Health authorities have received multiple complaints about the Assisted Dying Service, including a lack of facilities willing to provide it and claims of discrimination against patients with a terminal illness.
Since the End of Life Choice Act came into place two years ago, more than 600 people with a terminal illness have used the service.
Under the legislation, health practitioners can choose whether they are willing to provide their patients who fit the criteria with assisted dying, and if they choose not to, they have to provide patients with another practitioner who is.
Ministry of Health data showed 16 complaints about the service have been received - two of which were referred to the Health and Disability Commission, which has also been investigating another dozen of its own.
Health and Disability Commissioner Morag McDowell said six of the cases have been closed and another eight were still being assessed or investigated.
McDowell said all doctors must abide by the Code of Consumer Rights when dealing with every patient.
"Even if they did object to the service, they have still got obligations to the consumer who has chosen to have an assisted death. That means they have still got to provide advice to seek a doctor who can provide the service and continue to provide quality care."
McDowell said quite a few of the complaints were about alleged discrimination by practitioners and facilities against people approaching them for assisted dying.
"Some facilities weren't really ready to provide the service. For example, they may not have had an appropriate space available. One of the other things we've noticed is what can be described as judgmental attitudes by health professionals towards people who had made that choice for an assisted death."
Palliative care provider Hospice New Zealand said the majority of its facilities choose to not include assisted dying in their care. Chief executive Wayne Naylor said there were moral and ethical issues to consider.
"Hospice staff will do everything to care for the patient, right up to the point where they will have an assisted death. The actual act itself is not a thing that hospices do as it is not part of hospice care."
He said they allowed an external provider to come and do the assessments and the service.
However, Naylor believed there was a shortage of health practitioners who had chosen to be involved as morally, ethically and philosophically it could be very challenging.
A GP who did not want to be named said her practice chose not to provide the service as it sat uncomfortably with them, especially if it was a long-term patient of theirs.
Te Whatu Ora ran the service. Spokesperson Astuti Balram said it had not received any complaints about accessing the end-of-life service and the majority of patients chose to receive it in their own homes.
Balram said the service was being delivered in the approved timeframe, four to eight weeks.
The Ministry of Health said in a statement a growing number of GPs were delivering the Assisted Dying Service, and it would review the End of Life Choice Act next year.