The Constitution requires that a federal judge exercise the judicial power of the United States. According to Article III of the Constitution, a federal judge is to interpret the law free from the fear of loss of employment or diminished pay.
According to the U.S. Constitution, a federal judge is to be appointed by the President of the United States and approved by Congress. A federal judge's time in court continues for life, or during "good behavior" as written in Article III Section One of the Constitution. This means that, barring death, retirement or impeachment, a federal judge holds tenure at his position and can make legal decisions freely.
Although the Supreme Court is the only federal court explicitly established by the Constitution, it allowed for Congress to establish "inferior" courts to relieve the workload of the Supreme Court. Consequently, a federal judge can be not only one of nine Supreme Court justices but also one of the hundreds of appeal court and magistrate judges across the country. Besides defining the appointment and tenure of a federal judge, the Constitution gives little instruction regarding the qualifications or job description of a federal judge, although it is assumed that a judge has previously served as a lawyer or law professor.