drug offences, including cannabis-related crimes

  • Illegal cannabis use, production and supply activities are embedded in deprived communities. This gives rise to organised and opportunistic crime, compromises social wellbeing and safety, and exerts disproportionate and inter-generational social harms associated with cannabis in these communities. Some people in these communities rely on the illegal market as a source of income and further harm may be caused if these people cannot benefit from the legal market. Māori already have greater barriers for accessing health and other services and cannabis prohibition means that for marginalised groups a justice approach rather than a health approach is more likely in the current legal framework.[5]
  • Having a drug conviction leads to the loss of many opportunities over a person’s lifetime. Sometimes referred to as ‘harm from drug conviction’, this includes reduced job prospects, difficulty finding housing, missing out on getting an education, or being unable to travel overseas.
  • A low-level cannabis conviction can have a snowball effect in the justice system. The harms cascade within the broader justice system. For example, having a prior conviction influences whether a person is bailed or remanded in custody – therefore exposing a person to prison time. Housing issues that result from a drug conviction, even a low-level cannabis conviction, may also make a person less likely to be bailed because they do not have an address that is approved by the police and courts.
  • Cannabis convictions also affect family and whānau, in many cases further embedding poverty. Formal interactions with the criminal justice system often means ongoing association with people and systems that are likely to lead to other criminal behaviour.

See ‘How would legalising cannabis impact Māori specifically?’

 

[1] Transform Drug Policy Foundation, How to Regulate Cannabis: A Practical Guide (Transform Drug Policy Foundation, 2016)

[2] Eastwood et al., “A Quiet Revolution: Drug Decriminalisation across the Globe”, 2016

[3] Department of Corrections, “Over-Representation of Māori in the Criminal Justice System: An Exploratory Report”, 2007; Te Uepū Hāpai i te Ora – the Safe and Effective Justice Advisory Group, “He Waka Roimata: Transforming Our Criminal Justice System”, 2019; JustSpeak, “A Justice System for Everyone”, 2020; Te Uepū Hāpai i te Ora – the Safe and Effective Justice Advisory Group, “Turuki! Turuki! Moving Together”, 2019

[4] Te Uepū Hāpai i te Ora – the Safe and Effective Justice Advisory Group, “He Waka Roimata: Transforming Our Criminal Justice System”, 2019; JustSpeak, “A Justice System for Everyone”, 2020; Te Uepū Hāpai i te Ora – the Safe and Effective Justice Advisory Group, “Turuki! Turuki! Moving Together”, 2019

[5] Theodore et al., “Cannabis, the Cannabis Referendum and Māori Youth: A Review from a Lifecourse Perspective,” Kōtuitui: New Zealand Journal of Social Sciences Online (2020): 1-17; Health Quality and Safety Commission New Zealand, “A Window on the Quality of Aotearoa New Zealand’s Health Care 2019”, 2019

How would legalisation of cannabis impact Māori specifically?

Māori have borne the brunt of biased enforcement and the negative health effects of cannabis being illegal.[1] Legalising cannabis could have important positive implications for social equity outcomes, particularly for Māori. Legalisation has the potential to formally address some of the bias in the justice system by placing Māori on a substantively equal footing with other citizens regarding cannabis use.

Legalising cannabis could have important positive implications for social equity outcomes, particularly for Māori

See ‘What happens if you get caught with cannabis now? How would it change?’

 

[1] Theodore et al., “Cannabis, the Cannabis Referendum and Māori Youth: A Review from a Lifecourse Perspective,” Kōtuitui: New Zealand Journal of Social Sciences Online (2020): 1-17

[2] Fergusson et al., “Arrests and Convictions for Cannabis Related Offences in a New Zealand Birth Cohort,” Drug and Alcohol Dependence 70, no. 1 (2003)

[3] Fergusson et al., “Arrests and Convictions for Cannabis Related Offences in a New Zealand Birth Cohort,” Drug and Alcohol Dependence 70, no. 1 (2003)

[4] Theodore et al., “Cannabis, the Cannabis Referendum and Māori Youth: A Review from a Lifecourse Perspective,” Drug and Alcohol Dependence 70, no. 1 (2003)

[5] JustSpeak, “A Justice System for Everyone”, 2020

[6] Derek Cheng and Anna Leask, “Outgoing Police Commissioner Mike Bush Opens up About Police Bias, Tragedy and Trauma Counselling”, NZ Herald, 2 April 2020; Mihingarangi Forbes. “Police Commissioner Andrew Coster Agrees Unconscious Bias Still Exists within Police”, Newshub, 14 June 2020

[7] Walker, “Issues of Tobacco, Alcohol and Other Substance Abuse for Māori”, 2019; Theodore et al., “Cannabis, the Cannabis Referendum and Māori Youth: A Review from a Lifecourse Perspective,” Drug and Alcohol Dependence 70, no. 1 (2003)

[8] Alice Webb-Liddall, “Balancing Justice’s Racist Scales,” Matters of Substance, November 2019

[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] 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)

How does cannabis compare to alcohol and tobacco?

It is generally accepted that cannabis does less harm than alcohol and tobacco in society.[1] Part of the reason is likely to be because more people use alcohol and tobacco than cannabis, but it also relates to the different impacts on people who use them and the frequency of use among those who try the substances.

It is generally accepted that cannabis does less harm than alcohol and tobacco in society

Studies have shown that cannabis causes lower levels of harm than alcohol and tobacco across different measures of harm, including physical harm, dependence on the substance, and social harm.[2] One particular study from the UK based on expert ranking of the harm caused by cannabis, alcohol and tobacco concluded that cannabis only ranked higher than tobacco for intoxication and social harm – for all other measures it was lower than both alcohol and tobacco (the data from this study is pulled out in the table below).[3] This study is from 2007 and as the potency of cannabis products increases over time, harm from cannabis is also likely to increase.

A separate analysis put forward a counter view and pointed out that, based on the US National Survey on Drug Use and Health, the self-reported rate of dependence and abuse are higher for cannabis than alcohol per user.[4] The research suggests that by including people who have merely tried cannabis in the assessments of risk from the substance, it dilutes the harm to those who use it on an ongoing basis, and concludes that it would be far more accurate to say “[Cannabis] is safer than alcohol, but it is also more likely to harm its users.”[5]

Comparison of the mean harm scores for cannabis, alcohol and tobacco based on a four-point scale of risk from no risk (0) to extreme risk (3), scored by independent groups of experts from a 2007 study

 CannabisAlcoholTobacco
Physical harm1.01.41.2
- Acute0.91.90.9
- Chronic2.12.42.9
Dependence1.51.92.2
- Pleasure1.92.32.3
- Psychological1.71.92.6
- Physical0.81.61.8
Social harm1.52.21.4
- Intoxication1.72.20.8
- Social harm1.32.41.1
- Healthcare costs1.52.12.4

We can learn from the experiences of trying to reduce harm caused by alcohol and tobacco and apply these to cannabis. There is clear guidance on how society can reduce its alcohol-related problems.[6] These include restricting the marketing of products, increasing the price, reducing accessibility, setting a higher minimum legal purchase age, strengthening drink driving countermeasures and increasing treatment opportunities for heavy users. Some equivalent measures for cannabis have been included in the proposed regulatory framework, including a ban on marketing and having a higher legal purchase age than alcohol. Setting the price of legal cannabis needs to strike a balance between having a competitive price to draw people away from the illegal market while also maintaining a price that deters frequent use.

Lessons from tobacco show that health warnings increase perceptions of risk, decrease use, and increase the use of services to help quit smoking.[7] Under the proposed legal framework, health warnings will be mandatory on cannabis products. Restrictions on advertising and marketing tobacco products have also been influential in reducing use and social norms and this is proposed for the regulatory framework for legal cannabis.

Some harm reduction measures may also need to be culturally specific. Drawing on evidence from alcohol use, the proportion of Pacific people who drink alcohol is lower than the general population but the drinking patterns for those who do drink appear to be more harmful (e.g. consume more, report violence and injury).[8] In the development of alcohol harm reduction strategies for young Pacific people, traditional beliefs, church, family and peer groups are particularly important.[9] Harm reduction strategies for cannabis may require similar approaches across different cultures in Aotearoa New Zealand’s highly multicultural context.

