New Accident Compensation Corporation guidelines for victims of sexual abuse came into force on Tuesday, but are opposed by clinicians who believe it will be harder for people to get treatment.
The corporation says it is legally required to concentrate only on those who suffer a diagnosed mental injury as a result of sexual abuse.
A petition opposing the new sensitive claims policy signed by 4000 people was presented at Parliament on Tuesday.
Petition organiser Kyle MacDonald, from the Association of Psychotherapists, says the new guidelines will make it harder for victims to get treatment.
Mr MacDonald says a number of counsellors, psychologists and psychotherapists are saying they will refuse to work under the new guidelines.
"The Government has repeatedly said that this decision is going to be made by clinicians, not politicians.
"Yet the overwhelming majority of people who have signed this petition are psychotherapists, counsellors, social workers and psychologists who believe these guidelines to be both unethical and not following best practice."
System to be reviewed
ACC Minister Nick Smith says he has confidence in the way ACC handles sensitive claims.
However, Dr Smith says he has requested that ACC undertake an independent clinical review of the new process in six months' time to ensure there is public confidence in the new system.
The Labour Party says the Government should put the guidelines on hold, rather than just review them.