The Law Society says a proposal in Family Court reforms to exclude lawyers from the court will place an intolerable burden on judges.
Justice Minister Judith Collins announced changes in August 2012, estimated to save about $70 million over four years.
Among a number of criticisms of the reforms, the Law Society is concerned by a plan to exclude lawyers from hearings on the basis they add cost, time and complexity to the cases.
President Jonathan Temm said cases that end up in the Family Court are the most difficult to resolve.
Mr Temm said intractable disputes where the sides are representing themselves will be extremely difficult for judges to try to cut through.