 

[1] Hall, “Alcohol and Cannabis: Comparing Their Adverse Health Effects and Regulatory Regimes,” International Journal of Drug Policy 42 (2017); Nutt et al., “Development of a Rational Scale to Assess the Harm of Drugs of Potential Misuse,” The Lancet 369, no. 9566 (2007)

[2] Nutt et al., “Drug Harms in the Uk: A Multicriteria Decision Analysis,” The Lancet 376, no. 9752 (2010); Lachenmeier et al., “Comparative Risk Assessment of Alcohol, Tobacco, Cannabis and Other Illicit Drugs Using the Margin of Exposure Approach,” Scientific Reports 5, no. 1 (2015); Nutt et al., “Development of a Rational Scale to Assess the Harm of Drugs of Potential Misuse,”

[3] Nutt et al., “Development of a Rational Scale to Assess the Harm of Drugs of Potential Misuse,” The Lancet 369, no. 9566 (2007)

[4] Caulkins, “The Real Dangers of Marijuana,” National Affairs,(Winter 2016) 2134 (2016)

[5] Caulkins, “The Real Dangers of Marijuana,” National Affairs,(Winter 2016) 2134 (2016)

[6] Sellman, “Ten Things the Alcohol Industry Won’t Tell You About Alcohol,” Drug and Alcohol Review 29, no. 3 (2010); World Health Organization, “Global Strategy to Reduce the Harmful Use of Alcohol”, 2010

[7] Hammond, “Health Warning Messages on Tobacco Products: A Review,” Tobacco Control 20, no. 5 (2011)

[8] Huakau et al., “New Zealand Pacific Peoples’ Drinking Style: Too Much or Nothing at All?,” New Zealand Medical Journal (online) 118, no. 1216 (2005)

[9] Huakau et al., “New Zealand Pacific Peoples’ Drinking Style: Too Much or Nothing at All?,” New Zealand Medical Journal (online) 118, no. 1216 (2005)

Why is the age limit 20?

It is safer to wait until age 18 before using cannabis, and even better to wait until age 25, but young people are the biggest users of cannabis. The age limit for legalised cannabis needs to strike a balance between reducing access for young people and making sure access is safer for young people who use cannabis through regulation and education. The proposed legal age limit of 20 is a relatively arbitrary cut-off to strike that balance.

Evidence to support the decision for a minimum legal age is limited. A recent Canadian study found that most later-life outcomes are better for individuals starting cannabis at age 19 than those starting it at age 18 but not worse than those starting cannabis between age 20 and 25.[1]

Young people are the biggest users of cannabis

The age for using and purchasing cannabis is not consistent with the limits for alcohol and tobacco, which also differ (see table below). It does align to the age limit for gambling in a casino. Other states and countries that have legalised recreational cannabis have aligned the cannabis age to the alcohol age limit. However, we know that the current age limit of 18 for alcohol and tobacco contributes to the harms associated with those substances. In particular, alcohol-related harms increased when the minimum purchase age of alcohol was lowered from 20 to 18 in 1989.[2]

ProductLegal use ageLegal purchase age
AlcoholNone18
Tobacco1818
Cannabis (proposed)2020

 

[1] Nguyen et al., “Too Young for Cannabis? Choice of Minimum Legal Age for Legalized Non-Medical Cannabis in Canada,” BMC Public Health 20, no. 1 (2020)

[2] Huckle et al., “Trends in Alcohol‐Related Harms and Offences in a Liberalized Alcohol Environment,” Addiction 101, no. 2 (2006); Law Commission, “Alcohol in Our Lives: An Issues Paper on the Reform of New Zealand’s Liquor Laws,” (2009)

Has cannabis always been illegal in Aotearoa New Zealand?

No – humans have a long history of cannabis use and criminalisation is relatively recent.[1] When Europeans arrived in Aotearoa New Zealand they brought drugs with them in the form of medications. This included the children’s cough medicine chlorodyne that contained both cannabis and opium and Dr TK Douglas’ ‘Māori cigarettes’ that claimed to cure asthma, hay fever and whooping cough. Cannabis was cheap, freely available, and even listed in the popular book New Zealand Family Herb Doctor (1889).[2]

Despite its widespread acceptance, opposition to cannabis emerged in the 19th century. By 1927, the Dangerous Drugs Act brought Aotearoa New Zealand in line with international restrictions by listing cannabis as a dangerous drug. In 1955, Aotearoa New Zealand agreed with the World Health Organization to end cannabis imports. As a result, there was little use or knowledge of cannabis here until the 1960s. But overseas influences meant things soon changed and the drug-taking message quickly spread. Before 1964, annual drug arrests numbered fewer than 50, but by 1990 there were more than 18,000 prosecutions and over 150,000 cannabis plants seized.[3]

 

[1] Royal Society Te Apārangi, “Cannabis: How It Affects Our Health,” (2019)

[2] Jock Phillips, “Drugs”  http://www.TeAra.govt.nz/en/drugs

[3] Jock Phillips, “Drugs” http://www.TeAra.govt.nz/en/drugs

Is legalising cannabis the first step to legalising other drugs?

Worldwide, there is a shift towards health-centred approaches, with an increasing number of jurisdictions implementing legalisation. Many others have decriminalised possession, meaning that people caught with small amounts do not get criminal convictions but those who are caught with large amounts, growing or dealing cannabis still do. No country has legalised all drug use, but Portugal has decriminalised possession of all drugs and penalties for personal possession of all drugs are generally decreasing throughout Europe.

No country has legalised all drug use but Portugal has decriminalised possession of all drugs

A change in cannabis policy has the potential to affect wider drug policies. If legalisation of cannabis reduces negative outcomes and demonstrates a more effective balance between law enforcement and public health objectives, it may gradually result in countries being more open to extending this approach to other drugs.[1] Monitoring the impacts of cannabis legalisation will be crucial in determining whether that is appropriate. Importantly, popular support is a large driver of cannabis law reform globally and such wide support does not currently exist for other drugs.

 

[1] Hughes et al., “Could Cannabis Liberalisation Lead to Wider Changes in Drug Policies and Outcomes?,” International Journal of Drug Policy 51 (2018)

If cannabis is legal, will it be a gateway to other drugs?

People use drugs for complex reasons. The pathway to drug use is not as simple as one being a gateway to using other illicit substances. That said, legalising cannabis has the potential to impact people’s use of other illegal substances in a few different ways.

  • Legalising cannabis can disconnect cannabis purchase from the illegal market. Throughout Aotearoa New Zealand, methamphetamine is currently more available than cannabis. It is thought that dealers favour selling methamphetamine because it is more profitable.[1] Providing a way to purchase cannabis that is disconnected from the illegal market may reduce exposure to other drugs, including methamphetamine. In the Netherlands, there is little or no evidence of a gateway effect between cannabis and cocaine despite cannabis being available for purchase from coffeeshops since the 1970s.[2]
  • Regular use of cannabis might make people want to try other psychoactive substances. Most people who use cannabis do not progress to use of other illegal drugs, but people who use cannabis often are more likely to use other drugs.[3] This can be partly explained by people being more interested in trying other psychoactive substances after using cannabis, but may also be related to contact with the illegal market (discussed above) and social and personal factors that drive drug use.

Legal cannabis may not necessarily reduce use of synthetic cannabis. It is possible that the availability of legal cannabis would reduce the use of synthetic cannabis, but given that some of the reasons for using synthetic cannabis include the cheaper price and it not being picked up on routine drug tests, it is not guaranteed.[4]

 

[1] Wilkins et al., “Determinants of High Availability of Methamphetamine, Cannabis, Lsd and Ecstasy in New Zealand: Are Drug Dealers Promoting Methamphetamine Rather Than Cannabis?,” International Journal of Drug Policy 61 (2018)

[2] Van Ours, “Is Cannabis a Stepping-Stone for Cocaine?,” Journal of Health Economics 22, no. 4 (2003)

[3] Anthony, “Steppingstone and Gateway Ideas: A Discussion of Origins, Research Challenges, and Promising Lines of Research for the Future,” Drug Alcohol Depend 123 Suppl 1 (2012); Fergusson et al., “Cannabis and Psychosis,” BMJ 332, no. 7534 (2006); MacCoun, “In What Sense (If Any) Is Marijuana a Gateway Drug,” FAS Drug Policy Analysis Bulletin 4 (1998); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[4] Gunderson et al., “A Survey of Synthetic Cannabinoid Consumption by Current Cannabis Users,” Substance Abuse 35, no. 2 (2014); Martz et al., “Rates of Synthetic Cannabinoid Use in Adolescents Admitted to a Treatment Facility,” The primary care companion for CNS disorders 20, no. 5 (2018)

What is cannabis?

Cannabis used for non-medical purposes commonly exists as either a resin (called hashish in the United States) or as dry herbal material. The resin is made by compressing resin glands from the plant. The dried plant material is dried flowers and fruits and some leaves and stems of the female cannabis plant.  The plant can be processed into a number of products including oils, concentrates and extracts.

Cannabis contains more than 120 chemicals known as cannabinoids. Experts still aren’t sure what each cannabinoid does, but two are relatively well-studied – CBD (cannabidiol) and THC (Δ9-tetrahydrocannabinol), with THC being the most studied. CBD is a non-intoxicating cannabinoid and THC is the main psychoactive compound that is responsible for the ‘high’ feeling.[1] In the plant, THC and CBD exist in their acid form (THC-A, or CBD-A), which get converted to THC or CBD on heating or drying. The combined effect of CBD and THC is complex and not well understood, but it is known that the ratio is important because CBD reduces some of the more negative aspects of THC, including anxiety and unpleasant psychosis.[2] Levels of THC and CBD vary depending on the plant strain and growing conditions. The strength of cannabis has been steadily increasing on the illegal market through the breeding of plants to increase the THC content, lower the CBD content, or make the ratio of THC to CBD higher.[3]

When cannabis is smoked, THC (and other chemicals) pass from the lungs to the blood, which carries them rapidly throughout the body to the brain. Effects are felt quickly. When cannabis is eaten, the effects are delayed by 30-60 minutes as the body digests the food or drink. This delay may cause some people to eat more THC, leading to a higher dose than planned. The noticeable effects of cannabis last about 1-3 hours if smoked and can last for many hours when eaten. Cannabinoids can stay stored in the body for periods lasting weeks or more, which has implications for drug testing.

