How many justices are on the Supreme Court?

Why this is the answer

USCIS does not print a number for this question in its 2008 test materials. It points applicants to its test updates page instead, because answers like this one can change through appointments, and the officer will not accept an answer that is wrong on the day of the interview. Check the figure shortly before you go and give the number as it stands then. The Constitution offers no shortcut here. Article III creates "one supreme Court" and lets Congress set up lower courts, but it never says how many justices sit on the Supreme Court. The text says far more about how judges serve than about how many there are: they hold office "during good Behaviour," and their pay cannot be cut while they serve. Hamilton explained the purpose of that tenure in Federalist No. 78. He called the judiciary the least dangerous branch, holding neither the sword nor the purse, only judgment, and argued that because the courts were to guard a limited Constitution against overreach by the legislature, judges needed permanent tenure to give them an independent spirit. What the justices do with that independence is the part worth learning well. Anyone who believes a law does not follow the Constitution can bring a case to federal court. Once the Supreme Court decides a case, no other court in the country can change the decision. The Court can also find that a state law or action conflicts with federal law or with the Constitution, which makes that state law invalid; Marbury v. Madison established this power, known as judicial review. Its rulings can reshape everyday life, as Brown v. the Board of Education of Topeka did when it ended racial segregation in schools. Inside the Court, the justices meet to discuss each case and vote on it, and a majority means more than half of the justices voting the same way. The Chief Justice leads those discussions, yet every justice makes his or her own decision. Don't answer this question with a name. It asks for a count; the next question, about the Chief Justice, is the one that wants a person.