Horocofsky v. City of Lawrence (10th Cir. 2026): Police-Affidavit Causation Limits § 1983 Malicious Prosecution and Reasserts the Default Rule Against Retaining Supplemental State Claims After Federal Claims End

1. Introduction

In Horocofsky v. City of Lawrence, Kansas (10th Cir. July 24, 2026), the Tenth Circuit addressed a civil-rights suit arising from a law student’s rape report that resulted not in prosecution of the alleged assailant, but in prosecution of the reporter for false reporting. Plaintiff Bobbie Jo Horocofsky sued City of Lawrence police officers Charles Cottengim and Kimberlee Nicholson and the City, asserting federal claims (including malicious prosecution, conspiracy, and equal protection) and state-law tort claims.

The appeal presented a narrow set of issues: (i) dismissal on the pleadings of federal malicious-prosecution and conspiracy claims; (ii) denial of a late motion to amend to add a Fourth Amendment phone-search claim; (iii) summary judgment on an equal-protection claim; and (iv) summary judgment on state-law claims. The court largely affirmed but remanded for the district court to reconsider whether it should have retained supplemental jurisdiction over state claims after the federal claims were resolved.

2. Summary of the Opinion

  • § 1983 malicious prosecution (Rule 12(b)(6)): Dismissal affirmed because the complaint did not plausibly allege that officers caused the prosecution. The prosecution’s causal chain was not plausibly reconnected to the officers via a materially false or recklessly misleading probable-cause affidavit.
  • §§ 1983/1985(3) conspiracy (Rule 12(b)(6)): Dismissal affirmed because the complaint did not plausibly allege a “meeting of the minds” to violate rights—only, at most, joint participation in lawful investigative activity.
  • Late amendment (Rule 16(b)(4)): Denial affirmed; plaintiff failed to show “good cause” for moving months after she was on notice of the alleged overbroad phone download.
  • Equal protection (summary judgment): Affirmed; plaintiff failed to show a similarly situated comparator or circumstantial evidence sufficient to support an inference of gender discrimination.
  • State-law claims (summary judgment): Reversed and remanded; once federal claims ended before trial, the district court ordinarily “should” decline supplemental jurisdiction, and the record did not show the court considered that step after disposing of the last federal claim.

3. Analysis

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

Pleading standards; use of documents referenced in the complaint

  • Bledsoe v. Carreno and Ashcroft v. Iqbal supplied the two-step Rule 12(b)(6) approach: disregard conclusory assertions and then test whether well-pleaded facts plausibly support relief.
  • GFF Corp. v. Associated Wholesale Grocers, Inc. authorized consideration of an “indisputably authentic” document referenced by the complaint—here, the probable-cause affidavit—allowing the affidavit to control over inconsistent characterizations in the pleading.
  • Robbins v. Oklahoma reinforced individualized pleading in § 1983 cases (who did what to whom), undercutting plaintiff’s reliance on collective “Defendants” allegations, especially regarding alleged culture/behavior of unnamed officers.

§ 1983 malicious prosecution—causation through an affidavit

  • Coones v. Bd. of Cnty. Comm'rs of Unified Gov't of Wyandotte Cnty./Kan. City provided the elements, and the case turned on element (1): whether the defendants “caused” the prosecution.
  • Taylor v. Meacham and Albright v. Oliver framed the “anomalous” fit between “malicious prosecution” and police conduct because prosecutors and judges typically constitute intervening decisionmakers. Taylor also supplied the operative materiality test for affidavit inaccuracies: set aside falsehoods, include omissions, and reassess probable cause.
  • Pierce v. Gilchrist identified the path to causation despite intervening actors: an officer may “cause” prosecution if they knowingly/recklessly mislead via material falsehoods/omissions inducing the system to prosecute.
  • Kapinski v. City of Albuquerque informed the recklessness analysis; inclusion of some exculpatory facts can negate an inference that an omission was reckless.
  • Franks v. Delaware anchored the concept that “truthful” affidavits are those believed true by the affiant, not necessarily error-free, limiting plaintiff’s effort to recharacterize inferences as “false statements.”
  • United States v. Pulley (4th Cir.) was used for an important constraint: an affiant cannot intentionally or recklessly omit information they do not actually know; “should have known” is not enough for this theory.
  • Shrum v. Cooke was cited to confirm that the Taylor causation framework applies at the motion-to-dismiss stage, not only at summary judgment.
  • Becker v. Kroll supported waiver: plaintiff did not adequately develop alternative causation theories in her opening brief.

Conspiracy pleading under §§ 1983 and 1985(3)

  • Dixon v. City of Lawton framed § 1983 conspiracy as an agreement under color of law to deprive constitutional rights.
  • Brooks v. Gaenzle supplied the requirements for both § 1983 and § 1985(3) conspiracies: “meeting of the minds,” “agreement,” or a “general conspiratorial objective,” and (for § 1985(3)) a class-based animus requirement (which the panel did not need to reach). Torres v. Madrid was noted only as abrogating Brooks on other grounds.
  • Tonkovich v. Kan. Bd. of Regents and Bell Atl. Corp. v. Twombly drove the key pleading failure: conclusory conspiracy labels and “parallel conduct” do not plausibly show agreement.
  • Frasier v. Evans and Grider v. City of Auburn distinguished lawful agreement to investigate from unlawful agreement to violate rights; the complaint alleged, at most, coordinated investigation.

