The prospect of legal weed has divided Kiwis for years - but, on October 17, we'll head to the polls to decide whether we're in favour of making recreational cannabis lawful.
It's a debate that's raged on since well before the 2017 election, when the Greens successfully negotiated for it to be put to a public referendum as a condition of forming a government with Labour.
Many Kiwis argue cannabis is dangerous - particularly for young people - and that legalising it would only make it more accessible and prevalent, creating more harm.
But others say its health and social impacts are limited, and that legalisation would generate funds that could be used to address cannabis use as a health issue.
To help you make a decision on which way to vote, we've explored what the data says about the harms caused by weed, and taken a look at how that stacks up with the dangers of alcohol, tobacco and other illicit drugs.
We also investigate what benefits could come from its legalisation, and whether these could offset the harms caused by cannabis use.
How harmful is cannabis really?
Data shows the harm caused by cannabis use in New Zealand is significant. The 2016 New Zealand Drug Harm Index (DHI) estimated the social cost of cannabinoid use to the country at $1.283 billion.
Recreational cannabis is associated with a range of negative outcomes, a 2019 Royal Society Te Apārangi report found - including mental illness, drug use disorders, respiratory illness, impaired cognition, increased road accidents, and lower birth weight in babies.
A pair of longitudinal studies carried out over 40 years in Christchurch and Dunedin concluded much the same, and also noted links to psychosis, gum disease and impaired lung function.
But Ross Bell, chief executive of the pro-legal cannabis NZ Drug Foundation, says these harms are "low to moderate" and most prevalent among young people and chronic users.
"This is not to say it doesn't have its problems... we do know harm does exist, but we also know from really good New Zealand research where that harm really lies."
The impacts of weed also vary greatly based on the method of consumption, and the quantity of chemical compounds cannabidiol (CBD) and tetrahydrocannabinol (THC).
And unlike many of its fellow prohibited drugs - and even some legal ones, like alcohol and tobacco - cannabis is very rarely deadly.
The DHI estimates it's responsible for 32 deaths a year - though it should be noted none of these are by way of cannabis overdose, which is widely understood to be impossible.
How weed compares to 'killer' tobacco, 'driver of chaos' alcohol
The $1.283 billion cannabis harm costs New Zealand is undeniably large, but it pales in comparison to that caused by our legal vices, alcohol and tobacco.
Alcohol harm advocacy group Action Point estimates alcohol's social costs - in the form of lost productivity, unemployment, justice, health, ACC and welfare - come to an astronomical $7.5 billion per annum. This is seven times what the excise tax on alcohol was worth to New Zealand last year.
There is little recent research on the societal cost of tobacco, but a 2010 Ministry of Health study estimated the health costs of smoking came to $1.9 billion. Meanwhile excise from tobacco is expected to generate more than $2 billion for New Zealand.
Bell says both tobacco and alcohol come with a greater number of negative health impacts, many of which are more serious than those caused by cannabis.
"They've been around and legal for a long time - we've had pretty loose controls over those substances," he told Newshub.
"You can buy it from the supermarket; you can buy it pretty cheap. With tobacco, it used to be that you could smoke on aeroplanes. For both substances, it was in-your-face and pretty much part of the culture."
Bell describes tobacco as a killer, and says it's one of just a few products that is "almost designed to harm".
"It's made up of compounds and chemicals that are really, really dangerous. You've got the addictive part, nicotine, which makes people keep using it. But then you've got the other stuff in there that kills people, that creates lung cancer and other health issues."
The Ministry of Health says there are as many as 60 chemicals in cigarettes that can cause cancer. It estimates 5000 lives are lost each year from smoking - 13 a day - and that half of all long-term smokers will die from diseases caused by cigarettes.
Alcohol use is also associated with myriad negative health and social effects in New Zealand. It's linked to a third of all arrests, half of all serious violent crimes, and causes between 600 and 1000 deaths each year.
Director of Otago University's National Addictions Centre Doug Sellman published research earlier this year that directly compared the effects of ethanol in alcohol against that of THC, the main psychoactive substance in cannabis.
He found that of 13 commonly discussed issues related to drugs and health, alcohol is more harmful than cannabis in all but four. On only one count - anxiety during intoxication - was cannabis deemed worse than alcohol.
On seven points, alcohol was found to be significantly more harmful - death from overdose, aggression during intoxication, death from severe withdrawal, links to major depression, links to cancer, fetal brain damage, and liver and other organ damage.
"The differential harm profile demonstrates how irrational our drug laws are," Prof Sellman wrote in a piece for the New Zealand Herald in July.
"If the choice was to have just one legal drug, it would make more sense for cannabis to be legal and alcohol to be illegal based on health harms."
