A discretionary remedy used in judicial review available in the original jurisdiction of the High Court under section 75(v) of the Constitution, in the Federal Court under section 39B(1) of the Judiciary Act 1903 (Cth) and to a limited extent in some state courts.

A writ of certiorari effectively quashes past conduct for which there was no jurisdiction, for example to quash a decision of a federal superior court. It lies against bodies or persons exercising public power.

It is in essence a two part remedy:

A writ of certiorari is an ancillary remedy and will be issued only where another constitutional remedy is established. It may issue ancillary to a writ of mandamus or writ of prohibition (Heli-Aust Pty Ltd v Cahill [2011] FCAFC 62 at [190]).

In order to obtain certiorari an applicant must establish jurisdictional error (Central Queensland Services Pty Ltd v Construction, Forestry, Mining and Energy Union [2017] FCAFC 43 at [44]). There has been some controversy as to whether, unlike for a writ of prohibition, the court may grant a writ of certiorari to quash a decision for error of law on the face of the record falling short of jurisdictional error. See Construction Forestry Mining and Energy Union v Director of the Fair Work Building Industry Inspectorate [2016] HCA 41 at [35] where the High Court assumed that a writ of certiorari was available for non-jurisdictional error on the face of the record, without deciding the matter.

Certiorari lies only to quash a "determinative" decision. Certiorari is unlikely to be available where the decision maker was only hearing argument and answering questions without making orders binding on the parties (Central Queensland Services Pty Ltd v Construction, Forestry, Mining and Energy Union at [45] and [49]).

In some cases, the court may choose to grant an equitable remedy, such as an injunction or declaration, instead of a writ of certiorari. See for example Heli-Aust Pty Ltd v Cahill at [194]. In other cases, it will be necessary to formally quash a decision by writ of certiorari, such as a decision imposing a licence.

Writs of certiorari, mandamus and prohibition are now known as constitutional writs, although for centuries they were known as prerogative writs (Re Refugee Review Tribunal; Ex parte Aala (2000) 204 CLR 82; [2000] HCA 57).

For further information about judicial review of administrative decisions see Practice note, Appeals from non-judicial bodies: overview.