Mootness Risk Is Only a Factor in Rule 54(b) Certification; Monell Liability Requires Specific, Similar Patterns and Causation

1. Introduction

Aaron Davis v. Tyler W.A. Duncan (6th Cir. Aug. 13, 2026) arises from an undisputed assault by corrections officer Tyler Duncan against inmate Aaron Davis at the Multi-County Correctional Center (“MCCC”). Davis sued under 42 U.S.C. § 1983, asserting: (i) claims against Duncan for Fourth Amendment violations; (ii) claims against MCCC’s Executive Director Dale Osborn for supervisory liability (and an unappealed failure-to-protect theory); and (iii) Monell municipal-liability claims against Marion County, Hardin County, and the Marion-Hardin Correction Commission (“MHCC”) for failure to train, a custom of acquiescence, and negligent hiring.

The district court granted summary judgment to all defendants except Duncan and certified the partial judgment for immediate appeal under Federal Rule of Civil Procedure 54(b). The Sixth Circuit affirmed, holding (a) the Rule 54(b) certification was within the district court’s discretion, and (b) Davis failed to create triable issues on his Monell and supervisory-liability theories against the appealed defendants. Judge Bush dissented on jurisdiction, arguing the appeal should be dismissed because a trial outcome against Duncan could moot the issues on appeal.

2. Summary of the Opinion

  • Appellate jurisdiction: The panel majority held Rule 54(b) certification was proper and entitled to “substantial deference” (citing Solomon v. Aetna Life Ins. Co.), rejecting the dissent’s view that the mere possibility of mootness categorically bars certification.
  • Failure-to-train (Monell): Davis did not show deliberate indifference under City of Canton v. Harris and Bd. of Comm’rs v. Brown, and also failed causation because Duncan testified he knew he was not permitted to enter Davis’s cell under the circumstances.
  • Custom of acquiescence (Monell): Davis failed to establish a “clear and persistent pattern” of sufficiently similar unconstitutional conduct as required by Franklin v. Franklin County; many examples were not raised below and, even considered, were not comparable to the alleged constitutional violation.
  • Negligent hiring (Monell): Under Brown, Davis did not show Duncan was “highly likely” to inflict the “particular injury” suffered, nor a “strong” connection between pre-hire background and the specific violation.
  • Supervisory liability (Osborn): Davis did not produce evidence that Osborn “implicitly authorized, approved or knowingly acquiesced” in Duncan’s assault under Garza v. Lansing Sch. Dist. and Bellamy v. Bradley.
  • Disposition: The Sixth Circuit AFFIRMED summary judgment for the Institutional Defendants and Osborn.

3. Analysis

3.1. Precedents Cited (and How They Shaped the Decision)

A. Rule 54(b) certification and appellate jurisdiction

  • Planned Parenthood Sw. Ohio Region v. DeWine and Gen. Acquisition, Inc. v. GenCorp, Inc.: The majority used these decisions for the two-part Rule 54(b) framework—(1) final judgment as to fewer than all claims/parties and (2) “no just reason for delay”—and for the “nonexhaustive list of factors,” including the relationship between adjudicated and unadjudicated claims and the possibility of mootness.
  • Gavitt v. Born: Supplies the standards of review (de novo for the “final judgment” component and abuse of discretion for “no just reason for delay”). It also supports the dissent’s point that appellate courts must independently assure themselves of proper certification, even if not challenged.
  • Solomon v. Aetna Life Ins. Co.: The majority emphasized substantial deference to the district court’s certification decision.
  • Soliday v. Miami County and Corrosioneering, Inc. v. Thyssen Env’t Sys., Inc. (dissent): Judge Bush read these as establishing a near bright-line rule: certification is an abuse of discretion when remaining proceedings could moot the appeal. The majority resisted that characterization, treating mootness as one factor under Gen. Acquisition, not as an absolute bar.
  • In re Fifth Third Early Access Cash Advance Litig., Curtiss-Wright Corp. v. Gen. Elec. Co., Sherrod v. Wal-Mart Stores, Inc. (dissent): Cited to reinforce the separateness of the two Rule 54(b) prongs and the requirement of independent appellate review for abuse of discretion.
  • Carpenter v. Liberty Ins. Corp. and Wullschleger v. Royal Canin U.S.A., Inc. (dissent): Invoked to argue policy convenience cannot override jurisdictional limits.

B. Summary judgment methodology and record-citation discipline

  • Alford v. Deffendoll, Petsche v. Hruby, and Kirilenko-Ison v. Bd. of Educ. Of Danville Indep. Schs.: The majority applied the standard summary-judgment lens: de novo review, genuine disputes of material fact, and viewing evidence/inferences for the nonmovant.
  • Tolan v. Cotton: Davis argued the district court violated Tolan by resolving facts in defendants’ favor. The majority rejected this, distinguishing between (i) the absence of contradictory testimony on Duncan’s intent in the “Jones cell-entry incident” and (ii) Davis’s inability to supply record-cited evidence of “toxic culture.”
  • Franklin v. Franklin County and Anderson v. Liberty Lobby, Inc.: Used to underscore the nonmovant’s burden to “set forth specific facts” showing a genuine issue for trial.
  • Reed v. City of Memphis and Guarino v. Brookfield Twp. Tr.: The court stressed that district courts need not “comb the record sua sponte,” and appellate courts generally do not consider arguments newly advanced on appeal.