See ‘Is all cannabis use harmful? and ‘How might legalisation change the health impacts of cannabis?’

 

[1] Devinsky et al., “Cannabidiol: Pharmacology and Potential Therapeutic Role in Epilepsy and Other Neuropsychiatric Disorders,” Epilepsia 55, no. 6 (2014); Banister et al., “Dark Classics in Chemical Neuroscience: Delta(9)-Tetrahydrocannabinol,” Acs Chemical Neuroscience 10, no. 5 (2019); Di Marzo, “New Approaches and Challenges to Targeting the Endocannabinoid System (Vol 17, Pg 623, 2018),” Nature Reviews Drug Discovery 17, no. 9 (2018)

[2] Boggs et al., “Clinical and Preclinical Evidence for Functional Interactions of Cannabidiol and Delta(9)-Tetrahydrocannabinol,” Neuropsychopharmacology 43, no. 1 (2018); Di Forti et al., “High-Potency Cannabis and the Risk of Psychosis,” British Journal of Psychiatry 195, no. 6 (2009)

[3] Chandra et al., “New Trends in Cannabis Potency in USA and Europe During the Last Decade (2008-2017) (Vol 269, Pg 5, 2019),” European Archives of Psychiatry and Clinical Neuroscience 269, no. 8 (2019)

Will cannabis use increase if it is legalised?

It is very common to have tried cannabis and common to occasionally use cannabis even though it is illegal. Most people have tried cannabis at some point in their lives and 15% of people reported using cannabis in the past year in 2018/19.[1] It is not clear how rates of cannabis use would change if recreational use is legalised but it is reasonable to expect that legalisation will ‘normalise’ cannabis use in society. Exact changes depend on whether non-users begin to use cannabis upon legalisation, and whether existing users change their patterns of use. In turn, regulation of the legal market and the price of legal cannabis will impact use patterns. The regulation will dictate where, how much and what types of cannabis can be accessed legally.

It is very common to have tried cannabis and common to occasionally use cannabis even though it is illegal

Through studies and surveys conducted locally, we know that despite cannabis being illegal:

There are only a small number of studies to date measuring the impacts on rates of use where cannabis has been legalised. These short-term effects may not reflect longer-term trends. This is because the legal retail environment is only recently established in most places, so the impact of legalisation is lagging behind the law change. Some studies are also limited in how they measure ‘use’, commonly looking at whether someone used cannabis in the past month or year which may not reflect problematic use that leads to increased harm. Use trends differ by age, gender and location so there are no blanket findings about cannabis use following legalisation.

Use trends differ by age, gender and location so there are no blanket findings about cannabis use following legalisation

So far, the evidence from overseas shows that in the short term:

There are only a small number of studies to date measuring the impacts on rates of use where cannabis has been legalised. These short-term effects may not reflect longer-term trends

It is too early to tell what the impact of legalisation on use rates will be and we are unlikely to know long-term outcomes on patterns of use for some time. For context, it took four decades for alcohol consumption to return to pre-prohibition levels in the US.[25]

We also need to interpret cannabis use data with caution. Because it is illegal, research on cannabis has historically been difficult and there are real concerns about collecting and storing data on who uses cannabis and where they get it from. People may also be reluctant to be honest about their use of cannabis when it is illegal but more willing to report use when it becomes legal. This makes it look like use has increased following legalisation, though it doesn’t explain differential changes among different subgroups. Alternative methods of testing cannabis use such as through wastewater testing, as was done in Washington State,[26] could get around these issues. In Aotearoa New Zealand, ESR is working with the police on testing for drugs in wastewater, but cannabis is not currently included.

Public health impacts are related to problematic use of cannabis rather than occasional use, so health impacts depend on who is using cannabis and how often – see ‘Is all cannabis use harmful?

 

[1] Ministry of Health, “New Zealand Health Survey: Annual Data Explorer”, 2019

[2] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015

[3] Boden et al., “Illicit Drug Use and Dependence in a New Zealand Birth Cohort,” Australian & New Zealand Journal of Psychiatry 40, no. 2 (2006)

[4] Ministry of Health, “New Zealand Health Survey: Annual Data Explorer”, 2019

[5] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015

[6] Howard et al., “Alcohol, Cannabis and Amphetamine‐Type Stimulants Use among Young Pacific Islanders,” Drug and alcohol review 30, no. 1 (2011)

[7] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015; Fergusson et al., “Psychosocial Sequelae of Cannabis Use and Implications for Policy: Findings from the Christchurch Health and Development Study,” Social Psychiatry and Psychiatric Epidemiology 50, no. 9 (2015)

[8] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015

[9] Ball et al., “Declining Adolescent Cannabis Use Occurred across All Demographic Groups and Was Accompanied by Declining Use of Other Psychoactive Drugs, New Zealand, 2001–2012,” New Zealand Medical Journal 132, no. 1500 (2019); Jude Ball, “Adolescent Cannabis Use Continues Its Downward Trend, New Zealand 2012–2018,” New Zealand Medical Journal 133, no. 1510 (2020)

[10] Lenton, “Cannabis Policy and the Burden of Proof: Is It Now Beyond Reasonable Doubt That Cannabis Prohibition Is Not Working?,” Drug and Alcohol Review 19, no. 1 (2000)

[11] Badiani et al., “Tobacco Smoking and Cannabis Use in a Longitudinal Birth Cohort: Evidence of Reciprocal Causal Relationships,” Drug and Alcohol Dependence 150 (2015)

[12] Winstock et al., “Global Drug Survey 2019-Key Findings Report”, 2019

[13] Rotermann, “What Has Changed since Cannabis Was Legalized?” Health reports 31, no. 2 (2020)

[14] Kerr et al., “Changes in Marijuana Use across the 2012 Washington State Recreational Legalization: Is Retrospective Assessment of Use before Legalization More Accurate?,” Journal of Studies on Alcohol and Drugs 79, no. 3 (2018); 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)

[15] Kerr et al., “Oregon Recreational Marijuana Legalization: Changes in Undergraduates’ Marijuana Use Rates from 2008 to 2016,” Psychology of Addictive Behaviors 32, no. 6 (2018)

[16] 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)

[17] de Drogas, “Vi Encuesta Nacional En Hogares Sobre Consumo De Drogas, 2016,” Informe de investigación (2018)

[18] 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); 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)

[19] 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)

[20] Rotermann, “What Has Changed since Cannabis Was Legalized?” Health reports 31, no. 2 (2020)

[21] 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)

[22] Rotermann, “What Has Changed since Cannabis Was Legalized?” Health reports 31, no. 2 (2020); 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); Cerdá et al., “Association of State Recreational Marijuana Laws with Adolescent Marijuana Use,” JAMA Pediatrics 171, no. 2 (2017); Dilley et al., “Prevalence of Cannabis Use in Youths after Legalization in Washington State,” JAMA Pediatrics 173, no. 2 (2019); Melchior et al., “Does Liberalisation of Cannabis Policy Influence Levels of Use in Adolescents and Young Adults? A Systematic Review and Meta-Analysis,” BMJ Open 9, no. 7 (2019); 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); Mennis et al., “Adolescent Treatment Admissions for Marijuana Following Recreational Legalization in Colorado and Washington,” Drug and Alcohol Dependence 210 (2020)

[23] Laqueur et al., “The Impact of Cannabis Legalization in Uruguay on Adolescent Cannabis Use,” International Journal of Drug Policy 80 (2020)

[24] Looze et al., “Decreases in Adolescent Weekly Alcohol Use in Europe and North America: Evidence from 28 Countries from 2002 to 2010,” The European Journal of Public Health 25, no. suppl_2 (2015)

[25] 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)

[26] Burgard et al., “Using Wastewater‐Based Analysis to Monitor the Effects of Legalized Retail Sales on Cannabis Consumption in Washington State, USA,” Addiction 114, no. 9 (2019)

What is cannabis use disorder?

Doctors use the term ‘cannabis use disorder’ to describe problematic use of cannabis, ranging from mild to severe, with addiction at the severe end of the spectrum. Cannabis use disorder can lead to a person suffering from anxiety, sleeping problems, depression and appetite changes when they stop using it. People who use cannabis have a 1 in 5 risk of developing cannabis use disorder, with risk increasing for those who use cannabis early, often, and use more potent cannabis.[1] But use alone does not determine if someone will develop problematic use of cannabis – other personal, environmental and social factors will contribute.

 

[1] Lichtman et al., Cannabinoid Tolerance and Dependence (Springer, 2005); Leung et al. “What is the prevalence and risk of cannabis use disorders among people who use cannabis? A systematic review and meta-analysis.” Addictive Behaviors (2020)

Is all cannabis use harmful?

