A therapist who specialises in youth suicide is concerned not enough is known about how assisted dying may affect vulnerable youth.
The End of Life Choice Bill allows for people in unbearable suffering or with an incurable, grievous condition to ask a doctor to help end their life.
Dion Howard, a nurse and therapist who has spent 20 years working with young people and has expertise in adolescent mental health, wrote a submission to MPs considering the bill.
In his submission, he argued the ripple effects on youth had not been adequately explored.
"Really, my question to the select committee is, 'Can you be certain this would not impact the suicide rates of young people?' To which the answer I'm certain is, 'We don't know that'.
"So, the next question should be, 'Well, shouldn't we know or shouldn't you be certain before supporting a change?' "
He said overseas jurisdictions had grappled with the same issue.
"It was quite remarkable that the Scottish Parliament rejected their similar bill on the basis that they didn't think they could reasonably prevent and educate on the prevention of suicide and present it as a solution at the same time.
"We need to be cautious about this and we have good grounds to be cautious."
The bill's author, Act leader David Seymour, said if it passed its second reading later next month, he would restrict it to cover only people with six months to live.
However, Mr Howard said the conversation around dying as a way out remained.
He said many of the young people he worked with were intelligent and articulate, and followed discussions around the bill.
Some were using the justifications of euthanasia advocates to inform their own situations.
However he said some coverage of the bill had glorified assisted dying.
"I've had instances of young people quoting Exit International methods on how to take your own life, which became a part of our risk assessments of their situations. That was concerning to me."
"We have restraints in the media around how suicide is discussed but, in this instance, it is widely discussed as a solution."
Renee Joubert, from Euthanasia-Free New Zealand, said the bill confused the suicide-prevention message.
She said it was usually psychological suffering, not physical problems, that made someone think they would be better off dead.
"The other night we received a call from someone saying, 'I'm suicidal, can you give me euthanasia pills?' Because they thought that was the service we offered.
"Some of these people tell us that they are lonely, that they've got broken relationships, that they feel afraid of the future and it may be further along in the conversation that it comes out that they are physically ill."
"So, it's clear that their main reason for wanting to die is emotional ... psychological."
She said it was too difficult to discern whether an ill person wished to die because of their illness or because they were suicidal.
She said for this reason alone legalised assisted dying was too risky.
"There are studies that show that depression is very prevalent, so people have good days and bad days - depression is part of the grief process involved with having a terminal illness.
"The fact that people request assisted dying for mainly psychological and existential reasons makes the line between assisted dying and suicide very blurry because it could be those exact reasons that motivate a person to attempt suicide.
"So, as a society, if we want to prevent suicide, it would make no sense to facilitate suicide for people who want it for the same reason."
But former head of the End of Life Choice Society and intensive care doctor Jack Havill said there was no proof assisted dying legislation impacted suicides. They were different things that happened under different circumstances, he said.
"In Switzerland and in Luxembourg and Belgium, the suicide rates have decreased. In Oregon and the Netherlands, the rates are reasonably high but they're not higher before the legalisation of end of life choice."
He said while he could see where the concern came from, the evidence simply was not there.
Mr Howard disagreed.
"There's no clear evidence either way to say that it would have an impact.
"David Seymour is good at dismissing it as a red herring but given our context in New Zealand, I would expect that we should be more certain than giving no evidence either way."
The bill will go through its second reading in parliament on 22 May.
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