James Farmer


Cannabis Legal Reform - Arguments For and Against

Thursday, August 13, 2020
I have consistently believed that cannabis is a harmful substance and that people who use it for “recreational purposes” would be more sensible to choose a healthy form of recreation that doesn’t put them and those dependent on them, i.e. their children and future children, at risk of harm.

A disappointing feature of the forthcoming cannabis reform referendum (apart from the fact that it's being held at all) is that it is the consequence of a political deal between the Labour and Green Parties.  Another feature of dubious morality is that it is being promoted as a measure that will generate tax revenues that can be used, as the proposed Cannabis Legislation and Control Bill says, “to reduce the harms associated with cannabis use experienced by individual, families, whanau, and communities in New Zealand”.   Assuming the Bill is successful in achieving its objectives of eliminating the (non-tax-paying) black market – as to which, see below – and that legal cannabis becomes more readily available, the happy equilibrium will be attained of greater access to cannabis, more people using it, more people affected by its harmful effects and more public money to address those effects.

With the referendum now only weeks away, it is a useful time to collect together the arguments for legalization and test their soundness.  The arguments, as they appear to be, are:

(1) Cannabis is no more harmful than alcohol and it is legal to consume alcohol and so it should be too for cannabis.

(2) Medicinal cannabis is now legal and cannabis for recreational use should be also.

(3) The legalisation of cannabis will decrease any harm to users because its production, supply, strength and price will be regulated.

(4) Legalisation of cannabis supply and use will eliminate the black market.

(5) It is wrong that people who use cannabis should be convicted under the criminal law.

My analysis, by reference to research, written expert and professional opinion, and plain logic suggests that there are flaws with each of these propositions.  My conclusion is that, properly used, the amendment that was made to the Misuse of Drugs Act 1975 last year that gives Police discretion not to prosecute where a health-centred or therapeutic approach can be achieved is more likely to achieve the proposed Bill’s objective of reducing harm from cannabis use than wholesale legalisation of the use of the drug.


In a recent article (3 August 2020) in The NZ Herald, Professor Mary Cannon, Professor of Psychiatric Epidemiology and Youth Mental Health at the Royal College of Surgeons in Ireland, described this proposition as spurious and along the lines of “Would you rather be eaten by a lion or a bear or run over by a truck or a bus?”  She went on to make the point that, while there is a rare condition known as alcohol hallucinosis which can cause hallucinations and paranoia in heavy life-time alcohol users suffering an alcohol withdrawal reaction, this is not a psychotic disorder.  By contrast, based on extensive medical research, cannabis “is strongly associated with psychotic symptons and psychotic disorders such schizophrenia”.  She continued: “In fact, cannabis use is now the most powerful single environmental risk factor for psychotic disorder.”  She has also referred (in a separate Irish Times article cited below) to a statement by Dr Brendan Kelly, Professor of Psychiatry at Trinity College Dublin, that: “It is now exceedingly rare to meet a man with new-onset schizophrenia or a related disorder who was not smoking cannabis before he experienced symptons”.

Again based on research, Professor Cannon says that it has been established that young people (teenagers and young adults) are particularly vulnerable because of the effect that cannabis has on the developing brain. Those who start using cannabis before the age of 15 were found to have 4 times the risk of being diagnosed with schizophrenia by the age of 26.  There was evidence also of an 8 point drop in IQ that appears to be irreversible and lesser employment achievement. Professor Cannon described the psychosis associated with cannabis as one with “high levels of agitation, aggression and paranoia and can present a risk to family and others”.

Parents who may be indulgent or prepared to condone the use of cannabis by their teenage children should watch the following easy-to-follow account of the effects on teenage brain development: https://www.youtube.com/watch?v=FvszaF4vcNY

Professor Cannon is far from being on her own.  A joint review of 18 separate research studies by Marconi, Di Forti, Lewis and Murray (Meta-analysis of the Association between the level of Cannabis Use and Risk of Psychosis, (2016) 42 Schizophrenia Bulletin 1262) established that higher levels of cannabis use were associated with increased risk of psychosis including schizophrenia: https://academic.oup.com/schizophreniabulletin/article/42/5/1262/2413827

In relation to alcohol, Professor Cannon in her Herald article makes the point that the failure of governments world-wide to control alcohol harm “shows that once an addictive substance is legalised and freely available, public health takes a second place to profit”. As she puts it: “Once society normalises the widespread use of a drug, it is almost impossible to undo that and put the genie back in the bottle”.


