The Supreme Court has nine justices because a federal statute passed by Congress in 1869 says so. The Constitution creates the court but never fixes its size, leaving that choice to Congress. Nine has held for over 150 years, but it took seven changes in the court’s first 80 years to land there, and any future Congress could change it again by passing an ordinary law.
The Constitution Leaves the Number to Congress
Article III, Section 1 is remarkably brief about the court it creates: “The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish.”1Library of Congress. Article III Section 1 Nothing about how many justices should serve, how many it takes to decide a case, or how the court should be organized. The Framers handed all of that to Congress.
Congress first used that power in the Judiciary Act of 1789, creating a six-member court with one Chief Justice and five Associates.2Library of Congress. ArtIII.S1.8.3 Supreme Court and Congress – Constitution Annotated The current nine comes from the Judiciary Act of 1869, now codified at 28 U.S.C. § 1: “The Supreme Court of the United States shall consist of a Chief Justice of the United States and eight associate justices, any six of whom shall constitute a quorum.”3Office of the Law Revision Counsel. 28 USC 1 – Number of Justices; Quorum Because the number lives in a statute rather than the Constitution, changing it takes only a bill passed by both chambers and signed by the President. No constitutional amendment required.
How the Number Moved Before It Settled at Nine
Nine feels inevitable now. It wasn’t. Congress changed the court’s size seven times between 1789 and 1869, usually tied to the country’s westward growth and sometimes to raw political fights.
In the early court, each justice was assigned to “ride circuit,” traveling long distances to serve as a trial and appellate judge in the federal circuit courts. The justices complained almost immediately; by 1792 they wrote to President Washington that the duty was “too burdensome” given their age and health.4Federal Judicial Center. A Brief History of Circuit Riding That system tied the number of justices to the number of circuits: every new circuit meant another justice.
Then came the political manipulation. In 1801, the outgoing Federalist Congress passed a law shrinking the court from six to five at the next vacancy, partly to deny incoming President Thomas Jefferson an appointment. The new Republican Congress repealed it in 1802 before any seat opened.5Federal Judicial Center. Landmark Legislation – Judiciary Act of 1801 After that, the court grew with the country: a seventh seat in 1807 for the new Seventh Circuit, two more in 1837 when the Eighth and Ninth Circuits were created, and a tenth in 1863 during the Civil War.2Library of Congress. ArtIII.S1.8.3 Supreme Court and Congress – Constitution Annotated
After the war, Congress reversed course. The Judicial Circuits Act of 1866 shrank the court from ten to seven through attrition, blocking seats as justices retired. The immediate effect was to prevent President Andrew Johnson from filling any Supreme Court vacancies.6Federal Judicial Center. Landmark Legislation – Circuit Reorganization Once Ulysses Grant took office, Congress passed the Judiciary Act of 1869 and set the number at nine.3Office of the Law Revision Counsel. 28 USC 1 – Number of Justices; Quorum It has not moved since.
FDR Tried to Change It and Failed
The most famous challenge to nine came in 1937. After the Supreme Court struck down multiple pieces of his New Deal, President Franklin Roosevelt proposed the Judicial Procedures Reform Bill. It would have let the President appoint one new justice for every sitting justice over age 70 who had not retired, up to six additional seats. The court could have grown to 15.7Federal Judicial Center. FDRs Court-Packing Plan
Roosevelt publicly described the plan as a workload fix. No one was convinced. He wanted justices who would uphold his economic agenda. The backlash was bipartisan and intense, and the bill never passed. Roosevelt lost significant political capital.
Around the same time, Justice Owen Roberts began voting to uphold state economic regulations he had previously struck down, most notably in West Coast Hotel v. Parrish in March 1937. Humorist Cal Tinney called it “the switch in time that saved nine,” and the phrase stuck. Whether Roberts actually shifted because of the court-packing threat is still debated. Either way, the court’s new willingness to uphold New Deal-style laws made the plan politically unnecessary, and Roosevelt let it die.
Why an Odd Number Matters in Practice
Nine is the authorized size, but the court doesn’t always have nine functioning justices on a case. Seats sit empty between confirmations, and federal law requires any justice to step aside when their impartiality could reasonably be questioned, including financial interests, family connections, or prior involvement in the matter as a lawyer or government official.8Office of the Law Revision Counsel. 28 U.S. Code 455 – Disqualification of Justice, Judge, or Magistrate Judge
The statute requires at least six justices to hear a case.3Office of the Law Revision Counsel. 28 USC 1 – Number of Justices; Quorum When one justice recuses and eight hear a case, a 4–4 split leaves the lower court’s decision standing, produces no Supreme Court opinion, and sets no national precedent. The case effectively vanishes. That is one practical reason an odd number helps: at full strength, ties are rare.
Could Congress Change the Number Again?
Legally, yes. The barrier is political, not constitutional. Proposals surface whenever the confirmation process produces results one side considers illegitimate.
In 2021, congressional Democrats introduced the Judiciary Act of 2021, a two-sentence bill that would have replaced “eight associate justices” with “twelve associate justices” in the federal statute, moving the court from nine seats to thirteen.9Senate.gov. Judiciary Act of 2021 Supporters argued thirteen justices would align with the thirteen federal circuit courts of appeals. Democratic leadership in both chambers distanced themselves from the bill almost immediately, and it went nowhere.
That same year, President Biden created the Presidential Commission on the Supreme Court to study reform options. Its final report described “profound disagreement” on expansion. Supporters framed it as a response to broken confirmation norms. Opponents warned it would invite retaliatory packing by future majorities and damage the court’s independence.
Term limits are a different conversation. The most common version would give each justice a single 18-year term, staggered so a vacancy opens every two years and each president gets two appointments per four-year term. The Biden commission found “considerable, bipartisan support” for this approach. The problem is Article III’s “good Behaviour” clause, which the Supreme Court has long read as life tenure.1Library of Congress. Article III Section 1 Most legal scholars believe meaningful term limits would require a constitutional amendment, a far higher bar than changing the court’s size. Some proposals try to work around that by rotating justices to lower federal courts after 18 years rather than removing them from the bench, but whether that structure would survive a constitutional challenge remains open. As of 2026, no term-limits proposal has advanced beyond the hearing stage.
So nine stands, held in place by a statute Congress has left alone for over 150 years. Not because the Constitution demands it, and not because nothing has tried to move it. Because every serious attempt since 1869 has run into enough resistance to stop.