Legal glossary

Plain-English definitions of the terms used on CaseTrail and in Supreme Court decisions. These are general explanations for readers, not legal advice.

Affirm

To leave the lower court’s decision in place. When the Supreme Court affirms, the party that won below keeps its win.

Appeal (mandatory jurisdiction)

A route to the Supreme Court that, for certain kinds of cases, the Court was required to decide. Congress eliminated almost all of these in 1988, so nearly every case now comes by certiorari.

Certiorari (cert)

An order by which the Supreme Court agrees to review a lower court’s decision. A party files a petition for a writ of certiorari; the Court grants only a small share of them, traditionally when at least four Justices vote to hear the case.

Chief Justice

The head of the Supreme Court. Historians and the Supreme Court Database group the Court into eras by Chief Justice — for example, the Warren Court.

Concurring opinion

An opinion by a Justice who agrees with the outcome. SCDB separates a regular concurrence (agreeing with the majority’s opinion too) from a special concurrence (agreeing with the result but not the reasoning).

Decree

A formal order of the Court, most often in original-jurisdiction cases such as boundary or water disputes between states.

Dissenting opinion

An opinion by a Justice who disagrees with the outcome. Dissents do not change the result, but they are often cited later.

Docket number

The number the Clerk assigns to a case when it is filed, such as 22-451. It is the easiest way to look a pending case up on the Supreme Court’s website.

Equally divided Court

When an even number of Justices take part and split evenly, the lower court’s judgment is affirmed, but the decision sets no precedent.

Held unconstitutional

A ruling that a law or government action violates the U.S. Constitution and cannot be enforced. SCDB records whether a decision struck down an act of Congress, a state law, or a local ordinance.

Judgment of the Court

Used when a majority agrees on the outcome but not on one set of reasons. The lead opinion that announces the result is often called a plurality opinion.

Majority opinion (opinion of the Court)

The opinion joined by a majority of the Justices. Its reasoning is binding precedent. When the Chief Justice is in the majority, he assigns who writes it; otherwise the most senior Associate Justice in the majority does.

Mootness

A case is moot when events have resolved the dispute, so there is nothing left for the court to decide.

Natural court

A period during which the Court’s membership stays the same. A new natural court begins whenever a Justice joins or leaves.

Original jurisdiction

The small set of cases the Supreme Court hears first, without a lower-court decision — mainly disputes between states.

Overrule

When a court expressly declares that one of its earlier decisions is no longer good law. SCDB records when a decision formally alters precedent.

Per curiam

Latin for “by the court.” An opinion issued in the name of the Court as a whole, without a named author. Many are short rulings issued without oral argument.

Petitioner

The party that asked the Supreme Court to review the case — usually the party that lost in the lower court.

Precedent (stare decisis)

The principle that courts follow earlier decisions on the same legal question. Supreme Court precedent binds all lower courts on questions of federal law.

Remand

To send a case back to a lower court for further proceedings consistent with the Supreme Court’s decision.

Respondent

The party on the other side from the petitioner — usually the party that won in the lower court.

Reverse

To overturn the lower court’s decision. It is often paired with a remand.

Slip opinion

The first official version of an opinion, released the day a decision is announced. It is later replaced by the version printed in the United States Reports.

Standing

The requirement that a party bringing a lawsuit has suffered a concrete injury that a court can remedy. Without standing, a federal court cannot decide the case.

Supreme Court Reporter (S. Ct.) and Lawyers’ Edition (L. Ed.)

Unofficial, commercially published reports of Supreme Court decisions. They are cited when a U.S. Reports page number is not yet available.

Term

The Supreme Court’s working year. It begins on the first Monday in October and is named for the year it begins, so the October Term 2024 decisions mostly came out in 2025.

United States Reports (U.S.)

The official printed reports of Supreme Court decisions. A citation such as 347 U.S. 483 means volume 347, page 483.

Vacate

To set aside the lower court’s judgment, usually so the lower court can reconsider the case — often in light of a new Supreme Court decision.

Writ improvidently granted (DIG)

A dismissal after the Court has agreed to hear a case, used when the Justices conclude they should not have taken it.

Writ of habeas corpus

A court order requiring the government to justify holding someone in custody. Federal habeas petitions are a common way state and federal prisoners challenge convictions.