In a separate article from her Herald piece (published in The Irish Times, 16 September 2019), Professor Cannon refers to a book written by a former New York Times journalist, Alex Berenson, who pointed to campaigns that have been successful in obtaining acceptance legally of cannabis for “medicinal use” which are then used as a platform for persuading the public and legislators to authorise full legalisation for recreational use.  She pointed to doubts expressed by a group of 20 doctors who thought that the evidence that cannabinoids have medicinal benefits is “limited”, that they exist for a very small number of conditions and that the claims have been “grossly distorted”.  Others however claim differently and there is opinion in the United States that medicinal cannabis is a more acceptable pain killer than prescribed opioids that, misused, have led to addiction and death.

Whatever the facts as to the utility of cannabis for medicinal purposes, that is an issue that is “completely separate” (to use the New Zealand Ministry of Health’s own words when describing the Medicinal Cannabis Scheme) from recreational use. As the Ministry says, a prescription from a doctor must be obtained for medical use and there are strict rules around supply and strength: https://www.health.govt.nz/our-work/regulation-health-and-disability-system/medicinal-cannabis-agency/about-medicinal-cannabis-scheme.

Interestingly, and a lesson for those who do not give adequate consideration to the law of unintended consequences, is the experience in Canada described by Mike Power in his recent Guardian article referred to below.  This was that the traditional growers of medicinal cannabis (legal in Canada since 2001) diverted their product to the more lucrative recreational market when it became lawful in 2018, which made supply to medical users short and forced them to pay higher prices from suppliers of recreational cannabis.

In truth, according to the logic that legalising cannabis for recreational use is not really that different from the existing lawfulness of its use for medicinal purposes, there should be no objection to our legalising morphine for recreational purposes because it is used for medicinal purposes.  The "Opioid Crisis" in the United States demonstrates just how dangerous it is when the use of medicinal drugs is normalised: https://www.drugabuse.gov/drug-topics/opioids/opioid-overdose-crisis 


The Explanatory Note to the proposed Bill states that its “overarching objective” is to reduce harm associated with cannabis use.  The measures in the Bill that will achieve this objective (with my comments) are said to include:

(1) Raising public awareness of the risks associated with cannabis consumption – (one wonders why it is necessary to make a substance that is presently unlawful lawful in order to educate the public of its dangers.)

(2) Restricting young people’s access to cannabis – (the Explanatory Note answers this by saying: “The purchase, possession, and consumption of cannabis will remain illegal for people aged 19 years and under.”)

(3) Providing access for adults to cannabis that is legal and quality-controlled – (that assumes that access to cannabis that is unlawfully supplied and above regulated potency limits will not be available, as to which see below.)

(4) Deterring the illegal supply of cannabis by controlling its potency and regulating the whole supply chain – (not the experience of Canada and American States where legalisation and regulation have been introduced: see below.)

(5) Encouraging compliance with the legislation and ensuring that “responses to breaches are proportionate and incorporate a focus on reducing overall harm” – a worthy objective which is achievable now under the 2019 amendment to the Misuse of Drugs Act: see below.)

These propositions are able to be assessed by reference to the experiences that are resulting from other jurisdictions (notably in North America) where cannabis supply and use has been legalised in one form or another.