C. Municipal liability under § 1983 (Monell)

  • Burgess v. Fischer and Thomas v. City of Chattanooga: The court reiterated that municipal liability requires a policy/custom causing the federal violation and listed four recognized avenues. It also rejected Davis’s attempt to reframe Thomas as permitting a “totality” approach without “several separate instances.”
  • Ouza v. City of Dearborn Heights, Ellis v. Cleveland Mun. Sch. Dist., and Cherrington v. Skeeter: These supplied the three elements for failure-to-train and the “repeated complaints” route to deliberate indifference.
  • City of Canton v. Harris and Bd. of Comm’rs v. Brown: The majority relied on the “narrow range of circumstances” single-incident theory and the “obvious need” requirement; it also relied on Brown for the “moving force” causation and for the stringent negligent-hiring standard.
  • Alman v. Reed: Cited for the “moving force” language in the causation analysis of the failure-to-train claim.
  • Franklin v. Franklin County, Winkler v. Madison County, and Peet v. City of Detroit: These shaped the custom-of-acquiescence elements and the insistence on multiple, sufficiently similar prior incidents (a single incident is insufficient; even three discrete incidents may be insufficient depending on similarity and context).
  • Poynter v. Bennett and Poynter v. Bennett, 169 F.4th 716 (6th Cir. 2026) (order): The panel noted Davis’s reliance on Poynter was unavailing because the decision was vacated upon rehearing en banc.

D. Supervisory liability (individual-capacity § 1983)

  • Venema v. West and Peatross v. City of Memphis: Reaffirmed that supervisors are not liable under respondeat superior merely for oversight.
  • Garza v. Lansing Sch. Dist. and Bellamy v. Bradley: Supplied the controlling standard—implicit authorization/approval/knowing acquiescence—and explained that liability can arise through job-function omissions (e.g., failing to take precautions against likely violations).

E. Underlying constitutional violation and guilty plea (jurisdictional dissent)

  • Martinez v. Wayne County and McQueen v. Beecher Cmty. Schs. (dissent): Used for the proposition that Monell and supervisory-liability claims require an underlying constitutional violation.
  • State ex rel. Welsh Enters., Inc. v. Indus. Comm’n, Clark v. Irvin, and Marrese v. Am. Acad. of Orthopaedic Surgeons (dissent): Offered to argue Duncan’s Ohio guilty plea lacks preclusive effect under Ohio law (and that state preclusion rules govern).
  • State v. Peters, Wilkins v. Gaddy, and Hudson v. McMillian (dissent): Cited to argue Ohio felonious assault elements may not map onto the federal excessive-force standard (“maliciously and sadistically to cause harm”), so Duncan could theoretically prevail at trial, mooting the appeal.

3.2. Legal Reasoning

A. The majority’s Rule 54(b) principle: mootness risk is not dispositive

The most practically significant doctrinal move in the majority opinion is jurisdictional: it treats the “possibility of mootness” as a factor within a multi-factor, totality-of-circumstances inquiry under Gen. Acquisition, Inc. v. GenCorp, Inc., not as an automatic bar to certification. The majority also emphasizes deference to the district court’s case-management judgment (Solomon v. Aetna Life Ins. Co.) and credits the district court’s view that the appealed questions (institutional policy/custom) are analytically distinct from Duncan’s individual liability.

Judge Bush’s dissent frames Sixth Circuit precedent as stricter: if a remaining trial could moot the appeal, certification is an abuse of discretion (Soliday v. Miami County; Corrosioneering, Inc. v. Thyssen Env’t Sys., Inc.). He also highlights a concrete mooting path: if Duncan is found not to have committed an underlying constitutional violation, the Monell and supervisory-liability claims fail as a matter of law.

The split is less about the abstract Rule 54(b) standard and more about how strongly mootness potential constrains district-court discretion. The majority declines to adopt a categorical rule and finds no abuse of discretion on this record.

B. Failure to train: deliberate indifference and causation both fail

Applying Ouza v. City of Dearborn Heights, the majority held Davis failed on the second and third elements. Even accepting criticism of MCCC’s onboarding (self-taught course, open-book exam), the evidence showed MCCC’s training materials instructed de-escalation and prohibited excessive force, and Duncan acknowledged he knew he was not allowed to enter Davis’s cell.

That admission was decisive on causation: if the officer knew the rule and violated it anyway, the training program’s alleged inadequacy is not the “moving force” behind the injury (citing Alman v. Reed and Bd. of Comm’rs v. Brown). This reflects a recurring Sixth Circuit approach: single-incident failure-to-train claims are difficult where the plaintiff cannot show a gap in training that plausibly explains the officer’s conduct, as opposed to intentional misconduct despite training.

