Article III of the U.S. Constitution created a national Supreme Court and gave Congress the power to establish lower federal courts. Federal courts have jurisdiction (the authority to hear and decide a case) over eight kinds of cases. Most federal cases are held in one of the nation's 94 district courts. In these courts witnesses testify and juries hear cases and reach verdicts. A large percentage of people who lose their cases in district court appeal to the next highest level—a U.S. court of appeals. Appeals courts do not hold trials. A panel of judges reviews the case and listens to arguments from lawyers for each side. The judges may uphold the original decision, reverse that decision, or remand the case. If still dissatisfied with the decision, lawyers may appeal to the U.S. Supreme Court.

All federal judges, including Supreme Court justices, are appointed by the president and approved by the Senate. The First African American member of the Court was Thurgood Marshall. Sandra Day O'Connor was the first woman on the Court. One early chief justice, John Marshall, was a very influential member of the Court. His opinion in the case of Marbury v. Madison outlined one of the Court's most important powers—judicial review. With this power the Court can determine whether or not acts of Congress or executive order are constitutional.