It won't matter whether the next government is Labour or National-led, because the public referendum on October 17 is binding. In the event of a "yes" vote, the End of Life Choice Act would come into force in October 2021.
Public support for voluntary euthanasia has been consistently strong for the past 20 years, with most polls between 60 and 70 per cent in favour. But legalisation would still be a radical act in international terms.
Just five countries have legalised voluntary euthanasia or assisted dying worldwide, along with several states in the United States and Australia.
There is no clear political, socio-economic or generational divide in New Zealand on assisted dying. Nearly three years of debate on the End of Life Choice Act have shown that whereas some people are guided by their faith or their profession, most people base their position on life experience: either watching a loved one die, or thinking ahead to how they might die.
What is being proposed?
The End of Life Choice Act gives New Zealanders the option of legally requesting help to end their lives.
To be eligible, they have to be 18 years or older, a New Zealand citizen or permanent resident, and suffer from a terminal illness that is likely to end their life within six months.
There are further hurdles for eligibility. They need to be in "an advanced state of irreversible decline in physical capability", experience unbearable suffering "that cannot be relieved in a manner that they consider tolerable", and be competent to make an informed decision about dying.
The law also explicitly says a person cannot be eligible for euthanasia on the basis of age, mental illness, or disability alone.
Patients will need the approval of two doctors. One can be their GP and the other must be independent. If either has doubts about the patient's competence, a third opinion must be sought from a psychiatrist.
If at any point a doctor suspects a person is being pressured, they have to stop the process. A doctor also cannot initiate discussion about assisted dying - it must come from the patient.
Doctors must encourage patients to discuss an assisted death with family or friends, but it is not legally required and no sworn witness statements are needed.
Doctors can opt out of the process, but must advise the patient of their right to contact an official registry to get the name of another doctor who will be willing to discuss it.
If the two doctors give the patient the green light, the person has a six-month timeframe to pick a date and time of death. If they change their mind on the day, they can set a new date within that six-month window.
They also choose whether they will do it themselves or be assisted by a doctor, and the method (ingested or injected). They do not get access to the lethal dose of medication, which is handled by the doctor.
A person cannot write an advance directive that they want an assisted death at a later date.
The euthanasia regime would include a registry of willing doctors and a review committee which would report back to government and deal with any complaints.
At the heart of the debate is whether the proposed law change will allow assisted dying to be offered to New Zealanders who want it while preventing vulnerable people from being pressured into dying.
Overseas jurisdictions offer some clues about whether this is possible.
A review of all countries and states' euthanasia laws by a Western Australian select committee in 2018 found that vulnerable groups were not more likely than others to access assisted dying. Analysis of deaths in the United States, Canada and Europe found that those likely to get access it were "older, white and well-educated".
This indicates that legalising euthanasia might not lead to vulnerable people dying in large numbers, but it does not rule it out completely.
The New Zealand law includes protections against coercion but opponents say elderly or disabled people could feel a "duty to die" because they are a "burden" on their caregivers. This is more difficult to safeguard against.
In the US state of Oregon, more than half the people who died through voluntary euthanasia in 2018 cited "burden on family, friends/caregivers" as one of their reasons for choosing to die.
However, it was likely to be one of many factors in choosing to die. More than 90 per cent of people who died also cited loss of autonomy or being unable to engage in activities, which made their life less enjoyable.
There is also concern from within the disabled community that making a group of people eligible for assisted dying sends an alarming message to the most vulnerable people in society.
"The previously unthinkable option of assisted suicide now becomes an apparently reasonable response to their illness."
The scope of New Zealand's End of Life Choice Act was significantly narrowed during the parliamentary process, making a much smaller group of people eligible for assisted dying.
The Netherlands allows people as young as 12 to request assisted dying and it is available to non-terminal patients. Belgium has no age limit for children, but they must have a terminal illness to qualify.
Canada and the state of Victoria have similar regimes to New Zealand, limiting euthanasia to terminal people with six months to live - although Victoria extends that threshold to 12 months if the person has a degenerative neurological condition.
