The core jurisdiction of the office is cases of maladministration, but it has been progressively expanded over the years to cover complaints under the Official Information Act 1982 and Local Government Official Information and Meetings Act 1987, whistleblower complaints under the Protected Disclosures Act 2000, and it is one of New Zealand's national preventive mechanisms under the Optional Protocol to the Convention against Torture.

[2] The idea of establishing an ombudsman in New Zealand goes back to early 1961 when the Second National Government circulated a paper proposing to do so, based on the Scandinavian model.

[3] In 1962 Parliament passed the Parliamentary Commissioner (Ombudsman) Act 1962, creating an ombudsmen system based on that of Denmark, with powers to investigate administrative decisions.

[4] Initially the Ombudsman served for a term of three years, and had jurisdiction only over central government agencies.

[4] In 1982 the jurisdiction of the Ombudsmen was expanded again, to cover complaints under the Official Information Act 1982.