How does cannabis stack up against other drugs?
The $1.283 billion of harm caused by cannabis dwarfs the social costs of other illicit drug types, such as amphetamine stimulants ($364 million), hallucinogens and psychedelics ($22.3 million), and opioids and sedatives ($175.9 million).
However these costs are skewed significantly by the prevalence of cannabis compared to these other drugs. The DHI shows the 274,400 people who smoked weed in 2016 accounted for well over two-thirds of New Zealand's total drug users.
The 2018/19 NZ Health Survey found 15 percent of adults had used cannabis in the past year, with 8.5 percent (330,000 adults) using it monthly. Use is particularly high among Māori, young people and those in poorer areas.
When other metrics are applied to the data, cannabinoids actually prove to be less harmful than almost all other illicit drug types.
Take the social cost per drug user, for instance; the DHI estimates this comes to $29,100 a year for someone dependent on cannabis. This is well below what dependent amphetamine-type stimulant ($116,600) and opioid and sedative ($44,300) users cost the country.
This difference is just as marked among casual drug users.
The data is skewed further because the 'cannabinoids' sub-group is composed not just of cannabis, but its synthetic counterpart as well. In the DHI, a dozen experts ranked synthetic cannabis as far more harmful than the natural version.
Even still, cannabinoids are by far the least harmful of all illicit drug types per kilogram. Amphetamines come with more than 26 times the social cost by this metric.
The DHI also indicated casual cannabis users were at 'very low to low risk', while those dependent on weed were at 'low to medium risk'. These evaluations saw cannabis rank third-least harmful of all illicit drugs, only bettered by LSD and ecstasy.
What could cannabis legalisation do for New Zealand?
A pair of Business and Economic Research Limited (BERL) reports obtained by Newshub earlier this month show the Government could make nearly $1.1 billion in annual taxes if cannabis is legalised.
This covers the vast majority of the estimated $1.283 billion in social harm cannabinoids are estimated to cause each year.
It's not just tax revenue, either; there are a raft of financial benefits to legalising weed.
The BERL reports estimated the cannabis industry could employ about 5000 people should Kiwis vote to make one legal - a boon for the new Government as they wrestle with the expected surge in unemployment brought on by COVID-19.
Legalisation would also take weed out of the hands of gangs and criminals, handing power to legal suppliers operating in a regulated market.
Meanwhile most expenditure on courts, prisons, police, customs and other enforcement measures for cannabinoids - which comes to a combined $198.3 million per annum - could be dropped.
These funds could then be used to bolster cannabis-related education, treatment, counselling, hospital admissions and ambulance attendances - health interventions we only shell out $68.2 million on at the moment.
Of course, these benefits will be almost worthless if legalising cannabis results in a major increase in use, exacerbating the health problems New Zealand's already grappling with.
But Bell says jurisdictions overseas have proven the "explosion of use" a lot of Kiwis are worried about if cannabis was to be legalised simply doesn't happen - especially not among those most vulnerable to weed's negative effects.
"Washington state and Canada, for example - the real issue for us is 'will cannabis use among young people increase?' That's the thing we should be worried about," he said.
"And actually, what we've seen in those places is that youth use has not increased. In some cases it's stayed the same, but in most cases it's actually gone down - which is absolutely counter-intuitive.
"We have seen already in places that've legalised that there may be a slight increase in use among adults - funnily enough, the biggest increases we've seen in places like Colorado and Canada are among people aged over 50."
Researchers don't agree on what causes this uptick in cannabis use. Bell says some believe it's down to increased accessibility, while others argue legalisation allows people to be more honest about their use, which is then reflected in the data.
But Bell says even if use does increase, the removal of criminality, fear and stigma around cannabis means those people at greater risk of negative health impacts find it easier to get help.
"The fact you can then start putting money into drug prevention, education and treatment means it's easier to help that proportion of people who might get into trouble with cannabis use."
A cost-benefit analysis of the NZ Drug Foundation's drug reform plan carried out by economic consultancy Sense Partners in 2018 found cannabis legalisation could make New Zealand tens of millions of dollars better off.
"Criminal justice costs would fall by an estimated $6 million to $13 million per year, as fewer people go to court and prison for cannabis possession and supply offences," the report reads.
"The change in setting implies additional referrals to community or residential treatment services, covered as part of the proposed boost in drug education, harm reduction and treatment services.
"Based on these effects, New Zealand would be better off by $10 million to $53 million a year as a result of legalisation."
The report does note, however, that reinvestment of that money into drug harm reduction policies appears to be a crucial element of successful cannabis reform overseas.
"Data to date does not show any significant change in cannabis use by youth in Colorado, but an increase in Washington - reiterating the importance of education and prevention programmes."
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