Illegal cannabis use is common and the majority of people who use cannabis have not experienced harms from their use. But the consequences of using cannabis aren’t the same for everyone.[1] Certain people or those with particular patterns of use are more likely to be harmed – either because of health impacts from using cannabis (see below) or because cannabis is illegal and using it has got them in trouble with the law (referred to as ‘social’ harm – see ‘What are the social and community impacts of cannabis prohibition?’). Cannabis also comes in a variety of forms and strengths – some are less harmful than others – see ‘What is cannabis?’

The consequences of using cannabis aren’t the same for everyone

Most health-related harm is suffered by those who use cannabis young, at high potency and on most days – this harm happens whether or not cannabis is legal. Lower-risk cannabis use guidelines have been developed by researchers based on evidence of the least harmful approaches to cannabis use.[15] Questions have been raised about the likelihood of people following these guidelines as there is currently little or no support for addiction treatment and education to steer people towards lower-risk use of cannabis.[16] The strategies to reduce harm include:

  1. Choosing not to use cannabis
  2. Not starting to use cannabis until after 25
  3. Using cannabis products with a low THC content or higher CBD:THC ratio
  4. Not using synthetic cannabis products
  5. Using non-smoking options to consume cannabis
  6. If smoking, avoiding deep inhalation and long holding of the breath
  7. Minimising use as much as possible
  8. Not driving or operating machinery while impaired
  9. Completely avoiding cannabis use if you have a personal or family history of psychosis, substance use problems, or are pregnant
  10. Avoid combining behaviours that are considered higher-risk

 See ‘How might legalisation change the health impacts of cannabis?’

 

[1] Fergusson et al., “Psychosocial Sequelae of Cannabis Use and Implications for Policy: Findings from the Christchurch Health and Development Study,” Social Psychiatry and Psychiatric Epidemiology 50, no. 9 (2015); Silins et al., “Young Adult Sequelae of Adolescent Cannabis Use: An Integrative Analysis,” Lancet Psychiatry 1, no. 4 (2014); Anthony, “The Epidemiology of Cannabis Dependence,” Cannabis dependence: Its nature, consequences and treatment  (2006); van der Pol et al., “Predicting the Transition from Frequent Cannabis Use to Cannabis Dependence: A Three-Year Prospective Study,” Drug and Alcohol Dependence 133, no. 2 (2013); Budney et al., “The Cannabis Withdrawal Syndrome,” Curr Opin Psychiatry 19, no. 3 (2006); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[2] Fergusson et al., “Psychosocial Sequelae of Cannabis Use and Implications for Policy: Findings from the Christchurch Health and Development Study,” Social Psychiatry and Psychiatric Epidemiology 50, no. 9 (2015); Silins et al., “Young Adult Sequelae of Adolescent Cannabis Use: An Integrative Analysis,” Lancet Psychiatry 1, no. 4 (2014); Anthony, “The Epidemiology of Cannabis Dependence,” Cannabis dependence: Its nature, consequences and treatment  (2006); van der Pol et al., “Predicting the Transition from Frequent Cannabis Use to Cannabis Dependence: A Three-Year Prospective Study,” Drug and Alcohol Dependence 133, no. 2 (2013); Budney et al., “The Cannabis Withdrawal Syndrome,” Curr Opin Psychiatry 19, no. 3 (2006); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[3] Patton et al., “Cannabis Use and Mental Health in Young People: Cohort Study,” British Medical Journal 325, no. 7374 (2002); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[4] Wilkins et al., “Determinants of the Retail Price of Illegal Drugs in New Zealand,” International Journal of Drug Policy 79 (2020)

[5] Hall et al., “High Potency Cannabis”, British Medical Journal 350 (2015)

[6] Sheehan et al., “Chemical and Physical Variations of Cannabis Smoke from a Variety of Cannabis Samples in New Zealand,” Forensic Sciences Research 4, no. 2 (2019)

[7] Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017)

[8] Gracie et al., “Cannabis Use Disorder and the Lungs,” Addiction (2020)

[9] 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); Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017)

[10] Zipursky et al., “Edible Cannabis,” Canadian Medical Association Journal 192, no. 7 (2020)

[11] 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)

[12] Degenhardt et al., “Cannabis and Psychosis,” Current Psychiatry Reports 4, no. 3 (2002); Caspi et al., “Moderation of the Effect of Adolescent-Onset Cannabis Use on Adult Psychosis by a Functional Polymorphism in the Catechol-O-Methyltransferase Gene: Longitudinal Evidence of a Gene X Environment Interaction,” Biological Psychiatry 57, no. 10 (2005); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[13] Metz et al., “Marijuana Use in Pregnancy and Lactation: A Review of the Evidence,” American Journal of Obstetrics and Gynecology 213, no. 6 (2015); Gunn et al., “Prenatal Exposure to Cannabis and Maternal and Child Health Outcomes: A Systematic Review and Meta-Analysis,” BMJ Open 6, no. 4 (2016)

[14] Volkow et al., “Adverse Health Effects of Marijuana Use,” New England Journal of Medicine 370, no. 23 (2014)

[15] Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017)

[16] Caulkins et al., “Lower-Risk Cannabis Use Guidelines: Will Users Listen?,” American Journal of Public Health 110, no. 1 (2019)

How might legalisation change the health impacts of cannabis?

The health impacts of cannabis use aren’t the same for everyone. Some can be beneficial and some harmful.[1] It depends on who is using it, what they are using it for and how often. The health impacts also depend on the type of cannabis being used. Cannabis is variable – it comes in different strengths and products, different parts of the plant can be consumed, and sometimes it is combined with other substances. Cannabis use has health impacts regardless of whether it is legal or illegal, but the impacts may change depending on how the legal market is regulated.

Cannabis use has health impacts regardless of whether it is legal or illegal, but the impacts may change depending on how the legal market is regulated

  • Trying cannabis is unlikely to cause harm, but ongoing use can have negative health impacts. As well as the intoxicating effects experienced immediately after use, heavy cannabis use can have a range of health impacts. Research into the health impacts of cannabis has been limited by its illegal status and it is difficult to assess the adverse health impacts that are specifically caused by cannabis. What we do know has been summarised by the Royal Society Te Apārangi in Cannabis: How it affects our health. In short:
    • Cannabis use can be addictive but most people don’t become addicted.
    • Cannabis use can alter brain development. This can occur for people who start using cannabis regularly or intensively early in adolescence while the brain is still developing, but can change back after time without use.[2] Regular use over a long time can also lead to reduced memory and attention span.[3]
    • Smoking cannabis can cause lung damage. People who smoke cannabis may experience symptoms of chronic bronchitis and other respiratory symptoms such as cough and wheeze.[4]
    • Cannabis use can increase the risk of psychotic symptoms or psychosis in some people. Cannabis can contribute to psychotic symptoms – when people experience changes in how they perceive reality and find it hard to know what is real – but most people that use cannabis do not experience these symptoms and most cases are not caused by cannabis.[5] Psychotic symptoms associated with cannabis use are often very mild.[6] Cannabis can also contribute to more serious psychotic illness and the risk of this outcome is substantially increased for people who start using cannabis young, often and in more potent forms.[7] Around one in ten people who started using cannabis before they were 15 will go on to develop psychosis by age 26, and it is more likely for those who used it often.[8] People with psychosis who keep using cannabis have a worse prognosis than those who stop using it.[9] The risk is higher for people who have a family history of psychotic illness. Part of the link might also be explained by people suffering from psychosis being drawn to using cannabis.[10]
    • There is a weak association between cannabis use and depression. This could suggest a causal link or could be explained by people with depression being more likely to use cannabis.[11] We cannot draw a definitive conclusion about the direction of effect.
  • Changes in rates of use may impact the prevalence of these health conditions.
  • Potency limits may reduce some negative health impacts. The more potent the cannabis, the more likely it is to cause health-related harms. In the illicit market, cannabis potency has been steadily increasing.[12] For example in the illicit market in the USA, the average THC level from seized cannabis increased from around 4% in 1996 to around 17% in 2017, with an increase in THC:CBD ratio from 23 to 104.[13] The proposed regulation includes a limit on THC of 15% for dried plant material, which is thought to be the upper end of the illegal market in Aotearoa New Zealand, though there is limited data on this.[14] We would expect a range of low THC and high CBD to also be available. The THC limit needs to strike a balance between reducing harm and drawing users away from the illegal market. A potential consequence of a lower limit is that it could maintain an illegal market for higher potency cannabis. Limits on other products are yet to be determined, but provisions for concentrates also indicate higher-strength cannabis would be available. Stronger cannabis could still be grown through home grow provisions in the law.
  • Age restrictions may limit young people using cannabis, but could lead to them accessing illicit cannabis instead. Preventing people under 20 from using cannabis would reduce the negative health impacts associated with adolescent use. Though the number of young teenagers trying cannabis has been declining in recent years, young people up to age 25 are still the highest users of cannabis.
  • Public health messaging and education may help to promote lower-risk use. A benefit of legalising cannabis is that it becomes easier to educate the public about the risks and harms associated with cannabis use, including public health messaging about who might be more likely to be harmed from use. Because of the increased harm from adolescent use, specific preventative programmes aimed at school-age children may reduce harm.
  • If legal, there may be better access to health services that can support people with cannabis addiction.

