The Chief Ombudsman says the Government's plans to exclude charter schools from legislation including the Official Information Act are unconstitutional.
The Education and Science select committee began hearing submissions on Wednesday on the Education Amendment Bill that will introduce the publicly-funded private schools.
If passed, it will create charter or partnership schools and water down schools' right to conduct drug searches.
The Government intends to have charter schools open by the start of the next school year. The National Party agreed to establish charter schools under its support deal with ACT.
The schools will receive public funding, but won't have to follow the New Zealand curriculum, or be required to employ registered teachers.
The bill exempts partnership schools from the Ombudsman's Act and the Official Information Act, but Dame Beverley Wakem told the select committee that is unconstitutional.
Dame Beverley said the acts ensure that state-funded agencies are accountable and people have a fundamental right to the complaints process provided by the Office of the Ombudsman.
Other submissions from the groups including the Principals Federation, the Educational Institute and the National Council of Women strongly opposed the creation of partnership schools under any conditions.
They said the Government has no mandate for the policy and there is no evidence the schools will raise education standards.
Groups also criticised the changes to schools' ability to search students for drugs and weapons.
The Green Party says if in a position to do so, it would integrate charter schools into the public school system. Co-leader Metiria Turei believes they are a waste of money and will not improve New Zealand's school system.
More submissions will be heard in March.