How does the Supreme Court work? Cases, justices, rulings

The Supreme Court is the highest court in the United States, and most of what it does is choose: its work starts with deciding which cases to hear. Each year several thousand losing parties ask it to hear their case; four of the nine justices must agree to take one, and it takes fewer than one in fifty. For those, it reads briefs, hears an hour of argument, votes in private and publishes opinions. A majority of five decides, and its reading of the Constitution binds every other court.

In short

• The Court mostly hears appeals it chooses to take, through a petition called certiorari, and four justices must vote to take a case.
• Its biggest power, judicial review, lets it strike down laws that break the Constitution. The Court claimed it in 1803.
• Justices are nominated by the president, confirmed by the Senate and serve for life, so the Court changes slowly and unevenly.

Where does the Supreme Court's power come from?

Article III of the Constitution creates "one supreme Court" and leaves almost everything else to Congress. It says judges hold office "during good Behaviour", which in practice means for life, and that their pay can't be cut. It doesn't set the number of justices. The Judiciary Act of 1789 set it at six, and Congress changed it several times before fixing it at nine in 1869, where it has stayed.

The Court's most important power isn't written in the Constitution at all. In Marbury v. Madison in 1803, Chief Justice John Marshall wrote that "it is emphatically the province and duty of the judicial department to say what the law is", and that a law contrary to the Constitution is void. That power, judicial review, is what lets nine unelected judges overturn the work of Congress, the president or a state. Every major ruling since rests on it.

How does a case get to the Supreme Court?

Almost every case starts somewhere else, in a state court or a lower federal court, and reaches the Supreme Court only after someone has lost an appeal. The loser then files a petition for a writ of certiorari, Latin for "to be informed", asking the Court to review the decision. The Court has no duty to say yes, and it almost always says no.

Each week the justices and their clerks screen about 130 petitions, by the Court's own count. Most justices share the first reading through a "cert pool", in which one clerk writes a memo on each petition for several justices. The justices then discuss the strongest in a private conference. By a custom called the rule of four, four votes out of nine are enough to grant review, one fewer than it takes to win. The Court looks for cases where lower courts disagree on what federal law means, where a lower court struck down a federal law, or where the question is important nationally. Whether the lower court got it wrong is, on its own, rarely enough.

A tiny set of cases, mostly disputes between states, go straight to the Supreme Court under what is called original jurisdiction. Water rights between neighboring states are a common example.

The numbers for one term

The Court's own figures show how narrow the funnel is. In the term that began in October 2024, according to the Chief Justice's year-end report:

Step	Cases
Petitions and other cases filed	3,856
Of those, from people too poor to pay the filing fee	2,527
Cases argued before the justices	73
Argued cases decided by signed opinion	64, in 56 opinions

That is 73 argued out of 3,856 filed, or about 1.9%, roughly 1 in 53. In the 2023 term, 4,223 cases were filed and 69 argued. Filings have fallen over the long run; through much of the 2000s and 2010s the Court received 7,000 or more a year.

What happens once the Court takes a case?

A term begins by law on the first Monday in October, and arguments run until late April. First come written briefs from each side, often joined by friend-of-the-court briefs, called amicus briefs, from outside groups and governments. Then comes oral argument, usually an hour per case and 30 minutes per side. The justices interrupt constantly, so argument is less a speech than a cross-examination of the lawyer's weakest points.

Within days, the nine meet alone in conference, with no clerks or staff in the room, and vote in order of seniority. If the Chief Justice is in the majority, he assigns who writes the opinion of the Court; if not, the most senior justice in the majority does. Drafts then circulate for weeks or months, and votes can change before release. The biggest rulings usually come out in June, at the end of the term.

A decision can produce several opinions. The majority opinion states the holding and binds lower courts. A concurring opinion agrees with the result but gives different reasons. A dissent explains why a justice disagrees, and some dissents later become the law: Justice John Marshall Harlan's lone dissent in Plessy v. Ferguson in 1896 was vindicated when Brown v. Board of Education ended legal school segregation in 1954. If the vote ties, for example 4–4 because a justice stepped aside, the lower court's ruling stands.

One case, start to finish

Clarence Earl Gideon, charged with breaking into a Florida pool hall, asked for a lawyer and was refused because he couldn't pay. From prison he wrote his own petition in pencil. The Court granted review in June 1962, appointed the Washington lawyer Abe Fortas to represent him, heard argument on 15 January 1963, and on 18 March 1963 ruled in Gideon v. Wainwright that states must provide lawyers to defendants in serious criminal cases who cannot afford one. The Court used the 14th Amendment to apply that right to the states. Retried with a lawyer, Gideon was acquitted.

How are Supreme Court justices chosen?

When a seat opens, by death, retirement or, in theory, impeachment and removal, the president nominates a replacement, and the Senate decides. The Senate Judiciary Committee holds hearings where the nominee answers questions, then the full Senate votes. Since 2017, when the Senate changed its rules, ending debate on a Supreme Court nomination needs only a simple majority rather than 60 votes, which also ended the filibuster for these nominations.

Life tenure means the timing of vacancies, not a schedule, decides how many seats each president fills. Some presidents have appointed none in a full term; others have appointed three or more. A justice can be removed only by impeachment in the House and conviction by two-thirds of the Senate. Only one has been impeached, Samuel Chase in 1804, and the Senate acquitted him in 1805. Chief Justice John Roberts has led the Court since 2005. The court's makeup can change at any vacancy, so any count of who sits there needs a date.

What checks are there on the Supreme Court?

The Court has no army and no budget of its own; it relies on the other branches to carry out its rulings. Congress can change the number of justices, limit which appeals the Court hears, rewrite a statute the Court has interpreted, or start a constitutional amendment to overturn a ruling, as the 26th Amendment did for the voting age after a 1970 decision. The president chooses nominees, and the Senate confirms them. Over time, those appointments are the main way elections shape the Court. The note on presidential powers shows the same checks from the other side.

Still argued

How much power nine appointed judges should hold in a democracy is a long-running argument. Some argue for reforms such as 18-year term limits or adding seats, saying life tenure makes the Court too dependent on the timing of deaths and retirements and too removed from voters. Others argue that independence from voters is the point, that judges should be insulated from the politics of the moment, and that adding seats would invite each party to add more when it wins power, as critics said of Franklin Roosevelt's failed 1937 plan. There is also a long debate over method, between reading the Constitution by its original meaning and reading it as a document whose application changes with the times. Neither side's proposals have been enacted.

Check yourself

• Without looking back: walk a case from a lower court loss to a Supreme Court opinion, naming each step.
• What is judicial review, and why does it matter that the Court claimed it rather than being given it?
• Why does life tenure make the timing of vacancies so important?

Sources

• Constitution of the United States, Article III — National Archives
• Marbury v. Madison (1803) — National Archives
• The Court and Its Procedures — Supreme Court of the United States
• 2025 Year-End Report on the Federal Judiciary — Supreme Court of the United States, 2025
• Supreme Court Procedures — Administrative Office of the U.S. Courts
• Gideon v. Wainwright, 372 U.S. 335 (1963) — Legal Information Institute, Cornell Law School