 

[1] Royal Society Te Apārangi, “Cannabis: How It Affects Our Health,” (2019); Russell et al., “Routes of Administration for Cannabis Use – Basic Prevalence and Related Health Outcomes: A Scoping Review and Synthesis,” International Journal of Drug Policy 52 (2018); Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017); Solowij et al., “Cognitive Functioning of Long-Term Heavy Cannabis Users Seeking Treatment,” JAMA 287, no. 9 (2002); Solowij et al., “Cannabis and Cognition: Short and Long-Term Effects,” Marijuana and Madness 2 (2012); Solowij et al., “Verbal Learning and Memory in Adolescent Cannabis Users, Alcohol Users and Non-Users,” Psychopharmacology 216, no. 1 (2011)

[2] Lorenzetti et al., “Adolescent Cannabis Use, Cognition, Brain Health and Educational Outcomes: A Review of the Evidence”. European Neuropsychopharmacology (2020); Kroon et al., “Heavy Cannabis Use, Dependence and the Brain: A Clinical Perspective,” Addiction 115, no. 3 (2020)

[3] Solowij et al., “Cognitive Functioning of Long-Term Heavy Cannabis Users Seeking Treatment,” JAMA 287, no. 9 (2002)

[4] Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020); Gracie et al., “Cannabis Use Disorder and the Lungs,” Addiction (2020)

[5] Volkow et al., “Adverse Health Effects of Marijuana Use,” New England Journal of Medicine 370, no. 23 (2014); Hall et al., “Adverse Health Effects of Non-Medical Cannabis Use,” The Lancet 374, no. 9698 (2009); Karila et al., “Acute and Long-Term Effects of Cannabis Use: A Review,” Current Pharmaceutical Design 20, no. 25 (2014); Degenhardt et al., “The Global Epidemiology and Contribution of Cannabis Use and Dependence to the Global Burden of Disease: Results from the Gbd 2010 Study,” PLOS ONE 8, no. 10 (2013); Hall, “What Has Research over the Past Two Decades Revealed About the Adverse Health Effects of Recreational Cannabis Use?,” Addiction 110, no. 1 (2015); Volkow et al., “Effects of Cannabis Use on Human Behavior, Including Cognition, Motivation, and Psychosis: A Review,” JAMA Psychiatry 73, no. 3 (2016); Broyd et al., “Acute and Chronic Effects of Cannabinoids on Human Cognition—a Systematic Review,” Biological Psychiatry 79, no. 7 (2016); Scott et al., “Association of Cannabis with Cognitive Functioning in Adolescents and Young Adults: A Systematic Review and Meta-Analysis,” JAMA Psychiatry 75, no. 6 (2018); Fergusson et al., “Cannabis and Psychosis,” BMJ 332, no. 7534 (2006); Poulton et al., “Patterns of Recreational Cannabis Use in Aotearoa-New Zealand and Their Consequences: Evidence to Inform Voters in the 2020 Referendum,” Journal of the Royal Society of New Zealand (2020)

[6] Pearson et al., “Cannabis and Psychosis through the Lens of Dsm-5,” International Journal of Environmental Research and Public Health 16, no. 21 (2019)

[7] Murray et al., “Will Legalization and Commercialization of Cannabis Use Increase the Incidence and Prevalence of Psychosis?,” JAMA Psychiatry  (2020)

[8] Arseneault et al., “Cannabis Use in Adolescence and Risk for Adult Psychosis: Longitudinal Prospective Study,” BMJ 325, no. 7374 (2002); McLaren et al., “Assessing Evidence for a Causal Link between Cannabis and Psychosis: A Review of Cohort Studies,” International Journal of Drug Policy 21, no. 1 (2010)

[9] Murray et al., “Will Legalization and Commercialization of Cannabis Use Increase the Incidence and Prevalence of Psychosis?,” JAMA Psychiatry (2020)

[10] Fergusson et al., “Cannabis and Psychosis,” BMJ 332, no. 7534 (2006)

[11] Fergusson et al., “Tests of Causal Linkages between Cannabis Use and Psychotic Symptoms,” Addiction 100, no. 3 (2005); Rey et al., “Mental Health of Teenagers Who Use Cannabis: Results of an Australian Survey,” The British Journal of Psychiatry 180, no. 3 (2002); Arseneault et al., “Cannabis Use in Adolescence and Risk for Adult Psychosis: Longitudinal Prospective Study,” BMJ 325, no. 7374 (2002)

[12] Wilkins et al., “Cannabis and Other Illicit Drug Trends in New Zealand, 2005,” Auckland, Massey University (2005)

[13] Chandra et al., “New Trends in Cannabis Potency in USA and Europe During the Last Decade (2008-2017) (Vol 269, Pg 5, 2019),” European Archives of Psychiatry and Clinical Neuroscience 269, no. 8 (Dec 2019)

[14] Sheehan et al., “Chemical and Physical Variations of Cannabis Smoke from a Variety of Cannabis Samples in New Zealand,” Forensic Sciences Research 4, no. 2 (2019)

Will legalising cannabis burden the healthcare system?

A key goal of legalising cannabis is to shift cannabis use towards ‘health issue’ and away from ‘criminal issue’. This can be achieved by reducing harm caused by problematic use of cannabis and lowering the use of cannabis over time through education and addiction services. Because of this, legalising cannabis could change demands on the healthcare system for addiction services, emergency needs and longer-term health needs.

Legalising cannabis could change demands on the healthcare system for addiction services, emergency needs and longer-term health needs

 

[1] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015

[2] Vogl et al., “A Universal Harm-Minimisation Approach to Preventing Psychostimulant and Cannabis Use in Adolescents: A Cluster Randomised Controlled Trial,” Substance Abuse Treatment, Prevention, and Policy 9, no. 1 (2014)

[3] Walker, “Issues of Tobacco, Alcohol and Other Substance Abuse for Māori”, 2019; Theodore et al., “Cannabis, the Cannabis Referendum and Māori Youth: A Review from a Lifecourse Perspective,” Kōtuitui: New Zealand Journal of Social Sciences Online (2020)

[4] Walker, “Issues of Tobacco, Alcohol and Other Substance Abuse for Māori”, 2019

[5] Benfer et al., “The Impact of Drug Policy Liberalisation on Willingness to Seek Help for Problem Drug Use: A Comparison of 20 Countries,” International Journal of Drug Policy 56 (2018)

[6] 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)

[7] Hall et al., Cannabis Use and Dependence: Public Health and Public Policy (Cambridge University Press, 2003); European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), “Table Tdi-105, Part Vii: All Clients Entering Inpatient Treatment by Primary Drug and Age, 2009 or Most Recent Year Available: All Cannabis Inpatient Clients by Country and Age.”, 2011; World Health Organization, Atlas on Substance Use (2010): Resources for the Prevention and Treatment of Substance Use Disorders (Geneva, 2010); Roxburgh et al., “The Epidemiology of Cannabis Use and Cannabis‐Related Harm in Australia 1993–2007,” Addiction 105, no. 6 (2010)

[8] 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)

[9] 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); Kim et al., “Colorado Cannabis Legalization and Its Effect on Emergency Care,” Annals of Emergency Medicine 68, no. 1 (2016); Wang et al., “Marijuana and Acute Health Care Contacts in Colorado,” Prev Med 104 (2017)

Will there be more accidents if cannabis is legalised?

Motor vehicle and workplace accidents are important public health issues related to cannabis use and are an issue even when cannabis is illegal. In Aotearoa New Zealand, around one in three people who use cannabis reported driving under the influence of cannabis in the past year.[1] How cannabis-impaired driving might change following legalisation for recreational use is not clear and depends on the rules and testing for cannabis-impaired driving, which are not covered in the proposed bill – see ‘What happens if you get caught with cannabis now? How would it change?’

In Aotearoa New Zealand, around one in three people who use cannabis reported driving under the influence of cannabis in the past year

Cannabis affects each person differently – the level of impairment depends on how much cannabis is consumed, how it is consumed (smoked, inhaled, ingested), how much, how strong it is and the user’s physiology. Because of the illegal status of cannabis, research to understand its impacts on driving impairment has been difficult. As a result, there is no guidance to drivers about how much cannabis can be consumed before it is unsafe to drive or how long to wait to drive after consuming cannabis. There is a small (1.3–3 fold) increased risk of motor vehicle accidents with cannabis use, with risk increasing in a dose-related way for stronger cannabis (higher THC concentration) or frequency of use.[2] In comparison, a person aged 30 and above is about 5.8 times more likely to be involved in a fatal crash at the legal blood alcohol limit compared to a blood alcohol reading of zero, with the risk increasing for younger people and in a dose-related way.[3] The risk is substantially higher when cannabis and alcohol are combined.[4]

There is conflicting evidence about the impact on traffic fatalities where cannabis has been legalised overseas, partly because of limited data and partly because there may be increased testing for cannabis after a motor vehicle accident once it is legalised.[5] For example, two studies found no effect of legalised recreational cannabis on traffic fatalities,[6] two more recent studies found fatal crash rates increased after stores opened[7] and another study found conflicting results between two different states.[8] A non-peer-reviewed study found that legalisation of retail sales of cannabis was associated with an increase in auto insurance collision claims.[9]

There is conflicting evidence about the impact on traffic fatalities where cannabis has been legalised overseas

There are two main ways these studies have been done so far. One way is researchers testing whether there are correlations between, for example, the number of car accidents and the timing of the law change. The limitation with this approach is that the drivers are not actually tested to see if they had used cannabis so the results could be caused or influenced by something other than cannabis. The other way is to test for the presence of cannabis (specifically THC) in the blood of drivers who crash. This method is still limited because it doesn’t actually test how impaired the driver was at the time of the crash and doesn’t take into account who was at fault in the crash. Because of the limitations in how these studies are done, all research into car accidents and cannabis legalisation should be interpreted with caution.