Late amendment—Rule 16 “good cause” and diligence

  • Gorsuch, Ltd., B.C. v. Wells Fargo Nat'l Bank Ass'n provided the two-step approach: after a scheduling deadline, the movant must satisfy Rule 16(b)(4) “good cause” before Rule 15(a) liberal amendment principles matter; lack of diligence defeats good cause.
  • Birch v. Polaris Indus., Inc. emphasized “notice” and the need to act promptly once aware an amendment may be required; the court analogized plaintiff’s months-long delay to the four-month delay rejected in Birch.
  • Husky Ventures, Inc. v. B55 Invs., Ltd. reinforced that diligence includes reasonably acquiring and acting upon information; “supposedly newly discovered” information does not excuse delay if diligence is lacking.
  • The panel also relied on the Fed. R. Civ. P. 16 advisory committee's note to 1983 amendment regarding subdiv. (b), item (4) on schedules being modifiable only when they cannot reasonably be met despite diligence.

Equal protection—comparators and circumstantial proof

  • Jones v. Norton supplied summary judgment standards (no genuine dispute of material fact).
  • Corder v. Lewis Palmer Sch. Dist. No. 38 stated the baseline principle: similarly situated persons should be treated alike.
  • Brown v. Montoya and Ashaheed v. Currington framed the comparator requirement: the plaintiff must show different treatment from persons “alike in all relevant respects,” and must identify concrete facts rather than conclusory claims.
  • Watson v. City of Kansas City established that although there is no general right to police protection, the state may not discriminate in providing it; the panel found plaintiff’s evidence insufficient to show discriminatory provision of protection.
  • Fowler v. Stitt was invoked for the proposition that discrimination may be shown by circumstantial evidence and the “totality of the relevant facts,” but the panel held plaintiff’s showing did not support a reasonable inference of gender bias.
  • Kendrick v. Penske Transp. Servs., Inc. was cited to acknowledge that direct evidence can suffice, but the panel held the direct-evidence theory was waived (not raised below or developed on appeal).

Supplemental jurisdiction—default rule after federal claims end pretrial

  • Barnett v. Hall, Estill, Hardwick, Gable, Golden & Nelson, P.C. and Brooks v. Gaenzle articulated the Supreme Court-encouraged practice: when federal claims drop out before trial, district courts ordinarily should dismiss or remand supplemental state claims absent compelling reasons to retain them.
  • Merrifield v. Bd. of Cnty. Comm'rs for Cnty. of Santa Fe and Ball v. Renner reinforced that general practice.

3.2. Legal Reasoning

(A) Malicious prosecution: “Causation” is not pleaded by attacking an affidavit with immaterial or unknown omissions

The panel treated the case as a classic Taylor/Pierce problem: a plaintiff may overcome intervening prosecutorial/judicial decisions only by plausibly alleging that an officer’s knowing or reckless affidavit falsehoods or omissions were material (i.e., vitiating probable cause) and thereby induced prosecution.

The court then narrowed plaintiff’s affidavit attacks into three categories:

  • Conclusory assertions (e.g., “full of gross omissions”) were ignored under Iqbal/Bledsoe.
  • Non-false or non-reckless “falsehoods”: Plaintiff challenged the inference drawn from correctly spelled text messages (arguing autocorrect). The court held that even if the inference was mistaken, the complaint did not plausibly allege Cottengim did not actually hold the belief he reported, invoking Franks’ understanding of affidavit “truthfulness.”
  • Omissions failed either because (i) the affidavit did not omit the point (it expressly referenced doctor advice and stress), (ii) the complaint did not allege the affiant actually knew the supposedly omitted facts (Pulley), or (iii) the missing information was immaterial because it would not change probable cause in light of what was already included.

In effect, the opinion strengthens a practical pleading filter: when the causation theory depends on affidavit manipulation, the complaint must connect specific, affiant-known, material inaccuracies to probable cause—otherwise intervening prosecutorial and judicial decisions break the chain.

(B) Conspiracy: joint investigation is not itself an unlawful agreement

For both § 1983 and § 1985(3), the court required plausible factual allegations of agreement—“meeting of the minds”—and rejected “parallel conduct” pleading under Twombly, consistent with Brooks and Tonkovich. Allegations that officers coordinated with a university investigator, exchanged information, or “worked closely” were categorized as lawful investigative cooperation under Frasier. Additionally, generalized allegations about other officers’ attitudes toward other complainants failed under Robbins because they did not specify what these named defendants did.

