In English Law certiorari is a public law relief (i.e. something which you
ask the court for to deal with an action of the Government, council or other
(quasi)-governmental organisation.) See judicial review and writ. An order
of certiorari is given by a senior court to reverse the actions of a lower
court or other (quasi)-governmental organisation which has made a decision.
Its use in the UK is declining, due to the changes to the remedies available
for judicial review.
Historically, certiorari was a prerogative writ used to direct a lower court
or tribunal to certify for review the "record" in the case.
In the U.S., certiorari is the writ that an appellate court issues to a
lower court in order to review its judgment for legal error, where no appeal
is available as a matter of right. Since most cases cannot be appealed to
the U.S. Supreme Court, for example, a party who wants that court to review
a decision of a federal or state court files a "petition for a writ of
certiorari" in the Supreme Court. If the court grants the petition, the case
is scheduled for briefing and argument. That does not necessarily mean the
Supreme Court has found anything wrong with the decision, merely that it
wants to look at it for some reason. Four of the nine justices must vote to
grant a writ of certiorari. The great majority of cases brought to the
Supreme Court are denied certiorari, because the Supreme Court is generally
careful to choose only cases in which it has jurisdiction and which it
considers sufficiently important to merit the use of its limited resources.
Certiorari is sometimes informally referred to as cert, and cases warranting
the Supreme Court's attention as certworthy. One situation where the Supreme
Court sometimes grants certiorari is when the federal appeals courts in two
(or more) federal judicial circuits have ruled different ways in similar
situations, and the Supreme Court wants to resolve that "circuit split"
about how the law is supposed to apply to that kind of situation.
Some U.S. state court systems use the same terminology, but in others, writ
of review or leave to appeal is used in place of writ of certiorari as the
name for discretionary review of a lower court's judgment.
In the administrative law context, the common-law writ of certiorari was
historically used by lower courts in the U.S. for judicial review of
decisions made by an administrative agency after an adversarial hearing.
Some states have retained this use of the writ of certiorari, while others
have replaced it with statutory procedures. In the federal courts, this use
of certiorari has been abolished, and replaced by a civil action under the
Administrative Procedure Act in a United States District Court, or in some
circumstances, a petition for review in a United States Court of Appeals.