Because of inherent limitations in studies relating to impairment, the same caution should be applied to studies of cannabis use and workplace accidents.

 

[1] Ministry of Health, “Cannabis Use 2012/13: New Zealand Health Survey”, 2015

[2] Li et al., “Marijuana Use and Motor Vehicle Crashes,” Epidemiologic Reviews 34, no. 1 (2012); Poulsen, “Alcohol and Other Drug Use in New Zealand Drivers 2004 to 2009,” Wellington, New Zealand: New Zealand Police (2010); Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017)

[3] Ministry of Transport, “Alcohol and Drugs 2017”, 2017

[4] Li et al., “Marijuana Use and Motor Vehicle Crashes,” Epidemiologic Reviews 34, no. 1 (2012); Fischer et al., “Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations,” American Journal of Public Health 107, no. 8 (2017)

[5] 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 (2019/12/01 2019); Nazif-Munoz et al., “The Association between Legalisation of Cannabis Use and Traffic Deaths in Uruguay,” Addiction (2020); Tefft et al., “Cannabis Use among Drivers in Fatal Crashes in Washington State before and after Legalization”, 2020; Tefft et al., “Prevalence of Marijuana Involvement in Fatal Crashes: Washington, 2010–2014”, 2016; Lane et al., “Traffic Fatalities within US States That Have Legalized Recreational Cannabis Sales and Their Neighbours,” Addiction 114, no. 5 (2019); Aydelotte et al., “Fatal Crashes in the 5 Years after Recreational Marijuana Legalization in Colorado and Washington,” Accident Analysis & Prevention 132 (2019); Aydelotte et al., “Crash Fatality Rates after Recreational Marijuana Legalization in Washington and Colorado,” American Journal of Public Health 107, no. 8 (2017); Hansen et al., “Early Evidence on Recreational Marijuana Legalization and Traffic Fatalities,” Economic Inquiry (2018); 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.

[6] Aydelotte et al., “Crash Fatality Rates after Recreational Marijuana Legalization in Washington and Colorado,” American Journal of Public Health 107, no. 8 (2017)

[7] Aydelotte et al., “Fatal Crashes in the 5 Years after Recreational Marijuana Legalization in Colorado and Washington,” Accident Analysis & Prevention 132 (2019)

[8] Santaella-Tenorio et al. “Association of Recreational Cannabis Laws in Colorado and Washington State with Changes in Traffic Fatalities, 2005-2017”. JAMA Internal Medicine (2020)

[9] Highway Loss Data Institute, “Recreational Marijuana and Collision Claim Frequencies,” HLDI Bulletin 35, no. 8 (2018)

How much revenue would the Government make if cannabis was legal?

Estimates of the potential revenue from a legal cannabis market in Aotearoa New Zealand need to be interpreted with caution because many estimates were made prior to the details of the parameters for taxes, levies and licensing fees being shared in the final draft bill. All estimates also depend on the size of the market, which is uncertain. Rather than being a profit-making enterprise for the government, it is more helpful to consider that a legal framework will allow for more meaningful spending associated with cannabis use – shifting from enforcement costs to health-related costs.

  • The government cannot source revenue from cannabis sales while it is illegal. Under prohibition, it is impossible to generate tax revenue or benefit from economic development from cannabis production or sales.
  • A legal market can generate revenue for the government through taxes. The amount of revenue from a legal cannabis market depends on total sales and the way the government taxes sales. If tax is a proportion of the sale, tax revenue would decrease as the price of cannabis decreases unless this is offset by an increase in total sales. The taxation level and price of legal products will be critical factors in the extent to which consumers shift from illegal to legal retail sources.[1]
  • Spending on enforcement currently outweighs spending on harm reduction. Under prohibition, the government spends substantially more on cannabis enforcement than cannabis-focused prevention or professional help (e.g. treatment) services through the health system. It is possible these spending patterns could change under prohibition if enforcement lessened.
  • There will be new and different costs associated with a legal market. The development of infrastructure and administration to regulate cannabis and improved health services will require additional expenditures. Enforcement of remaining offences also carries a cost.
  • Health resources for cannabis users could be supported more meaningfully under a legal framework. Legalisation provides an opportunity to save money on expenditures for enforcement of prohibition and generate tax revenue from cannabis production or sales. This revenue could be directed to health-oriented and harm-reduction measures related to cannabis.

 

[1] Hammond et al., “Evaluating the Impacts of Cannabis Legalization: The International Cannabis Policy Study,” International Journal of Drug Policy 77 (2020)

Cannabis law reform: overseas experiences

Cannabis law reform is taking place across the world. Many countries have taken steps to decriminalise cannabis use or to legalise medicinal use of cannabis. Very recently, a few countries and states have legalised recreational use of cannabis.

Status of cannabis law reform for recreational cannabis use worldwide. Image credit: Jamesy0627144/Wikimedia CC BY-SA 4.0. Various jurisdictions have legalised recreational cannabis, including states in the US, Canada, Uruguay, ACT (Australia) and South Africa. For ACT and South Africa, there is no commercial market or way to purchase cannabis through regulated stores, only home grow is allowed. In contrast, the other places that have legalised cannabis allow for purchase, with Uruguay having a government-controlled market, most US states having commercial markets, and Canada having a commercial market with tighter regulation.

 

Research to understand the impacts of these policy changes on public health, public safety, youth and social outcomes is underway and ongoing, but there is insufficient evidence to draw firm conclusions. The limited evidence from overseas examples is mixed and constantly evolving – outcomes from early studies appear to be both positive and negative.

There are many knowledge gaps and limitations in our understanding of the impacts of cannabis legalisation and commercialisation. The biggest issue is that because cannabis has been legalised for recreational use so recently it is difficult to draw conclusions about the potential effects. We also need to interpret available data with caution. There is sometimes a considerable delay between the law changing and the changes being implemented, which means a simplistic look at the data can lead to incorrect conclusions. Changes to the legal status of cannabis might mean that people are more likely to report use in surveys or to healthcare workers, possibly making cannabis use appear to increase when it has not.

Legalisation

New Zealanders are voting whether to legalise cannabis at the upcoming referendum. In general, it is too early to tell the full effects of cannabis legalisation and we are unlikely to know these for decades. Even in the future, we may be limited in drawing firm conclusions about the effects of legalising and commercialising cannabis due to the lack of historical data. Nevertheless, lessons can be learned from early adopters, including Uruguay, Canada and some states in the US.​

Decriminalisation

New Zealanders are NOT voting to decriminalise cannabis at the upcoming referendum. However, decriminalisation has been in practice in some jurisdictions for a long time and can give some insight into the impacts of taking the threat of criminal justice out of using cannabis. This includes the Netherlands, Australia, Spain and Portugal.

Uruguay: A government-controlled market

The Uruguayan government legalised recreational use of cannabis in 2013. Uruguayan citizens (not tourists) who are 18 years or older and want legal cannabis have to register for use and choose either home growing, cannabis social clubs or purchasing from an authorised pharmacy.

United States: An open, commercial approach that varies by state

Eleven states have legalised recreational cannabis use, though cannabis remains prohibited under federal law. For many states this followed establishment of a medicinal cannabis market and previous decriminalisation of cannabis use. In most states with a legal cannabis market, products can be purchased in unlimited strengths and forms from retail stores.

Spain: Decriminalised non-profit distribution model

Some parts of Spain have taken a liberal approach to cannabis regulation since the 1970s. Grey areas in the legislation meant that cannabis social clubs emerged in the early 2000s, producing cannabis for non-profit distribution solely to a closed group of adult members. These non-commercial organisations do not have specific formal regulation or nation-wide criteria, but certain areas have enforced regulation of some aspects of cannabis social clubs.

Portugal: Decriminalisation of all drugs, including cannabis

Portugal decriminalised all drug use, including cannabis, in 2001. In the time since, rates of drug use have not changed significantly but the health and social outcomes for people who use drugs have improved – mostly due to changes in injecting drug use. It is still illegal to possess, supply or sell cannabis but the penalties are smaller.

Canada: A controlled, commercial model

Canada legalised recreational use of cannabis in 2018. Because this change was so recent, the impacts of regulation on social and health outcomes are not yet clear. Many people still purchase cannabis from illegal sources due to cost and supply issues because the commercial market is in its infancy, but the number of people reporting purchase for legal sources continues to increase.