Canada is now deciding whether to broaden its law to non-terminal patients, which has led some anti-euthanasia groups to warn about the "slippery slope" of legalisation.
Supporters of the End of Life Choice Act say that doesn't foreshadow what could happen here. Those changes were specific to Canada's constitution and law-making. Any further changes to New Zealand's law would need to get through Parliament.
The Western Australia select committee found no evidence of an inevitable "slide" into broader euthanasia laws among countries that have legalised. Any reforms were deliberate and considered, it said.
Officials have not forecast how many people might opt for assisted dying in New Zealand if it were legalised.
But in countries where voluntary euthanasia regimes are well-established, assisted deaths gradually rise to a level of around two per cent of all deaths. In New Zealand, that would amount to about 650 deaths a year.
Claims that legalising euthanasia leads to increased suicide rates do not appear to stack up. In European countries that have legalised euthanasia, suicide rates have remained the same or fallen.
The international experience of euthanasia can tell us only so much. Experts stress New Zealand has unique social, cultural, political and other factors that would influence how this country could respond to a legalised framework.
At a glance
The referendum question will be: "Do you support the End of Life Choice Act 2019 coming into force?" This piece of legislation has already been passed by Parliament, but needs majority public support to come into force.
The act would allow a person with a terminal illness to request assisted dying. To be eligible, they would need approval from two doctors who must apply safeguards, which include competency and no evidence of coercion.
• Yes, I support the End of Life Choice Act 2019 coming into force.
• No, I do not support the End of Life Choice Act 2019 coming into force.
The referendum is binding. If a majority of voters choose "yes", the law will come into force a year after the election (October 2021). If a majority of voters choose no, the status quo will remain.
For:
• Allows people to die with dignity and without extreme suffering. • Gives them control over when and how they die. • Safeguards will prevent vulnerable or disabled people from being pressured into ending their lives. • There is no evidence of a "slippery slope": laws can be broadened only with public and political support. • Polls consistently show majority public support for voluntary euthanasia in NZ.
Against:
• Vulnerable, disabled elderly could be pressured to end their own lives. • Some people could feel a "duty to die" because they believe they are a burden. • Assisted dying could be used to save healthcare costs and could worsen discrimination against Māori and Pacific people. • The law could be broadened to cover more groups, such as mentally ill or younger people. • There is no "cooling down" period so patients may end their life on a whim.
The former legal academic and disability advocate, who has multiple sclerosis, is hospitalised once or twice a year. She has a history of depression and has made multiple suicide attempts.
"In January I was suddenly so ill, lost a bit of weight, couldn't eat, couldn't drink, infections, I was really, really sick. They had said to me if I hadn't got to the hospital within six hours, chances are I was going to be irreversibly sick."
Hickey, who lives in Auckland, says her condition would likely make her eligible for assisted dying under the End of Life Choice Act. But she is strongly against the law change and will vote "no" in the referendum.
One of her concerns was the difficulty in estimating whether someone would die within six months, which is one of the proposed law's safeguards.
Medical experts in New Zealand say clinicians are wrong in predicting death within six months 25 per cent of the time. Cancer prognosis in particular is becoming less certain as more effective therapies are developed for treatment.
Hickey said she believed that it could put Māori and disabled people at risk. Public health systems rationed care for conditions like kidney failure, which affected Māori and Pacific people at a greater rate, she said.
"If we're underfunding healthcare and we don't a cultural lens for palliative care, then people will choose euthanasia out of desperation, not really out of real choice.
"Until you have address health inequities, until we have that equal playing field, not all people will freely choose."
(The law's sponsor, Act leader David Seymour, rejects this argument, saying the most privileged people are the most likely to access euthanasia because they are able to navigate the health system and jump over the multiple bureaucratic hurdles.)
Hickey said there was a dark history in New Zealand of Māori having medical treatment withdrawn against their wishes.
She cited two controversial cases: Rau Williams, who died in 1997, and Robert Ngamu, who died in 2010. In both cases, the men died after hospital medical staff defied their wishes and withdrew treatment.
"Some are saying that Māori are quite safe under this new bill," she said.