Lawyers say people will be more likely to choose to represent themselves in court under changes to legal aid, which are coming into effect.
In an effort to get people to pay their legal aid bills, an interest charge of 8% will be added to outstanding bills from March.
The Justice Ministry estimates 50,000 people, or a quarter of those using the system, are able to pay their legal aid bill.
The spokesperson for lobby group Rethinking Crime and Punishment, Kim Workman, says some lawyers are already advising clients to represent themselves if they cannot afford the interest charge. He says more people will plead guilty because that's the cheapest option.
Criminal Bar Association president Tony Bouchier agrees more people will end up representing themselves.
"People may decide that rather than incurring a debt they'll plead guilty to things that they haven't done," Mr Bouchier says. "Women may be reluctant to apply for legal aid because they are going to occur a debt as a result of going to the Family Court."
However, Legal Services Commissioner Nigel Fyfe says it beggars belief that lawyers would advise clients to represent themselves, or that people would choose to avoid legal aid because of an 8% interest charge.
He says charging interest is expected to recover $80 million in the next four years.