Article III of the Constitution guarantees that every person accused of wrongdoing has the right to a fair trial before a competent judge and a jury of one's peers. Where the executive and legislative branches are elected by the people, members of the Judicial Branch are appointed by the President and Confirmed by the Senate.
The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behaviour, and shall, at stated Times, receive for their Services, a Compensation, which shall not be diminished during their Continuance in Office.
Article III of the Constitution, which establishes the Judicial Branch, leaves Congress significant discretion to determine the shape and structure of the federal judiciary. Even the number of Supreme Court Justices is left to Congress — at times there have been as few as six, while the current number (nine, with one Chief Justice and eight Associate Justices) has only been in place since 1869. The Constitution also grants Congress the power to establish courts inferior to the Supreme Court, and to that end Congress has established the United States district courts, which try most federal cases, and 13 United States courts of appeals, which review appealed district court cases.
Federal courts enjoy the sole power to interpret the law, determine the constitutionality of the law, and apply it to individual cases. The courts, like Congress, can compel the production of evidence and testimony through the use of a subpoena. The inferior courts are constrained by the decisions of the Supreme Court — once the Supreme Court interprets a law, inferior courts must apply the Supreme Court’s interpretation to the facts of a particular case.
Learn more about the Judicial Branch.