Groups representing thousands of psychologists are rebelling against rule changes that many fear will make it even harder for patients to get help.
The Psychologists Board - the registering body - is proposing changes that mean some of them could be restricted in the types of conditions they are able to treat.
Critics say patients could miss out, with the country already struggling with a dire shortage of care.
There were currently five main scopes of practice - clinical, educational, neuropsychological, counselling and general psychology - and two trainee ones.
It was up to each psychologist to determine whether they were competent to work in any of them, based on their own training and practical experience, with many working across several scopes.
But the proposal aimed to lock them in more to registration in specific scopes, restricting their ability to practice outside of them.
The Psychological Society represented 2100 psychologists in different fields and opposed the changes.
Executive director Veronica Pitt said the board was well-intentioned, but the changes went too far.
"Psychologists generally do try and follow the rules so it is likely to mean there will be fewer psychologists available to the public and people will miss out on services that they desperately need," she said.
Among the changes proposed was one that would mean only clinical psychologists would be able to make complex mental health assessments and diagnoses.
The board also wanted to create new scopes - forensic, behavioural, child and family, health and industrial.
Opponents argued that would further restrict what individual psychologists were able to do and who they could care for.
"Our concern is that those who have trained in one area but, through experience and professional development and supervision, have increased their practice to work across a lot of different areas will be prevented from doing so - which will mean that the public will miss out," Pitt said.
The College of Clinical Psychologists also strongly opposed the changes, labelling them poorly evidenced, overly restrictive and based on misleading information.
College strategic advisor Paul Skirrow said they were creating a lot of anxiety.
"Lots of people have extended their scopes, extended what they do, and now there's talk of changing that, a lot of people are thinking 'have I been acting improperly' and 'am I not going to be able to do this work I've been doing for years,'" he said.
Skirrow said he understood the board was trying to protect the public.
"You wouldn't want an organisational psychologist diagnosing ADHD, for instance, and you wouldn't want a educational psychologist diagnosing schizophrenia when that's not really the training they've had," he said.
But there was actually no evidence there had been any risk to the public from people acting in that way, he said.
A group of psychologists had banded together to oppose the changes - creating the sunlight.org.nz website to encourage others to make submissions.
The site said some psychologists were already missing out on work because of the changes which made it seem like some psychologists had been acting illegally when that was not the case.
"And all of this is happening at a time when New Zealand continues to be in the midst of a mental health crisis, with people in distress struggling to find psychologists with availability to help them," it said.
Board chief executive Vanessa Simpson declined a request for an interview, saying the board was not in the position to comment while the consultation was underway.
On its website it said it would particularly consider feedback on concerns about who could make complex mental health assessments.
It had extended its consultation period until May.
RNZ
