Defence lawyers say fixed fees for legal aid work will end up costing the Government more.
From March, instead of being paid by the hour, lawyers will be paid a fixed amount for completion of specific work.
The Criminal Bar Association says payment for legal aid work will decrease by up to 45%.
It says ironically the exercise in reducing costs will drive experienced practitioners away and give rise to more litigants representing themselves.
That will potentially lead to additional miscarriages of justice that will, in the end, cost the justice system more.
But the ministry says hourly fees will continue to be paid for serious cases and it is confident practitioners will stay with legal aid work.