(C) Amendment after the deadline: “good cause” demands prompt action after notice

The court assumed plaintiff first learned, through a July 2023 deposition, of the alleged “comprehensive” phone download beyond limited consent, but still affirmed denial because plaintiff waited about five months to seek amendment. Under Gorsuch, Birch, and Husky Ventures, diligence is the core of “good cause.” The panel was unpersuaded by plaintiff’s explanation that she awaited expert work and a supplemental report, noting she did not explain why she could not plead the claim once on notice of the alleged overbreadth, or why additional months were needed thereafter.

(D) Equal protection: no “similarly situated” comparator and insufficient circumstantial inference

The panel applied comparator principles from Brown and Ashaheed and held plaintiff did not show she was similarly situated to the alleged assailant. The court highlighted “relevant respects” differences (different suspected offenses, who initiated police involvement, and alleged inconsistencies). Turning to circumstantial proof under Watson and Fowler, the court found the cited evidence (abrasive treatment of another complainant, “high-fives” by officers not including defendants, and the mere fact defendants credited one account over another) did not permit a reasonable inference of gender discrimination on this record.

(E) Supplemental jurisdiction: after the last federal claim ends pretrial, courts ordinarily should let state courts decide state claims

The most forward-looking procedural point is the remand: once the equal-protection claim fell at summary judgment, the case had no federal claims left “before trial.” Under 28 U.S.C. § 1367(c)(3) and Tenth Circuit guidance in Barnett, Brooks, Merrifield, and Ball, the district court ordinarily should decline supplemental jurisdiction absent compelling reasons. Because the record did not show the court revisited the supplemental-jurisdiction question at that juncture, the panel reversed the merits disposition of state-law claims and remanded for the district court to decide whether to retain them.

3.3. Impact

  • Higher pleading precision for affidavit-based malicious-prosecution causation: Plaintiffs who rely on an affidavit to connect police conduct to prosecution must plead (i) what was false/omitted, (ii) that the affiant actually knew the omitted facts (not merely “should have known”), (iii) recklessness/knowing falsity, and (iv) materiality under a corrected-affidavit probable-cause analysis.
  • Constraining “conspiracy” as a litigation add-on: The opinion continues a trend of treating conspiracy claims skeptically when they repackage investigative cooperation without concrete facts showing agreement to violate rights.
  • Rule 16 as a real gatekeeper: Even potentially significant constitutional claims (here, a phone-search claim) can be lost if not promptly sought once discovered; expert-driven refinement may not excuse months of delay absent a specific explanation tied to pleading necessity.
  • Equal-protection policing claims remain difficult without comparators or strong statistical/pattern evidence: The court signals that disbelief of a complainant, without more, does not itself permit an inference of sex discrimination.
  • Procedural corrective on supplemental jurisdiction: The remand underscores that district courts should explicitly re-evaluate § 1367(c) once federal claims are gone, even if they previously retained state claims while federal claims remained.

4. Complex Concepts Simplified

“Causation” in § 1983 malicious prosecution

Because prosecutors decide whether to charge and judges often find probable cause, police usually are not seen as the direct “cause” of a prosecution. The exception is when police mislead the system—typically through an affidavit—by knowingly or recklessly including material lies or leaving out material facts. If a corrected affidavit would still show probable cause, the officer’s affidavit does not “cause” the prosecution in the required sense.

“Materiality” (corrected-affidavit test)

Courts ask: if you remove the alleged false statements and add the alleged omitted facts, would probable cause still exist? If yes, the alleged errors are not “material,” and the claim fails on causation.

“Reckless disregard for the truth”

Recklessness is more than sloppiness. The plaintiff must plausibly show the officer seriously doubted the truth of what was submitted (or consciously disregarded a substantial risk of falsity). Simply alleging the officer should have investigated more typically sounds in negligence, not recklessness.

Conspiracy: “meeting of the minds”

A conspiracy claim requires facts showing an agreement to violate rights, not merely that parties communicated, worked together, or engaged in the same investigation. Parallel or coordinated lawful action does not, without more, imply unlawful agreement.

Rule 16 “good cause” for late amendments

After the court’s amendment deadline passes, the question is diligence: once you are on notice of facts supporting a new claim, you must move promptly. Waiting to perfect the claim with experts may be insufficient unless you explain why the claim could not reasonably be pleaded earlier.

Supplemental jurisdiction under 28 U.S.C. § 1367(c)(3)

Federal courts can hear state-law claims tied to federal claims. But when all federal claims are dismissed before trial, the usual practice is to let state courts decide the remaining state issues—unless there is a strong reason (e.g., exceptional judicial economy or fairness concerns) to keep the case in federal court.

5. Conclusion

Horocofsky reinforces several Tenth Circuit through-lines: (1) affidavit-based malicious-prosecution claims rise or fall on specifically pleaded, affiant-known, material misstatements or omissions; (2) conspiracy claims require concrete facts showing agreement to violate rights, not shared investigation; (3) Rule 16 diligence can be dispositive even for serious constitutional claims; and (4) when federal claims end before trial, district courts should ordinarily reconsider and usually decline supplemental jurisdiction over remaining state-law claims. The remand on the state claims serves as a procedural reminder that § 1367(c) is not a one-time decision but may require renewed attention as the federal case posture changes.