The difficulty is that if we use the test of risk as the benchmark for what should be prohibited, then tobacco, alcohol and gambling should also be banned. Tobacco, with an addiction rate of 32 per cent, kills around 5000 New Zealanders every year. Alcohol, with an addiction rate of 15 per cent, kills about 700. It is also connected to around 25 per cent of all injuries in medical emergencies; and half of all serious violent crime.
Some 2.5 per cent of all New Zealand adults experience significant gambling-related harm, and a further 5 per cent are low risk but still experience some harm. The yearly economic costs are about $4.9 billion for alcohol, $1.7 billion for tobacco, and at least $2 billion for gambling.
The risks of alcohol, tobacco and gambling are not prohibited for two reasons.
First, law must be reconciled with reality. We could not build enough jails to hold all of those who wish to smoke, drink or gamble if these activities were made illegal. The same logic needs to be applied to cannabis, where despite five decades of trying to stop the problem, at least 400,000 users each year use the substance.
Almost half of all New Zealand adults have tried it at some point in their lives.
Despite this, police are still required to devote 580,000 hours and $100 million a year fighting the tide.
The result of these efforts is not a dent in demand, but some 10,000 convictions for cannabis-related offences in the past six years.
Second, whether in historical settings or contemporary societies in which freedom and liberty are subscribed to, attempts to stop alcohol, tobacco or gambling always fail. In the process of failure, the power of addiction or desire will lead users to source what they need through illegal markets.
Those who supply the illegal market will get rich, and create all of the negative impacts that always accompany crime and fall on the wider community.
The profits to be made are spectacular. In the United States, the profit from the sale of legal recreational and medical marijuana sales is currently US$2.9 billion ($4.3 billion). It is estimated to be US$22 billion by 2020. When this becomes regulated, business is taken away from criminals and given to law-abiding people who pay tax. The economic potential to New Zealand of both domestic and international markets could be remarkable.
Moreover, in a regulated market producers obey rules on what is produced to what level, where it is produced and sold, when and to whom. Producers obey these rules because they want to protect their profit streams. And from the profit comes tax, which can then be spent on educating the public about the associated risks of this drug, paying for its regulation, and dealing with the addicts who will always be present whether the drug is legal or illegal.
Accordingly, the question of the referendum should not be between two types of flag, but as was asked to the four million citizens of Oregon: Do we wish to "allow possession, manufacture, sale of marijuana by/to adults, subject to state licensing, regulation and taxation?" Yes or no?
• Alexander Gillespie is professor of law at the University of Waikato.
Debate on this article is now closed.