Police have admitted conducting breath-testing in Maungaraki, Lower Hutt, as a ploy to gather information about elderly women attending a nearby euthanasia meeting.

Police have admitted they used a breath-testing checkpoint to target people who had attended an Exit International euthanasia meeting.

The move has been criticised as an "unlawful checkpoint to interrogate pensioners" by one lawyer, while another said it was probably a breach of police powers.

A complaint has already been laid with the Independent Police Conduct Authority about the officers' actions in Lower Hutt earlier this month, and at least one other is likely to be laid in coming days.

ROSS GIBLIN/FAIRFAX NZ Longtime Voluntary Euthanasia Society member Wilhelmina Irving got a visit from police after attending the Exit International meeting in Lower Hutt early in October.

Police said on Wednesday evening that they had also notified the IPCA themselves.

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The police targets, mostly elderly women, had been attending the meeting on a Sunday afternoon early this month in Maungaraki.

FAIRFAX NZ Inspector Chris Bensemann has confirmed the checkpoint ploy, saying police had a duty of care and a "responsibility to the community to investigate any situation where we have reasonable grounds to suspect that persons are being assisted in the commission of suicide".

As they left, about 4pm, all were pulled over at the checkpoint and – before being asked to blow into the machine – were made to give their names and addresses, and show their driver's licences.

In the days that followed, at least 10 of them received visits from police officers, asking questions about their association with Exit, a pro-euthanasia group.

Questions put to police late last week and over Labour Weekend went unanswered. But on Wednesday, Inspector Chris Bensemann supplied a written statement confirming the checkpoint was to "identify people attending an Exit International meeting in Lower Hutt", and was carried out "in good faith and for good reasons".

STUFF Voluntary Euthanasia Society president Maryan Street said police were incompetent and confused about their powers in dealing with the issue of euthanasia. Street plans to file an Independent Police Conduct Authority over the breath-testing checkpoint being used to target people attending euthanasia meeting.

He said police had a duty of care and a "responsibility to the community to investigate any situation where we have reasonable grounds to suspect that persons are being assisted in the commission of suicide".

"Police are responsible for enforcing New Zealand's laws, and currently suicide or encouraging/helping someone to commit suicide is illegal in New Zealand."

He confirmed the operation was conducted via a breath-testing checkpoint near the location of the meeting.

FAIRFAX NZ Human rights lawyer Michael Bott says police "misused their powers".

"We acknowledge that this is a very sensitive issue, and that there is a high level of public interest in the matter.

"Information gathered through the checkpoint has enabled police to provide support and information to those people who we had reason to believe may be contemplating suicide."

Roger Brooking, the Wellington man who has already laid an IPCA complaint, said the operation appeared to be an abuse of police power.

"I think it is a complete and utter waste of police and court resources, and police shouldn't abuse their power to target a group of elderly women who may at some point in the future want to consider suicide."

Elisabeth​ Meylen, one of the women stopped by police after the meeting, called the checkpoint a misuse of power, and said she would also be laying an IPCA complaint.

"I'm appalled they would use that [public] money. Youth suicide is really what they should be concerned about.

"There are a lot of mature women of great wisdom [in Exit]. They should just allow us to be."

Former Labour MP Maryan Street, who is president of the Voluntary Euthanasia Society, said Bensemann was "100 per cent wrong" about the law around suicide.

There was no law against suicide in New Zealand, but it was a crime to help others commit suicide, she said.

She was "deeply angry" to hear that police had confirmed using an alcohol checkpoint to target elderly women, and she planned to file a complaint to the IPCA.

Gathering the information under the pretext of road safety was unlawful, she said. "Breath-testing checkpoints are about road safety, not a covert means of conducting surveillance on political or moral grounds."

ACT leader David Seymour said people had the right to meet and discuss issues without "fear of police harassment".

"The admission that the police used a drink-driving checkpoint to obtain the identities of people attending a meeting is deeply un-Kiwi," he said.

"The police minister needs to explain why peaceful New Zealanders are being interrogated under false pretences."

The "dodgy" operation raised questions about why the checkpoint was organised, he said.

"Who was pushing for this surveillance? What was their motivation? And why were the police minister and solicitor-general not aware of such a politically sensitive operation?

"Somebody has to be accountable."

Human rights lawyer Michael Bott said the police belief that they were acting in good faith did not mean the checkpoint was legal.

It appeared police had set up an "unlawful checkpoint to interrogate pensioners", he said.

"Police, in this, think they are above the law and are quite prepared to break it when they want to."

Police did not have the right to conduct roadside breath tests with an "ulterior motive" that was outside the Land Transport Act, he said. "They have misused their powers."

CORONIAL INQUIRIES

It is understood police in the Exit International case were originally asked to investigate on behalf of a coroner looking into a death that was suspected to be self-inflicted.

Those inquiries later turned into a criminal investigation, codenamed Operation Painter, under which checkpoint was conducted.

The Department of Justice said on Wednesday that, under the Coroners Act 2006, police investigated sudden deaths on behalf of the coroner.

During the course of a coronial investigation, police sometimes found information that required a separate investigation. In those cases, coroners usually adjourned their inquiries while police investigations were completed.

The department said that, in a recent case, toxicology results from a death referred to the coroner revealed the presence of a particular drug. Police informed the coroner that a criminal investigation would commence.

"This matter is currently subject to a police investigation."