The Law Society says proposed changes to legal aid for accident compensation cases will hit vulnerable people.
The Ministry of Justice has already proposed fixed fees for legal aid in criminal and family cases and now wants to use the same system for ACC claimants.
The Law Society says there are only 13 lawyers who regularly provide legal aid work in this area and there is a risk many will cease to do it if the cuts go through.
President Jonathan Temm says that will affect vulnerable people who have serious injuries and complex medical and social problems.
Mr Temm says the savings from fixed fees will be minimal, as the net cost of ACC legal aid last year was only $1 million.
The Ministry of Justice says the proposal is one of several changes to make the legal aid system more sustainable and it will make a final decision on the fixed fee rates in April.