What is natural justice?

Natural justice in Australian law is the set of common-law principles requiring decision-makers to act fairly when their decisions affect a person's rights, interests, or legitimate expectations. The principles are ancient, dating back to medieval English common law, and continue to operate today as the baseline for fair government and judicial decisions in Australia.

Two main rules make up natural justice. The hearing rule (audi alteram partem, hear the other side) requires that a person who will be affected by a decision be given fair notice of the case against them and a reasonable opportunity to be heard. The rule against bias (nemo iudex in causa sua, no one shall be a judge in their own case) requires that the decision-maker be free of personal interest in the outcome and free of conduct that would lead a reasonable observer to apprehend bias.

Natural justice applies across many Australian decision-making contexts. Courts operate under the rules as a matter of course. Administrative tribunals (the Administrative Appeals Tribunal, fair work commissions, immigration review tribunals, state civil and administrative tribunals) must observe natural justice subject to specific statutory adjustments. Government decisions affecting individuals (visa refusals, license cancellations, social security debt assessments, public service disciplinary action) must follow natural justice unless Parliament has expressly excluded it. Decisions by professional bodies and even by some private organisations can be subject to natural justice if they affect significant interests.

When natural justice is denied, the affected person can seek judicial review. The Federal Court, the Federal Circuit and Family Court, and state and territory supreme courts can quash decisions that have been made without procedural fairness and order rehearings. The Administrative Decisions (Judicial Review) Act 1977 (Cth) and equivalent state legislation set the framework. Common remedies include orders of certiorari (quashing the original decision), mandamus (compelling a fresh decision), and declaration. The Robodebt Royal Commission of 2023 documented major failures of natural justice in the automated income-averaging system that operated from 2016 to 2019, leading to substantial reforms in how Centrelink decisions are made and communicated.