The Netherlands: Illegal supply for ‘legal’ consumption

Purchasing cannabis from licensed ‘coffeeshops’ and possessing small amounts of cannabis is tolerated in the Netherlands due to steps taken in the 1970s. Over that time, the rates of cannabis use have been the same for people in the Netherlands compared to their European neighbours where cannabis is illegal. In contrast, arrests and convictions for possession for personal use are very low and arrests and criminal records for use or minor possession are extremely rare.

Australia: Legalisation, decriminalisation and depenalisation

Australia’s states and territories have taken different approaches to cannabis law reform. Cannabis remains prohibited under federal law, but in January 2020 the Australian Capital Territory (ACT) became the first to legalise recreational cannabis use (but not sales). South Australia and the Northern Territory have all decriminalised cannabis for possession of small quantities.

Further reading

Key resources and reports for more information about cannabis and drug law reform.

Overseas cannabis law reform

Cannabis Stats Hub, Statistics Canada (ongoing). A website that houses statistics related to health, justice, the economy and prices of cannabis for Canada following legalisation of cannabis in 2018, reported quarterly.

How will cannabis legalisation affect health, safety, and social equity outcomes? It largely depends on the 14Ps, Beau Kilmer (2019). An essay by a drug policy expert about 14 factors that should be considered during design of cannabis regulation to improve impacts of legalisation.

What Have Been the Public Health Impacts of Cannabis Legalisation in the USA? A Review of Evidence on Adverse and Beneficial Effects. Leung et al (2019). A summary of the empirical research on the adverse and beneficial public health impacts of cannabis legalisation in states in the US.

Uruguay’s Middle-Ground Approach to Cannabis Legalisation, Cerda et al (2018). An overview of the cannabis law reform in Uruguay, including a summary of the success and hurdles during implementation from 2013-2017.

Non-medical cannabis in North America: an overview of regulatory approaches, Lancione et al (2020). A summary of the regulations for legalised cannabis among the 11 US States, DC and Canada.

A Framework for the Legalisation and Regulation of Cannabis is Canada, Task Force on Cannabis (2016). The final report from the task force assembled in Canada to inform the government through recommendations to minimise harm through regulation.

Assessing the public health effects of the legalisation of recreational cannabis use, Forum in World Psychiatry (Volume 19, Number 2, June 2020). A series of articles and commentaries by leading experts relating to the health impacts of legalising cannabis.

Monitoring and evaluating changes in cannabis policies: insights from the Americas, European Monitoring Centre for Drugs and Addiction (2020). A technical report that reviews the new cannabis regimes in the Americas and their consequences.

Drug policy reform

NZ’s cannabis referendum 2020: Some facts and recommendations about the process of cannabis legalisation, New Zealand Institute of Economic Research (2020). A discussion paper about the possible economic effects of legalising cannabis in Aotearoa New Zealand, in which the authors estimate that taxing cannabis could raise $490 million in revenue a year.

International Guidelines on Human Rights and Drug Policy, United Nations Development Programme (2019). Guidelines developed by a coalition of UN Member States, WHO, UNAIDS, UNDP and leading human rights and drug policy experts to practically integrate international human rights commitments into national, regional and global drug policies and programmes.

Taking control of cannabis: A model for responsible regulation, NZ Drug Foundation (2019). An accessible overview of the government’s proposed regulation and suggestions of further inclusions in the legislation that could help to reduce cannabis-related harm in Aotearoa New Zealand.

Considering Marijuana Legalization: Insights for Vermont and Other Jurisdictions, RAND (2015). A detailed report that highlights the various policy options available for a regulated framework for cannabis

What can we learn from the Portuguese decriminalization of illicit drugs? Hughes et al (2010). An evidence-based analysis of the criminal justice and health impacts of drug reform in Portugal compared to neighbouring Spain and Italy.

A Comparison of the Cost-effectiveness of Prohibition and Regulation of Drugs, Transform Drug Policy Foundation (2009). An accessible document that provides a clear assessment of the regulatory issues related to cannabis law reform.

Advancing Drug Policy Reform: A New Approach to Decriminalisation, Global Commission on Drug Policy (2016). A report on decriminalisation that provides a clear assessment of current drug policy regimes and on the health costs.

A Quiet Revolution: Drug Decriminalisation Across the Globe, Release (2016). An an assessment of decriminalisation, rather than legalisation, that includes details about the key harms of criminalisation.

Social harm from cannabis prohibition

Drug law reform: balancing justice’s racist scales, Matters of Substance (November 2019). A series of articles by various authors in the Drug Foundation’s November publication that focus on the inequities in social harm that result from the current prohibitive cannabis laws.

The case for YES in the cannabis referendum, The Helen Clark Foundation (2019). A report highlighting evidence to support harm reduction through regulation of cannabis for recreational use, focusing on social harms.

Count the Costs, Transform Drug Policy (2015). A series of reports detailing the impacts of the prohibition of drugs. Of particular relevance are the ‘Harming, not protecting, young people’ and ‘Creating crime, enriching criminals’ reports.

Health impacts of cannabis

The Consequences of Cannabis Use, University of Otago (2020). A website that summarises the key findings related to cannabis from two of the world’s leading longitudinal studies that are run out of the University of Otago. Both studies followed around 1000 people born in the 1970s, one group in Dunedin and one in Christchurch. The website outlines findings related to health and social outcomes from cannabis use.

Cannabis: How it affects our health, Royal Society Te Apārangi (2020). A report summarising the evidence for how medicinal and recreational use of cannabis impacts health and highlighting knowledge gaps.

The health and social effects of nonmedical cannabis use, World Health Organization (2016). Building on contributions from a broad range of experts and researchers from around the world, this report summarises the current knowledge on the health impacts of nonmedical cannabis use.

Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations, Fischer et al (2017). A review of evidence on behavioural factors that contribute to adverse health outcomes from cannabis that users can change.

Public health implications of legalising the production and sale of cannabis for medical and recreational use. Hall et al (2019). An academic article assessing the current and possible future public health impacts of cannabis legalisation.

The Health Effects of Cannabis and Cannabinoids, National Academies of Sciences, Engineering, and Medicine (2017). A comprehensive review of scientific evidence related to the health effects and potential therapeutic benefits of cannabis, including the current knowledge gaps and research needs.

Cannabis press gallery

View our curated list of cannabis news in Aotearoa New Zealand, updated fortnightly.

Updates from the Office

Read reflections from co-chairs Juliet and Tracey as the cannabis project progresses.

Our panel

We gratefully acknowledge the contribution of our expert panel to this work. Read the panel’s terms of reference

Panel members and OPMCSA staff at the first panel meeting in September 2019. From left to right: Juliet Gerrard, Joseph Boden, Tracey McIntosh, David Newcombe, Hinemoa Elder, Chris Wilkins, Khylee Quince, Benedikt Fischer, Doug Sellman, Michelle Glass, Tamasailau Suaalii.

University of Otago

Professor Joseph Boden is a member of the Department of Psychological Medicine at the University of Otago, Christchurch. Originally earning a PhD in experimental social psychology, Joe held university lectureships in the UK and Australia before coming to New Zealand in 2002. Since 2005 he has been employed as a researcher on the long-running Christchurch Health and Development Study (CHDS), a longitudinal study of over 1000 New Zealanders born in Christchurch in mid-1977. In 2015 Joe was appointed Deputy Director of the CHDS and in 2019 he was appointed Director of the CHDS. His research interests include the psychosocial causes and consequences of substance use, abuse, and dependence; mental health and substance use epidemiology; and the social and psychological determinants of maladaptive behaviour including aggression and violence, among other topics.

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University of Auckland

Benedikt Fischer is the inaugural Hugh Green Foundation Chair in Addiction Research and Professor in the Schools of Population Health & Pharmacy at the University of Auckland. He holds additional academic appointments with the Department of Psychiatry, University of Toronto, Canada; the Centre for Applied Research in Mental Health & Addiction (CARMHA), Simon Fraser University, Vancouver, Canada; and the Department of Psychiatry, Federal University of Sao Paulo (UNIFESP), Brazil. Prior to moving to New Zealand in 2018, Benedikt held senior academic appointments in Canada, as senior scientist at the Centre for Addiction & Mental Health and the Addiction Psychiatry Chair at the University of Toronto (until 2018) and as the CIHR/PHAC Applied Public Health Research Chair and Director of CARMHA at Simon Fraser University, Vancouver (2008–2014).

Benedikt’s scientific work focuses on the social, behavioural and health outcomes of, and evidence-based prevention and treatment interventions for psychoactive substance use and related co-morbidities (e.g. mental health, pain, infectious disease) in an interdisciplinary, public health-oriented framework. His scientific work is strongly geared towards knowledge translation for improved interventions, systems and policy. For more than two decades, he has made major scientific contributions to public health-oriented cannabis control and interventions, including as lead-author of the internationally adopted ‘Lower-Risk Cannabis Use Guidelines (LRCUG)’.

