How many justices are on the Supreme Court?

The Supreme Court has nine justices: one Chief Justice and eight Associate Justices. The number is set by federal law, not by the Constitution. The Constitution authorizes the Court but leaves the size to Congress. The Judiciary Act of 1789 originally set the size at six justices.

Congress changed the number several times during the 19th century, ranging from five during a brief period to ten during the Civil War. The current size of nine has held since 1869. President Franklin D. Roosevelt famously proposed expanding the Court to as many as 15 justices in 1937 after the Court struck down several New Deal programs. The plan, often called court-packing, met fierce resistance from both parties and was abandoned. Some justices on the Court began upholding New Deal legislation shortly after the proposal, in what some historians call the switch in time that saved nine.

The Chief Justice presides over the Court, leads its public sessions, sets the agenda for private conferences where justices discuss cases, and assigns who writes the majority opinion when the Chief Justice is in the majority. The Chief Justice also presides over presidential impeachment trials in the Senate (Article I, Section 3) and serves as chief administrative officer of the federal court system. The current Chief Justice is John Roberts, who was nominated by President George W. Bush and confirmed in 2005.

The eight Associate Justices have equal voting power with the Chief Justice on cases. Each justice has one vote. Decisions are made by majority vote, with the senior justice in the majority assigning who writes the opinion (or the Chief Justice doing so when in the majority). Justices write majority opinions, concurring opinions (agreeing with the result but for different reasons), and dissenting opinions.

The current justices are John Roberts (Chief Justice, appointed 2005), Clarence Thomas (1991), Samuel Alito (2006), Sonia Sotomayor (2009), Elena Kagan (2010), Neil Gorsuch (2017), Brett Kavanaugh (2018), Amy Coney Barrett (2020), and Ketanji Brown Jackson (2022). The longest-serving current justice is Clarence Thomas. The longest-serving justice in U.S. history was William O. Douglas, who served 36 years from 1939 to 1975.