Participation by a prosecutor is ordinarily necessary to assist the court in the presentation of a criminal contempt case. The procedural requirements of Rule 42(b) of the Federal Rules of Criminal Procedure, and those requirements such as trial by jury imposed judicially in light of due process considerations, give rise to the need for presentation of the evidence by an officer of the court appointed for prosecutive purposes. The United States Attorney naturally assumes the role of prosecutor when he initiates an application for a show cause order under Rule 42(b). However, in a number of circumstances involving the disobedience of judicial authority outside the presence of the court, contempt proceedings are initiated sua sponte by the court or by private litigants for whose benefit such orders have issued.
In the great majority of cases the dedication of the executive branch to the preservation of respect for judicial authority makes the acceptance by the United States Attorney of the court's request to prosecute a mere formality; however, there may be sound reasons in a given case for the United States Attorney to decline participation in the proceedings and for the prosecution to be conducted on behalf of the court by private counsel appointed by the court for this purpose. On a case-by-case basis, the United States Attorney should evaluate not only the propriety of his participation in 18 U.S.C. § 401 proceedings, but also the interest of the government as a litigant vis-a-vis the clear duty of the United States Attorney to preserve respect for the authority of the federal court upon which successful law enforcement relies.
[cited in Criminal Resource Manual 754; JM 9-39.000]