The Criminal Bar Association is worried the Government's plans to unclog the court system will not address the problems that cause lengthy delays.
Under the changes, defendants charged with an offence that carries a prison sentence of up to three years would be tried before a judge rather than having the option of a jury trial.
At the moment, anyone accused of an offence that carries a prison term of three months or more can opt for a trial by jury.
Justice Minister Simon Power says up to 1,000 jury trials a year could be spared if that threshold was increased to three years.
Criminal Bar Association president Anthony Rogers says resources should instead be put into resolving problems like overbooked courts and untimely disclosure of documents, which result in the inevitable delay in proceedings.
Barrister Barry Hart is worried the changes could impinge on a person's fundamental right to be tried by their peers.
Labour's associate justice spokesperson, Charles Chauvel, told Morning Report the right to a jury trial is an important guarantor of people's rights, and any tinkering with it must deliver New Zealanders greater access to the justice system as a whole.
Further changes planned
Mr Power said on Sunday that if his preferred system went ahead there would be no need to employ more judges or build more courthouses.
He said the average waiting time for a District Court jury trial is 12 months.
Among other changes, Mr Power wants convictions to go ahead if defendants fail to turn up for court hearings, as long as a plea has already been entered.
He wants lawyers to deal with cases in a more timely fashion, saying the culture whereby delay is viewed as a legitimate tactic by counsel on both sides of criminal cases must change.
Mr Power believes the public is tired of cases being delayed because lawyers are not doing the job and would consider imposing sanctions, including fines, for lawyers who do not comply.
The Government hopes to make the changes before the next election.