Rule 21. Writs of Mandamus and Prohibition, and Other Extraordinary Writs

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(a) Mandamus or Prohibition to a Court: Petition, Filing, Service, and Docketing.

(1) A party petitioning for a writ of mandamus or prohibition directed to a court must file a petition with the circuit clerk and serve it on all parties to the proceeding in the trial court. The party must also provide a copy to the trial-court judge. All parties to the proceeding in the trial court other than the petitioner are respondents for all purposes.

(2)(A) The petition must be titled “In re [name of petitioner].”

(B) The petition must state:

(i) the relief sought;

(ii) the issues presented;

(iii) the facts necessary to understand the issue presented by the petition; and

(iv) the reasons why the writ should issue.

(C) The petition must include a copy of any order or opinion or parts of the record that may be essential to understand the matters set forth in the petition.

(3) Upon receiving the prescribed docket fee, the clerk must docket the petition and submit it to the court.

(b) Denial; Order Directing Answer; Briefs; Precedence.

(1) The court may deny the petition without an answer. Otherwise, it must order the respondent, if any, to answer within a fixed time.

(2) The clerk must serve the order to respond on all persons directed to respond.

(3) Two or more respondents may answer jointly.

(4) The court of appeals may invite or order the trial-court judge to address the petition or may invite an amicus curiae to do so. The trial-court judge may request permission to address the petition but may not do so unless invited or ordered to do so by the court of appeals.

(5) If briefing or oral argument is required, the clerk must advise the parties, and when appropriate, the trial-court judge or amicus curiae.

(6) The proceeding must be given preference over ordinary civil cases.

(7) The circuit clerk must send a copy of the final disposition to the trial-court judge.

(c) Other Extraordinary Writs. An application for an extraordinary writ other than one provided for in Rule 21(a) must be made by filing a petition with the circuit clerk and serving it on the respondents. Proceedings on the application must conform, so far as is practicable, to the procedures prescribed in Rule 21(a) and (b).

(d) Form of Papers; Number of Copies; Length Limits. All papers must conform to Rule 32(c)(2). An original and 3 copies must be filed unless the court requires the filing of a different number by local rule or by order in a particular case. Except by the court’s permission, and excluding the accompanying documents required by Rule 21(a)(2)(C):

(1) a paper produced using a computer must not exceed 7,800 words; and

(2) a handwritten or typewritten paper must not exceed 30 pages.


(As amended Apr. 29, 1994, eff. Dec. 1, 1994; Apr. 23, 1996, eff. Dec. 1, 1996; Apr. 24, 1998, eff. Dec. 1, 1998; Apr. 29, 2002, eff. Dec. 1, 2002; Apr. 28, 2016, eff. Dec 1, 2016; Apr. 25, 2019, eff. Dec. 1, 2019.)

Notes of Advisory Committee on Rules—1967

The authority of courts of appeals to issue extraordinary writs is derived from 28 U.S.C. §1651. Subdivisions (a) and (b) regulate in detail the procedure surrounding the writs most commonly sought—mandamus or prohibition directed to a judge or judges. Those subdivisions are based upon Supreme Court Rule 31, with certain changes which reflect the uniform practice among the circuits (Seventh Circuit Rule 19 is a typical circuit rule). Subdivision (c) sets out a very general procedure to be followed in applications for the variety of other writs which may be issued under the authority of 28 U.S.C. §1651.

Notes of Advisory Committee on Rules—1994 Amendment

Subdivision (d). The amendment makes it clear that a court may require a different number of copies either by rule or by order in an individual case. The number of copies of any document that a court of appeals needs varies depending upon the way in which the court conducts business. The internal operation of the courts of appeals necessarily varies from circuit to circuit because of differences in the number of judges, the geographic area included within the circuit, and other such factors. Uniformity could be achieved only by setting the number of copies artificially high so that parties in all circuits file enough copies to satisfy the needs of the court requiring the greatest number. Rather than do that, the Committee decided to make it clear that local rules may require a greater or lesser number of copies and that, if the circumstances of a particular case indicate the need for a different number of copies in that case, the court may so order.

