LEGAL MISCONCEPTIONS: An Appellate Lawyer’s Perspective on Conversion Under Rule 12 (b)

Robert Mandel

By Robert A. Mandel

Robert A. Mandel is co-founder of Mandel Young plc (, a Phoenix-based appellate law firm. Known for his potent advocacy, Rob routinely appears in business, constitutional and public law disputes pending in the federal and state appellate courts, where he handles appeals of final judgments, preliminary injunctions and other interlocutory decrees, petitions for writs of certiorari (review) and mandamus (special actions), certified questions, motion practice, and the representation of amici curiae. Rob also is retained as appellate counselor-inresidence, working collaboratively with litigators to optimize their cases for trial and appeal and undertaking primary responsibility for critical projects, including dispositive motions.

As appellate lawyers, my partner and I are professional “issue spotters.” One hazard of our line of work is the tendency to obsess over certain legal misconceptions—particularly when they repeatedly raise their ugly heads in the trial courts. Although we’ve learned not to kvetch about this stuff at parties, we feel obliged to bring at least some attention to the most persistent errors we see. So, at the risk of firmly cementing our reputations as nerds, this month we tackle a procedural misconception that has serious consequences for the unwary—namely, the notion that a motion to dismiss presenting “matters outside the pleading” must be treated as a motion for summary judgment.

The Conversion Rule Applies to Motions to Dismiss under Rule 12(b) (6), But Not To Other Grounds for Dismissal.
Rule 12(b) explicitly limits the conversion rule to motions brought pursuant to subpart (6), i.e., “failure to state a claim upon which relief can be granted”:
If, on a motion asserting the defense numbered 6 to dismiss for failure of the pleading to state a claim upon which relief can be granted, matters outside the pleading are presented to and not excluded by the court, the motion shall be treated as one for summary judgment and disposed of as provided in Rule 56 ….[1]

The express reference to “defense numbered 6” makes it clear that the conversion rule was not intended to be applied expansively.

Too often, however, the conversion rule is invoked to defeat other Rule 12(b) motions, especially if they are joined with a motion to dismiss pursuant to “defense numbered 6.” This tactic can have significant adverse consequences for one who has advanced, for example, a jurisdictional challenge to the complaint. Treatment of the motion as one for summary judgment could result in the litigation of a case over which the trial court lacks jurisdiction. The careful practitioner in such a case should be prepared to rebut the conversion argument and brief the trial court on what may be relied upon to resolve disputed issues of jurisdictional fact and who is to decide that question.

The Trial Court Considers the Evidence Presented to Decide Whether There is a Disputed Issue of Jurisdictional Fact.
If a defendant proffers evidence in a Rule 12(b)(1) motion that refutes subject matter jurisdiction, the burden shifts to the plaintiff to show that jurisdiction is proper. To do so, the plaintiff must furnish affidavits or other evidence necessary to establish subject matter jurisdiction. The trial court must receive and consider such evidence to determine whether there is a genuinely disputed issue of jurisdictional fact to resolve.[2]

Given that it is the trial court’s obligation to receive and consider the evidence on the issue of jurisdiction, the mere fact that defendant presented evidence from outside the pleadings

“… It is also the court’s duty to resolve the issue and to do so before allowing the case to proceed any further.” cannot operate to convert a Rule 12(b)(1) motion into a Rule 56 motion for summary judgment. “Otherwise, the very existence of a factual dispute, which the court is empowered to resolve under Rule 12(b)(1), would, under the standards of Rule 56, require denial of the motion.”[3]

Disputed Issues of Jurisdictional Fact Are Usually Decided By the Trial Court.
Where a defendant’s Rule 12(b)(1) motion and the plaintiff’s response leads the trial court to conclude that such an issue exists, it is also the court’s duty to resolve the issue and to do so before allowing the case to proceed any further.[4] If the trial court cannot decide the issue based on the parties’ submissions and affidavits, it should conduct an evidentiary hearing to resolve jurisdictional questions.

There is, however, an important exception. A disputed issue of jurisdictional fact must go to the jury if the trial court finds that resolving it also necessarily decides the merits of the plaintiff’s cause of action.[5] In other words, if the trial court’s resolution of a disputed jurisdictional fact would negate a legal element of the plaintiff’s affirmative case, the court must defer in order to avoid impermissibly intruding on the province of the jury.

And there’s the rub. Even if a defendant spots the issue and convinces the court to consider matters outside the pleadings in a jurisdictional motion to dismiss, the case may need to proceed to trial despite that the court’s subject matter jurisdiction is doubtful.


[1] Even in the context of Rule 12(b)(6) dismissal motions, the courts have carved exceptions to the conversion rule.

[2] It follows that the opponent’s failure to present evidence of subject matter jurisdiction in his response to a Rule 12(b)(1) motion will often be fatal to his case.

[3] Gatecliff v. Great Republic Life Ins. Co., 154 Ariz. 502, 506, 744 P.2d 29, 33 (App. 1987) (quoting 2A Moore’s Federal Practice, § 12.07, at 12-48 (1984)).

[4] Morgan v. Hays, 102 Ariz. 150, 152-55, 426 P.2d 647, 649-52, cert. denied, 389 U.S. 859 (1967).

[5] Bonner v. Minico, Inc., 159 Ariz. 246, 253, 766 P.2d 598, 605 (1988).