Benedikt acted as Senior Science Advisor to the Canadian government for the development of its cannabis legalisation framework, and has advised other governments (e.g. Uruguay) on cannabis and health policy issues. He is a co-author of several international books: ‘Drug Policy & the Public Good’ (Babor et al., 2018) and ‘Cannabis Policy: Moving Beyond Stalemate’ (Room et al., 2010). He has served in science advisory roles for preeminent institutions (e.g., CIHR’s Institute of Neuroscience, Mental Health and Addiction; the Mental Health Commission of Canada, Health Canada). Benedikt is a frequent and sought-after expert speaker and commentator to academic, media and general public audiences on his topics of expertise.

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University of Auckland

Tracey McIntosh is of Ngāi Tūhoe descent and is Professor of Indigenous Studies and co-head of Te Wānanga o Waipapa (School of Māori Studies and Pacific Studies) at the University of Auckland. She was the former co-director of Ngā Pae o te Māramatanga – New Zealand’s Māori Centre of Research Excellence. She previously taught in the sociology and criminology programme at the University of Auckland. She was a Fulbright Visiting Lecturer in New Zealand Studies at Georgetown University in Washington D.C. and lectured at the University of the South Pacific in Fiji. She has sat on a number of assessment panels including PBRF panels (Māori Knowledge and Development and Social Sciences), the Marsden Social Science panel, Rutherford Discovery, James Cook Fellowship and Health Research Council panels. In 2012 she served as the co-chair of the Children’s Commissioner’s Expert Advisory Group on Solutions to Child Poverty.​ In 2018–2019 she was a member of the Welfare Expert Advisory Group and Te Uepū Hapai i te Ora- The Safe and Effective Justice Advisory Group. She sits on a range of advisory groups and boards for government and community organisations. She currently delivers education and creative writing programmes in prisons.​

Her recent research focused on incarceration (particularly of Māori and Indigenous peoples), gang whānau issues and issues pertaining to poverty, inequality and social justice.

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AUT

Khylee Quince is from the iwi of Te Roroa/Ngapuhi and Ngati Porou. She teaches criminal law, advanced criminal law and youth justice. Her research interests lie within those fields – in particular, Māori and the criminal justice system, tikanga Māori and the law, restorative justice and alternative dispute resolution, Māori women and the law, and indigenous peoples and the law.

Prior to joining the University of Auckland’s Law Faculty in 1998, Khylee practiced in criminal and family law for three years. Khylee is now Associate Head of School and Director of Maori and Pacific Advancement at the AUT School of Law. She is also a trustee on the New Zealand Drug Foundation.

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University of Auckland

Tamasailau Suaalii-Sauni currently teaches in the criminology programme. She completed both undergraduate and postgraduate university studies at the University of Auckland. She held teaching fellow, research fellow, lecturing and deputy director positions within the University of Auckland’s Department of Sociology, Department of Maori and Pacific Health, and Centre for Pacific Studies 1998–2008. She moved to the University of Otago to take up a senior research fellow position with the Centre for International Health based at the National University of Samoa in Apia Nov 2008–July 2011. After this, she took up senior lecturer and programme director positions with Victoria University of Wellington’s (VUW) Va’aomanu Pasifika Unit from 2011–2016. Tamasailau returned to the University of Auckland in October 2016 as Associate Professor in Sociology/Criminology at the School of Social Sciences. As well as working for the university sector, Tamasailau has also held honorary and part-time senior researcher and programme evaluator roles in the state and private sector – mainly with the Waitemata District Health Board’s Clinical Research and Resource Centre (2003–2008), and with (as co-director) Pacific Research and Development Services Ltd (1998-2003). Tamasailau was a member of the Superu and VUW central ethics committees.

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University of Auckland

Ko Pārengarenga te moana
Ko Tawhitirahi te maunga
Ko Awapoka te awa
Ko Te Aupouri, ko Ngāti Kurī, ko Te Rarawa, ko Ngāpuhi nui tonu oku iwi
Ko Hinemoa taku ingoa

Hinemoa Elder is a Fellow of the Royal Australia and New Zealand College of Psychiatrists and has been a consultant child and adolescent psychiatrist since 2006. Hinemoa is the Māori Strategic Leader for the Centre of Research Excellence (CoRE) for the Ageing Brain. In addition to her initial medical qualifications, Hinemoa has a PhD (Massey University, 2012) and is former HRC Eru Pomare Post-Doctoral Fellow (2014–18) in which she developed a novel recovery approach grounded in Te Ao Māori (Māori world view), for Māori with traumatic brain injury, their whānau (extended families) and professionals which is now being used in community rehabilitation services. She continues to work clinically as a neuropsychiatrist and youth forensic psychiatrist. She is an expert in the areas of psychological trauma and cultural psychiatry. She also currently works at the Child and Family Unit, Starship Hospital.

Hinemoa has served on several Ministry of Health reference groups. She is a deputy psychiatrist member of the NZ Mental Health Review Tribunal and a Specialist Assessor under the Intellectual Disability (Compulsory Care and Rehabilitation) Act 2003. She is a member of the International Science Advisory Board to the National Science Challenge ‘E tipu e rea, a better start’.

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University of Otago

Michelle Glass took up the position of Head of the Department of Pharmacology and Toxicology and the University of Otago in July 2018. This appointment came after 17 years at the University of Auckland, including six years as the Head of Pharmacology and Clinical Pharmacology. As a molecular pharmacologist, Michelle’s research focuses on the expression, function and molecular pharmacology of the cannabinoid receptors and their potential role in treatment of neurodegenerative diseases.

Following her PhD, in which she mapped the then newly discovered cannabinoid CB1 receptor in the human brain, she worked on cannabinoid receptor signalling as a postdoctoral fellow at the National Institutes of Health in Bethesda, Maryland for five years before returning to New Zealand in 2000 to take up a role as a lecturer (and researcher) within the Department of Pharmacology at the University of Auckland. She has published over 90 papers on cannabinoids, and numerous book chapters.

Her contributions to the field have been acknowledged by an early career award from the International Cannabinoid Research Society in 2009 and by election to President of this society in 2015.

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University of Auckland

Associate Professor David Newcombe is Academic Director of postgraduate addiction programmes and Head of the Section of Social and Community Health in the School of Population Health, and Associate Director of the Centre for Addiction Research. He has been working in the addiction sector for more than 20 years in various clinical and research roles both in Australia and New Zealand. Prior to moving to New Zealand, David was Senior Project Manager at the World Health Organization (WHO) Collaborating Centre for Research in the Treatment of Drug and Alcohol Problems at the University of Adelaide. Here, he managed an international multisite evaluation of opioid pharmacotherapies for the treatment of opioid dependence and the Australian site of the validation of the WHO Alcohol, Smoking and Substance Involvement Screening Test (ASSIST) study.

His current research interests include: screening for problematic substance use and assessing the efficacy of brief interventions in different at risk groups; the clinical pharmacology and psychopharmacology of drugs of abuse; and clinical effectiveness of pharmacotherapies used to treat alcohol and drug problems.

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University of Otago

Doug Sellman is a psychiatrist and addiction medicine specialist. He is recognised as a national leader in the addiction field in New Zealand having been Director of the National Addiction Centre (NAC), University of Otago Christchurch from 1996–2017. He has also contributed to the development of a highly successful national postgraduate training programme in the area of addiction and co-existing disorders. He has been involved in a broad range of addiction-related research projects with over 100 peer-reviewed publications involving alcohol, cannabis, opioids, nicotine, methamphetamine, gambling and food, primarily from a treatment perspective.

Over the past 15 years this work has turned increasingly towards public health and prevention. He was promoted to a Personal Chair within the University of Otago in 2006, and in 2009 was one of the initiators of Alcohol Action NZ, a medically-led advocacy group for alcohol law reform. His clinical work was in adult addiction services from 1987–1994 and then in youth services from 1994–2014. He is now partially retired and runs a small private practice with a special focus on food addiction and obesity, while continuing research and teaching work at the NAC.

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Massey University

Chris Wilkins is the leader of the drug research team at SHORE & Whariki Research Centre, College of Health, Massey University. Chris has research expertise in drug trends, drug markets, public health, and drug policy. Over the past 20 years he has completed a range of studies of drug use in New Zealand with particular focus on methamphetamine, cannabis, legal highs, ecstasy and the non-medical use of pharmaceuticals. Chris Wilkins has published numerous journal articles on drug use, contributed to three books and regularly reviews manuscripts for Addiction, the International Journal of Drug Policy, Drug & Alcohol Review and Drug and Alcohol Dependence. Chris Wilkins has been an invited speaker at international meetings convened by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), and at the United States National Institute for Drug Abuse Community Epidemiology Working Group (CEWG). He regularly presents papers at the annual meetings of the International Society for the Study of Drug Policy (ISSDP).

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Acknowledgements

We gratefully acknowledge Dr Beau Kilmer, Dr Matire Harwood, Dame Susan Bagshaw, Tangi Noomotu and Professor Wayne Hall for their expert review of this content. We also thank Dr Michelle Sullivan for her contribution to this project.

 

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Further input

Details of meetings with external stakeholders are available here.

Authorised by Juliet Gerrard, 1-11 Short St, Auckland CBD, Auckland 1010