The procedural rulebook for asking a federal court of appeals to issue a writ of mandamus against a district court.

Federal Rule of Appellate Procedure 21 governs the mechanics of filing a mandamus petition directly with a U.S. court of appeals, most often to challenge a district court's action or inaction in an ongoing case.

Required contents of the petition

Rule 21 requires the petition to name every party as either petitioner or respondent, identify the district judge as a respondent (though the judge is typically not required to personally respond), and attach copies of any orders or opinions relevant to the dispute. The petition must clearly state the relief sought and the reasons the petitioner believes entitlement to that relief is clear.

The real party in interest

Because the petition targets a judge's action, the opposing party in the underlying district court case is treated as the "real party in interest" and is served with the petition, giving that party the opportunity to respond even though the judge is nominally the respondent.

Timeline and response process

The court of appeals may deny the petition outright, may order the real party in interest to respond within a set time, or may request a response from the district judge. If the court is inclined to grant relief without further briefing, it generally still gives the real party in interest an opportunity to respond first.

Why Rule 21 petitions are difficult to win

Appellate courts view mandamus against a fellow judge as an intrusion on the normal appellate process and reserve it for situations where a district court has clearly and indisputably exceeded its authority, and where no other adequate means exist to obtain relief, such as waiting for a final judgment and appealing in the ordinary course.