What is the purpose of the judicial branch?

The purpose of the judicial branch is to interpret federal laws, apply them to specific cases and controversies, and administer justice through fair and impartial proceedings. Article III of the Constitution creates one Supreme Court and authorizes Congress to establish inferior federal courts, which now include 13 courts of appeals and 94 federal district courts plus specialized courts like the United States Court of International Trade and the United States Tax Court. Federal judges nominated by the president and confirmed by the Senate hold office during good behavior, which functionally means for life unless they choose to retire, are impeached, or are convicted of crimes.

This life tenure was deliberate. Alexander Hamilton argued in Federalist No. 78 in 1788 that judges insulated from political pressure could enforce constitutional limits and protect individual rights against legislative or executive overreach.

Several specific functions follow from this purpose. Federal courts decide cases and controversies between parties, including civil disputes between citizens of different states, federal criminal prosecutions, suits arising under federal statutes or the Constitution, and disputes involving the United States or foreign citizens. They interpret what statutes mean when they are unclear, an essential function because legislative language can rarely anticipate every situation. They protect individual rights by ensuring that government action complies with the Bill of Rights, the Fourteenth Amendment, and other constitutional guarantees. They exercise judicial review, the power established in Marbury v. Madison in 1803, to strike down federal and state laws and executive actions that violate the Constitution. Federal courts also resolve disputes between states under Article III's grant of original Supreme Court jurisdiction.

The Supreme Court of the United States, the only federal court named in the Constitution, currently has nine justices. It hears about 60 to 80 cases per year out of more than 7,000 petitions for review, focusing on cases of national importance, conflicts among lower courts, or significant constitutional questions. Its rulings bind every other court and government official in the country.

Lower federal courts handle the vast majority of federal litigation, with cases progressing from district courts to courts of appeals before any possibility of Supreme Court review. The state court systems, separate from the federal courts, handle most criminal prosecutions, family law, property disputes, contracts, and other matters traditionally governed by state law.