The Supreme Court is nine justices, one marble building, and the final word on what the Constitution means. Its decisions shape abortion access, voting rights, gun laws, immigration, healthcare, free speech, and the limits of presidential power. Understanding how it works — and one surprising fact most people do not know — gives you the full picture of one of the most consequential institutions in American life.
The Fact Most People Do Not Know — The Size of the Court Has Changed Seven Times
The Constitution does not specify how many justices the Supreme Court must have. It says nothing about the number at all. Congress decides the size of the Court by statute — and Congress has changed it seven times throughout American history.
The Court began with six justices in 1789. Congress reduced it to five in 1801 — a political move by the outgoing Federalist Congress to deny incoming President Jefferson an appointment. Congress increased it back to six in 1802, then to seven in 1807, to nine in 1837, to ten in 1863 — to give President Lincoln more favorable votes during the Civil War — and then back down to seven in 1866 to deny President Andrew Johnson appointments. Congress raised it back to nine in 1869, where it has remained ever since.
In 1937, President Franklin Roosevelt proposed expanding the Court to fifteen justices after it struck down several New Deal programs. Congress rejected the plan — but the debate over court size has never fully gone away. Today the number nine feels permanent and constitutional. It is neither. Congress can change it by passing a law.
How the Court Works
The Supreme Court receives approximately 7,000 to 8,000 requests for review each year — called petitions for certiorari. It agrees to hear roughly 60 to 80 cases. At least four of the nine justices must vote to hear a case for it to be accepted — this is called the rule of four.
Once the Court accepts a case, both sides submit written arguments called briefs. The Court holds oral arguments — typically 30 minutes per side — where justices ask questions directly. The justices then meet in private conference to discuss and vote. The chief justice, if in the majority, assigns who writes the majority opinion. If the chief justice is in the minority, the most senior justice in the majority assigns the opinion.
Justices who agree with the outcome but for different reasons can write concurring opinions. Justices who disagree write dissenting opinions. Dissents have no legal force — but they often become the basis for future majorities. Justice Ruth Bader Ginsburg's dissents in voting rights cases were cited decades later by advocates working to restore those protections.
Who the Justices Are
There are currently nine justices. Six were appointed by Republican presidents and three by Democratic presidents. Justices serve for life — the average tenure in recent decades has been approximately 26 years. A single president can shape the Court's direction for a generation. President Trump appointed three justices in his first term alone — Neil Gorsuch, Brett Kavanaugh, and Amy Coney Barrett — cementing a 6-3 conservative majority that has issued landmark rulings on abortion, gun rights, presidential immunity, and administrative law.
Why Its Decisions Affect Your Daily Life
Supreme Court decisions are not abstract legal arguments. They determine whether your employer can fire you for your sexual orientation, whether the police need a warrant to search your phone, whether students can pray at school events, whether the government can regulate carbon emissions, whether states can restrict abortion access, and how congressional districts must be drawn. The cases that reach the Supreme Court involve the most contested questions in American law — and its answers are final unless the Court reverses itself or Congress amends the Constitution.
SCOTUSblog at scotusblog.com provides plain-language coverage of every Supreme Court case and is trusted across the political spectrum. The Court's own opinions are published at supremecourt.gov.