A United States Magistrate Judge is a judicial officer who serves the United States District Court pursuant to a statutory appointment process rather than the presidential nomination and senate confirmation process used to appoint District Judges under Article III of the Constitution. When you file a civil case, your case will be assigned to both a district judge and a magistrate judge.  

The duties and authorities of a United States Magistrate Judge are outlined in 28 U.S.C. § 636.