Notes of Advisory Committee on Rules—1996 Amendment

In most instances, a writ of mandamus or prohibition is not actually directed to a judge in any more personal way than is an order reversing a court's judgment. Most often a petition for a writ of mandamus seeks review of the intrinsic merits of a judge's action and is in reality an adversary proceeding between the parties. See, e.g., Walker v. Columbia Broadcasting System, Inc., 443 F.2d 33 (7th Cir. 1971). In order to change the tone of the rule and of mandamus proceedings generally, the rule is amended so that the judge is not treated as a respondent. The caption and subdivision (a) are amended by deleting the reference to the writs as being “directed to a judge or judges.”

Subdivision (a). Subdivision (a) applies to writs of mandamus or prohibition directed to a court, but it is amended so that a petition for a writ of mandamus or prohibition does not bear the name of the judge. The amendments to subdivision (a) speak, however, about mandamus or prohibition “directed to a court.” This language is inserted to distinguish subdivision (a) from subdivision (c). Subdivision (c) governs all other extraordinary writs, including a writ of mandamus or prohibition directed to an administrative agency rather than to a court and a writ of habeas corpus.

The amendments require the petitioner to provide a copy of the petition to the trial court judge. This will alert the judge to the filing of the petition. This is necessary because the trial court judge is not treated as a respondent and, as a result, is not served. A companion amendment is made in subdivision (b). It requires the circuit clerk to send a copy of the disposition of the petition to the trial court judge.

Subdivision (b). The amendment provides that even if relief is requested of a particular judge, although the judge may request permission to respond, the judge may not do so unless the court invites or orders a response.

The court of appeals ordinarily will be adequately informed not only by the opinions or statements made by the trial court judge contemporaneously with the entry of the challenged order but also by the arguments made on behalf of the party opposing the relief. The latter does not create an attorney-client relationship between the party's attorney and the judge whose action is challenged, nor does it give rise to any right to compensation from the judge.

If the court of appeals desires to hear from the trial court judge, however, the court may invite or order the judge to respond. In some instances, especially those involving court administration or the failure of a judge to act, it may be that no one other than the judge can provide a thorough explanation of the matters at issue. Because it is ordinarily undesirable to place the trial court judge, even temporarily, in an adversarial posture with a litigant, the rule permits a court of appeals to invite an amicus curiae to provide a response to the petition. In those instances in which the respondent does not oppose issuance of the writ or does not have sufficient perspective on the issue to provide an adequate response, participation of an amicus may avoid the need for the trial judge to participate.

Subdivision (c). The changes are stylistic only. No substantive changes are intended.

Committee Notes on Rules—1998 Amendment

The language and organization of the rule are amended to make the rule more easily understood. In addition to changes made to improve the understanding, the Advisory Committee has changed language to make style and terminology consistent throughout the appellate rules. These changes are intended to be stylistic only.

Committee Notes on Rules—2002 Amendment

Subdivision (d). A petition for a writ of mandamus or prohibition, an application for another extraordinary writ, and an answer to such a petition or application are all “other papers” for purposes of Rule 32(c)(2), and all of the requirements of Rule 32(a) apply to those papers, except as provided in Rule 32(c)(2). During the 1998 restyling of the Federal Rules of Appellate Procedure, Rule 21(d) was inadvertently changed to suggest that only the requirements of Rule 32(a)(1) apply to such papers. Rule 21(d) has been amended to correct that error.

Rule 21(d) has been further amended to limit the length of papers filed under Rule 21.

Changes Made After Publication and Comments. No changes were made to the text of the proposed amendment or to the Committee Note, except that the page limit was increased from 20 pages to 30 pages. The Committee was persuaded by some commentators that petitions for extraordinary writs closely resemble principal briefs on the merits and should be allotted more than 20 pages.

Committee Notes on Rules—2016 Amendment

The page limits previously employed in Rules 5, 21, 27, 35, and 40 have been largely overtaken by changes in technology. For papers produced using a computer, those page limits are now replaced by word limits. The word limits were derived from the current page limits using the assumption that one page is equivalent to 260 words. Papers produced using a computer must include the certificate of compliance required by Rule 32(g); Form 6 in the Appendix of Forms suffices to meet that requirement. Page limits are retained for papers prepared without the aid of a computer (i.e., handwritten or typewritten papers). For both the word limit and the page limit, the calculation excludes the accompanying documents required by Rule 21(a)(2)(C) and any items listed in Rule 32(f).

Committee Notes on Rules—2019 Amendment

The term "proof of service" in subdivisions (a)(1) and (c) is deleted to reflect amendments to Rule 25(d) that eliminate the requirement of a proof of service when service is completed using a court's electronic filing system.