“Drawing the Line Between Fact and Law in Qualified-Immunity Appeals”
A Comprehensive Commentary on Horn v. Adger, 24-1034(L) (2d Cir. 2025)

1. Introduction

Parties and posture. In Horn v. Adger, two wrongfully-convicted men, Vernon Horn and Marquis Jackson (“Plaintiffs”), sued New Haven detectives and others under 42 U.S.C. § 1983 after their murder convictions were vacated in 2018. The detectives (“Detectives” or “Appellants”) moved for summary judgment on qualified-immunity grounds; the district court (Chatigny, J.) denied that motion. The Detectives filed an interlocutory appeal. Plaintiffs moved to dismiss for lack of appellate jurisdiction.

Key issues before the Second Circuit. The appeal asked whether: (i) qualified immunity could be reviewed immediately; (ii) the detectives’ alleged Brady violations, evidence fabrication, and failures to intervene were clearly established constitutional violations as a matter of law; and (iii) the detectives had properly preserved all immunity arguments.

The holding. In an unpublished “Summary Order,” the Second Circuit dismissed the appeal, reiterating that it lacks jurisdiction to review fact-dependent qualified-immunity denials and that undeveloped immunity arguments are waived. The court thus left the case for trial.

2. Summary of the Judgment

• Appellate jurisdiction. The collateral-order doctrine allows interlocutory review only of “purely legal” immunity questions. Resolving the detectives’ appeal would require factfinding (credibility of witnesses, truthfulness of statements, etc.), so jurisdiction was lacking.
• Brady claims. Because the plaintiffs presented evidence that exculpatory statements were suppressed and because the reliability of witnesses was central, the immunity question hinged on disputed facts. The detectives thus could not secure immediate review.
• Threat-suppression theory. The detectives never distinctly raised qualified immunity on the theory that they hid their own threats to witnesses. Under Second-Circuit precedent, a party waives immunity by failing to “adequately develop” the defense.
• Fabrication and failure-to-intervene. Again, material factual disputes barred appellate review: whether the detectives knowingly created false statements and whether they had opportunities to intervene are classic jury questions.
• Disposition. Plaintiffs’ motions to dismiss were granted; the appeal was dismissed.

3. Analysis

3.1 Precedents Cited and Their Influence

The panel leaned heavily on a line of Supreme Court and Second-Circuit cases demarcating the scope of interlocutory review.

• Mitchell v. Forsyth, 472 U.S. 511 (1985) – established that qualified-immunity denials may be immediately appealable, but only for pure questions of law.
• Walczyk v. Rio, 496 F.3d 139 (2d Cir. 2007) – reiterated that “purely legal” requirement.
• Salim v. Proulx, 93 F.3d 86 (2d Cir. 1996) and Doninger v. Niehoff, 642 F.3d 334 (2d Cir. 2011) – clarified that defendants cannot ask the appellate court to re-weigh evidence.
• Walker v. City of New York, 974 F.2d 293 (2d Cir. 1992) & Giglio/ Brady line – provided the clearly established duty to disclose exculpatory/impeachment evidence to prosecutors.
• Blissett v. Coughlin, 66 F.3d 531 (2d Cir. 1995) & McCardle v. Haddad, 131 F.3d 43 (2d Cir. 1997) – held that insufficiently articulated immunity defenses are waived.

Collectively, these authorities foreclosed the detectives’ attempt to secure appellate review on a record riddled with factual disputes and undeveloped arguments.

3.2 Legal Reasoning of the Court

1. The jurisdictional gate-keeping function. The panel applied a two-step filter: (a) Are we being asked only to decide a point of law? (b) Could we resolve immunity without crediting either side’s disputed version of events? If the answer to either was “no,” the court lacked jurisdiction. That test ended the appeal.
2. Fact/law distinction. The panel emphasized the “fact/law divide”: deciding whether exculpatory statements were suppressed, whether threats were made, or whether detectives fabricated evidence—all require credibility determinations reserved for a jury.
3. Waiver doctrine. Because the detectives’ summary-judgment papers lumped “threat suppression” into a general “no Brady duty” argument, they failed to “adequately develop” a distinct immunity defense. Under Blissett, the defense was forfeited.
4. Qualified-immunity timing. The court noted that immunity can still be raised at trial or after a verdict, preserving the balance between protecting officials and vindicating constitutional rights.

3.3 Potential Impact on Future Litigation

• Sharper briefing requirements. Defense counsel must isolate each theory of liability and “pin” a discrete qualified-immunity argument to it, or risk waiver.
• Limited interlocutory appeals. Litigants are reminded that evidence-sufficiency disputes—common in § 1983 actions—are rarely appealable mid-case.
• Brady litigation. The order re-affirms that police suppression of impeachment evidence and witness-coercion details has long been “clearly established,” making immunity an uphill climb.
• Strategic trial planning. Plaintiffs gain leverage: the case proceeds to discovery and trial, increasing settlement pressure on municipalities and individual officers.
• Judicial efficiency. By policing the factual/legal boundary, the Second Circuit limits piecemeal appeals, conserving appellate resources.

4. Complex Concepts Simplified

• Qualified Immunity (QI). A defense shielding officials from personal liability unless they violated a “clearly established” right that any reasonable officer would have known.
• Collateral Order Doctrine. A narrow exception letting some non-final orders be appealed immediately; applies to QI denials only for pure legal questions.
• Brady Material. Evidence favorable to the accused—either exculpatory or impeaching—that the prosecution must disclose.
• Fabrication of Evidence. When an officer knowingly creates false information likely to influence a jury and forwards it to prosecutors, it violates due-process rights.
• Failure to Intervene. An officer present at a constitutional violation who has a realistic chance to stop it but doesn’t can be liable.
• Waiver of QI. If a defendant does not specifically and timely raise or develop the qualified-immunity defense for a claim, the court can deem it forfeited.

5. Conclusion

Horn v. Adger does not break new substantive ground on Brady or fabrication law; its importance lies in procedure. The Second Circuit:

• Re-clarified that interlocutory review of qualified-immunity denials is confined to purely legal issues; facts belong to the jury.
• Confirmed that poorly articulated immunity arguments can be—and here were—waived.
• Strengthened the message that officers cannot avoid trial by challenging evidence sufficiency on appeal.

Practitioners should treat the opinion as a cautionary tale: marshal undisputed facts, frame strictly legal questions, and develop each immunity theory with precision, or expect dismissal at the appellate threshold.

Substantively, the order underscores the enduring force of Brady, Giglio, and Ricciuti: officers who hide exculpatory or impeachment evidence, or who manufacture facts, tread on clearly established territory and may face liability. Procedurally, it cements the Second Circuit’s commitment to policing the fact-law boundary in qualified-immunity appeals, ensuring that juries, not appellate panels, decide disputed historical facts.