Article III of the U.S. Constitution

Article III of the U.S. Constitution establishes the federal judicial branch including the U.S. Supreme Court, and the lower federal courts as established through Congressional legislation, namely, the federal Circuit Courts of Appeals and the federal District Courts. Judges appointed to serve on the federal courts pursuant to Article III are nominated by the President and confirmed by the U.S. Senate for lifetime tenure. They are sometimes referred to as "Article III judges."

Federal magistrate judges, in contrast, are judges appointed to assist U.S. district court judges in the performance of their duties, pursuant to 28 U.S.C. § 631. Magistrate judges are generally appointed by vote of the federal district judges of a particular court, serve terms of eight years (full-time) or four years (part-time), and may be re-appointed. Magistrate judges conduct a wide range of judicial proceedings, depending on the particular federal district court in which they sit.