On the question of whether the legalisation that has occurred has led to a reduction in harm from cannabis use, reference should be made to a recently published article by Drs Robin Murray and Wayne Hall (Will Legalisation and Commercialisation of Cannabis Use Increase the Incidence and Prevalence of Psychosis: American Medical Association, JAMA Psychiatry, 8 April 2020).  They find that, while the risk of dependence among cannabis users was estimated at 9% over 20 years ago, that number was now closer to 30% in those States in the United States that have legalised its use, with attendant increases in such harmful effects as cognitive impairment and effects on the unborn child by women who use it to combat nausea.  They refer to increased risks of depression and suicide but conclude that “by far the strongest evidence concerns psychosis [including] an increased risk of later schizophrenia-like psychosis”:

An appalling feature about the claim that legalisation will reduce harm from cannabis use is that the harm is grossly underplayed by the cannabis reform lobby.  Patrick Cockburn, writing in The Independent on 22 June 2018, says: “A depressing aspect of the present debate about cannabis is that so many proponents of legalization or decriminalization have clearly not taken on board that the causal link between cannabis and psychosis has been scientifically proven over the past ten years, just as the connection between cancer and cigarettes was proved in the late 1940s and 1950s.”  And, as he also points out, since the time that the message did get through to the public about the link between tobacco and cancer, the number of cigarette smokers in Britain has fallen by two-thirds. Public education does not require legislative reform: it can be pursued now.

Another basis for the claim that a lawful regulated market will reduce harm is that the potency of the product will be limited by regulation. That assumes that the Black Market will disappear and that only cannabis with a controlled and limited potency will be available.  That leads to the next proposition considered here.


The short answer to this proposition, based on North American experience, is no. The longer answer, however, is that there are two effects of legalisation, both of which make the present effects of the Black Market considerably worse.

The first is described by Patrick Cockburn.  In the same article referred to above, he makes the point that “the legalization of cannabis legitimizes it and [sends] a message that the government views it as relatively harmless”.  He then makes the obvious point that those who are licensed to manufacture and supply a product to the market will be motivated to increase the number of their customers and hence to increase their profits.  Increased use will of itself lead to increased harm. 

It is reasonable to predict also that lawfulness is likely to remove the barrier to cannabis use that exposure of unlawful use and possible conviction, and its effects on travel, employment and reputation, has as a deterrent to many adults. It has been suggested that the very fact of unlawfulness is an incentive to teenagers to be “cool” by partaking in an illegal activity.  If so, nothing changes because supply to and use of cannabis by teenagers remains unlawful in an otherwise legalised regime.

The second consequence from legalisation is that, faced with competition in the form of licensed operators, the illegal market will not quietly retire but will develop innovative ways of competing with the regulated product.  That is very much the North American experience to date.

A journalist, Mike Power, who had followed the implementation of Canada’s Cannabis Act of 2018 legalising cannabis use, reported recently that the black market in Canada was “still vibrant”: Stoners cheered when Canada legalised cannabis.  How did it go so wrong?, The Guardian, 5 April 2020.  More than that, stocks in firms (described as “vulture capitalists”) that were licensed to grow and supply cannabis at the end of 2019 crashed with substantial staff redundancies. This was true also in the United States with share prices dropping by up to 80%.

The Black Market, it seemed, was very much up to the competitive challenge that the new regulated producers presented.  Power’s account was as follows:

“… the price [of legal cannabis] was almost double that of the illegal market…  That was caused by tax burdens and overheads: the legal market has to comply with regulations on fungicide and pesticide residue levels, and draconian security requirements for grow sites, such as huge vaults in which to store the cannabis and record-keeping for every person who enters these vaults.  The illegal market, meanwhile, is completely unregulated – and thriving because of this. Statistics Canada, a state agency, reports that just 29% of cannabis users buy all of their product from a legal source.”

Another problem identified in Power’s article was that the new, regulated, commercial growers, it seems, lacked the experience to produce good quality product as a result of faulty growth and harvesting techniques.  A further problem was the delays in establishing lawful retail outlets which left the new growers with a glut of the product (assessed by Government inventory figures as being “a stockpile of grass weighing in at 400 tonnes”).  This leads him to say that drug laws “generate countless unintended consequences – in fact, drugs laws often create the exact opposite outcomes to those desired … ironically, and with a beautifully stoned logic, it turns out that legalizing cannabis in Canada has generated just as many challenges as it solved”.