C. Custom of acquiescence: similarity, persistence, and preservation matter

The court applied the four-part test stated in Franklin v. Franklin County, with special emphasis on element (1)—a “clear and persistent pattern” of similar unconstitutional conduct. The majority found Davis’s examples deficient in three ways:

  1. Procedural preservation: key incidents were not identified in the district court briefing, and the Sixth Circuit generally will not consider newly presented arguments on appeal (Reed v. City of Memphis).
  2. Similarity: several incidents were not use-of-force incidents against inmates, or were materially different in purpose/context (e.g., attempts to revive a suicidal inmate).
  3. Quantity and specificity: at most, Davis identified only one other specific use-of-force incident besides his own, which did not satisfy the “clear and persistent” threshold (with Winkler v. Madison County and Peet v. City of Detroit illustrating the Sixth Circuit’s skepticism toward sparse incident showings).

The opinion also reinforces that generalized testimony about a “toxic culture,” without record-cited, discrete examples tied to the same right and the same kind of violation, will not survive summary judgment—especially where the nonmovant fails to do the citation work required by Anderson v. Liberty Lobby, Inc. and Franklin v. Franklin County.

D. Negligent hiring: Brown demands a strong, particularized connection

The majority corrected Davis’s framing of the standard and relied on Bd. of Comm’rs v. Brown to emphasize that municipal culpability cannot rest on general “bad background” inferences; the applicant must be “highly likely” to inflict the “particular injury,” and the connection between background and the specific constitutional violation must be “strong.”

Two of Davis’s proffered “trajectory” data points occurred after hiring (and thus cannot prove negligent hiring). The remaining pre-hire information—(i) a single juvenile-facility force write-up in a materially different scenario and (ii) termination from another facility based on suspected drug smuggling—did not show a strong, specific nexus to an unprovoked cell-entry assault on an inmate at MCCC.

E. Supervisory liability: delegation and post-incident response undermined “knowing acquiescence”

Under Garza v. Lansing Sch. Dist., the touchstone is the supervisor’s own unconstitutional conduct through authorization, approval, or knowing acquiescence. The majority found no triable evidence that Osborn knowingly tolerated a pattern of force, blocked information to remain ignorant, or participated in a cover-up. Instead, training was delegated to a captain, a prompt investigation followed, and Duncan was criminally charged and convicted—facts the panel treated as inconsistent with tacit approval.

3.3. Impact

  • Rule 54(b) practice in the Sixth Circuit: Although unpublished, the opinion supplies persuasive support for district courts treating mootness risk as one factor, not a categorical bar, when certifying partial judgments—particularly where the appealed issues are institutional (policy/custom) and the remaining issues are individual-liability trials. The dissent signals a continuing intra-circuit tension, and future litigants may cite it to challenge certifications where an underlying-violation trial could moot Monell appeals.
  • Evidence discipline at summary judgment: The case is a cautionary template: broad “culture” narratives must be tethered to record citations and preserved in the district court. Plaintiffs should expect that new incident examples raised for the first time on appeal will be discounted under Reed v. City of Memphis.
  • Monell theory selection: The decision underscores that “single-incident” failure-to-train claims remain narrow (City of Canton v. Harris) and that custom-of-acquiescence claims require both similarity and persistence (Franklin v. Franklin County).
  • Negligent hiring is especially demanding: Plaintiffs must connect pre-hire facts to the same kind of constitutional harm, not merely show a generalized risk (Brown).

4. Complex Concepts Simplified

  • Rule 54(b) certification: A mechanism allowing an immediate appeal of a final decision resolving some (but not all) claims/parties. The district court must find “no just reason for delay.” The majority treated possible mootness as a consideration; the dissent treated it as disqualifying in this context.
  • Monell liability: Municipal entities are not automatically liable for employees’ misconduct. The plaintiff must show a policy or custom caused the constitutional injury.
  • Failure to train (deliberate indifference): Not “training could be better,” but “the need for more/different training was obvious and ignoring it was deliberately indifferent,” and the training gap must actually cause the injury (City of Canton v. Harris; Ouza v. City of Dearborn Heights).
  • Custom of acquiescence: A pattern of similar unconstitutional acts, notice to the municipality, tacit approval through inaction, and causation (Franklin v. Franklin County).
  • Supervisory liability: Supervisors are not liable just because they supervise. Liability requires proof the supervisor authorized, approved, or knowingly tolerated the conduct (Garza v. Lansing Sch. Dist.).

5. Conclusion

The Sixth Circuit’s decision affirms summary judgment for the institutional and supervisory defendants in a jail-assault case, primarily because the plaintiff did not produce properly preserved, record-cited evidence establishing (i) deliberate indifference and causation for failure-to-train, (ii) a clear and persistent pattern of similar unconstitutional conduct for a custom-of-acquiescence theory, (iii) a strong, particularized nexus between pre-hire background and the specific harm for negligent hiring, or (iv) knowing acquiescence by the supervisor. On jurisdiction, the majority’s key takeaway is procedural: the possibility that later proceedings might moot the appeal does not automatically defeat Rule 54(b) certification; it is a factor reviewed deferentially for abuse of discretion, a position sharply contested by the dissent.