A word from Law Latin, meaning "to be more fully informed." In the United States, certiorari is most commonly associated with the writ that the Supreme Court of the United States issues to review a lower court's judgment. An appellate court may use certiorari as the formal instrument by which to review cases at its discretion. A case cannot, as a matter of right, be appealed to the U.S. Supreme Court; therefore, a party seeking to appeal from a lower court decision may file a petition to a higher court for a writ of certiorari. The appellate court may then order a lower court to deliver its record in a case so that the higher court may review it.
The Supreme Court of the U.S. gives full consideration to but a small fraction of the cases it has authority to review. With many important categories of cases, the party seeking Supreme Court review does so by "petitioning" the Court to issue a "writ of certiorari." (See, e.g., 28 U.S.C. §§ 1254, 1257, 2350.) (Note: Some state appeals courts -- e.g., Ala., Ark., Colo., Conn., Fla., Ga., La., N.J. -- employ the same terminology.) If the Court decides to review one or more issues in such a case, it grants certiorari (often abbreviated as "cert."); if the Court decides not to review the case, it denies certiorari. A decision to deny certiorari lets the lower court's ruling stand. The Supreme Court will only grant certiorari for compelling reasons, including but not limited to the circumstances listed in Supreme Court Rules, Rule 10.
The decision to grant or deny certiorari is discretionary. A decision to deny certiorari does not necessarily imply that the higher court agrees with the lower court's ruling; instead, it simply means that fewer than four justices determined that the circumstances did not warrant a review by the Supreme Court according to long-standing internal Court practice. The Court's orders granting or denying certiorari are issued as simple statements of actions taken, without any explanations given for denial. It has been suggested that the Court indicate its reasons for denial. In Maryland v. Baltimore Radio Show, Inc., however, the Court explained that because of practical considerations (to allow the Court to carry out its indispensable duties), Congress has allowed the control of the Court's business to remain within the Court's discretion.
Originally, the writ of certiorari was a proceeding through which a superior court required a lower court to submit the full record of a case for review. Under the current rules and practice of the Supreme Court, however, key elements of the proceedings below are submitted along with a petition for certiorari. (See Supreme Court Rules, Rule 14.) And in some states the old terminology has been replaced. In Arizona, for example, relief formerly obtained by the writs of prohibition, mandamus and certiorari is now obtained through a "special action."