Following on the theme just discussed, there is justified concern that, if the regulated cannabis market does indeed dint the Black Market’s present dominance in cannabis supply this may serve to encourage further the efforts of the Black Market to compensate for lost revenues by stimulating demand for methamphetamine and marketing it as a cheaper and more potent drug. That may be true also of heroin and cocaine, though these drugs are less prevalent in New Zealand because they face import difficulties. 

There can be no sensible opposition to the proposition that methamphetamine and heroin are highly addictive and known to lead to paranoia and violent and criminal behaviour by users: https://search.informit.com.au/documentSummary;dn=350578761436198;res=IELHSS; https://www.researchgate.net/publication/234065228_Aggressive_behaviour_and_heroin_addiction There are also the economic costs to society, for example to name just two, from the costs of treating people who develop psychosis of one form or another, and from the need to decontaminate and even destroy houses rented to tenants (including State-owned houses) who use them to manufacture methamphetamine.  There are also the social and personal costs from the effects of drug addiction – for example those suffered by young women led into prostitution to fund that addiction.  The high number of deaths that result in countries where heroin is freely available is a real cost to Society: for example, 953 deaths in a 5 year period in New South Wales:


One does not hear a case being made for the legalisation of the manufacture, supply and use of heroin and methamphetamine (or cocaine and other hallucinatory so-called “hard” drugs), not even by libertarians who argue that the individual should have a free choice as to what he or she puts into his or her body.  It is not seriously challenged that the criminal law in particular does have a legitimate role to play for these drugs, certainly in relation to manufacture and supply.

The case for decriminalisation of drugs, in relation to the hard drugs and for cannabis, is more complex.  There is no dispute that it is legitimate for Society to be concerned about adverse health effects of the kind identified in relation to cannabis – various forms and levels of psychosis in particular.  The proposed Cannabis Bill says as much.  The claim however that legalisation will reduce harm and “improve access to health and other relevant support services” is more dubious.  Portugal is often cited as a country that has successfully decriminalised the use of marijuana - which it has.  However, the use of cannabis still has legal consequences.  Persons apprehended with even small amounts of drugs (including cannabis) can be ordered to appear before a “dissuasion panel or commission” consisting of legal, social and psychological professionals and repeat offenders may be ordered to undergo treatment: https://www.mic.com/articles/110344/14-years-after-portugal-decriminalized-all-drugs-here-s-what-s-happening#.ZqBzt6DlT

A health-focused solution, but via the deterrence and incentivisation (to seek assistance) of the criminal law, is in fact available now in New Zealand, a fact that scarcely rates a mention in the current public debate leading up to the referendum.  In August of last year the Misuse of Drugs Amendment Act was passed, inserting section 7(5) and (6) into the principal (1975) Act.  This directs the Police not to prosecute drug users (of all kinds) where prosecution is not in the public interest.  In determining that question, regard must be given to whether a health-centred or therapeutic approach would be more beneficial to the public interest in the particular case than criminal punishment.  Interestingly, the proposed Cannabis Bill adopts a similar concept in the case of persons under the age of 20 years who will be prohibited from growing, possessing or using cannabis.  A youth who breaches that provision will be issued with an infringement notice and ordered to pay an infringement fee of $100 or a fine of up to $200 (presumably for repeat offenders).  However, the infringement notice may include a requirement to attend a support service and if that is done within the prescribed period the fee is waived and the notice is revoked.

That provision surely provides a surer incentive to a health-centred outcome for those who are using and in danger of harm from cannabis use.  The Police are already taking a hard line on the enforcement of existing laws against the manufacture, growth and supply of harmful drugs (including cannabis).  If they need more resources to be more effective, they should be given them.  The exercise of their discretionary powers under the 2019 Amendment should be encouraged and their effectiveness monitored.  That is a sounder and safer way forward than the radical proposal of the draft Cannabis Legislation and Control Bill (if enacted), with its risks and undesirable consequences that overseas experience reveals.

James Farmer QC

13 August 2020

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