No Clearly Established Bystander Liability for Backup Officers in DUI Arrests: Sixth Circuit Clarifies Prolonged-Stop, HGN, and Curtilage Rules

Introduction

In Amanda Caton v. Jacob Salamon, No. 24-3850 (6th Cir. Oct. 10, 2025) (not recommended for publication), the Sixth Circuit addressed a suite of Fourth Amendment and Ohio tort claims arising from a late-night OVI (operating a vehicle while intoxicated) stop and arrest in Loveland, Ohio. Plaintiffs Amanda and Patrick Caton—both Cincinnati police officers off duty at the time—alleged constitutional violations tied to the prolonging of a traffic stop, Amanda’s arrest based on a disputed horizontal gaze nystagmus (HGN) test and refusal to perform other field sobriety tests, and officers’ later entry onto the couple’s driveway. They also brought municipal failure-to-train claims and Ohio tort claims for false arrest/false imprisonment, malicious prosecution, and intrusion upon seclusion.

The panel affirmed in part, reversed in part, and vacated in part the district court’s mixed summary-judgment rulings on qualified immunity and state-law immunity. Most notably, the court:

• Allowed the prolonged-stop and wrongful-arrest claims to proceed against the arresting officer (Salamon) in light of disputed facts and clearly established law governing reasonable suspicion and probable cause in OVI stops.
• Granted qualified immunity to the backup officer (Parks), holding there was no clearly established law imposing bystander/supervisory liability on a backup officer in the DUI context based merely on his presence and failure to scrutinize another officer’s sobriety testing.
• Rejected the curtilage-based Fourth Amendment claim where officers briefly stepped onto the driveway and requested consent, reiterating that the Fourth Amendment protects against searches and seizures, not mere trespass-like presence absent investigative conduct.
• Allowed Ohio false arrest/false imprisonment and malicious prosecution claims against Salamon to proceed past statutory immunity based on record-supported allegations of bad faith; and vacated the intrusion-upon-seclusion ruling for the district court to address Ohio’s statutory immunity standard in the first instance.

Summary of the Opinion

• Prolonged stop: Affirmed denial of qualified immunity as to Officer Salamon. Under Rodriguez v. United States, prolonging a completed traffic stop requires reasonable suspicion; here, disputed facts left a jury question, and the governing law was clearly established by Green v. Throckmorton (6th Cir. 2012).
• Arrest/probable cause: Affirmed denial of qualified immunity as to Officer Salamon. Disputed HGN results and refusal to perform other sobriety tests, without corroborating indicia (odor, slurred speech, glassy eyes, unsteady gait), could not establish probable cause as a matter of clearly established law (Throckmorton; Miller v. Sanilac County; Kinlin v. Kline).
• Backup officer liability: Reversed denial of qualified immunity as to Officer Parks. The court found no clearly established precedent imposing supervisory/bystander liability on a backup officer in a drunk-driving arrest for merely arriving and not second-guessing another officer’s sobriety testing or arrest decision.
• Monell/failure-to-train: Exercised limited pendent jurisdiction under King v. City of Rockford (2024). Reversed municipal liability only insofar as it rested on Parks (no underlying constitutional violation). Left undisturbed the district court’s failure-to-train rulings tied to Salamon (beyond the court’s pendent jurisdiction at this stage).
• Curtilage claim: Reversed. Even assuming the driveway was curtilage, there was no search or seizure. Brief entry and a request for permission fall within the knock-and-talk doctrine (Jardines; Watson v. Pearson; Kentucky v. King; Widgren v. Maple Grove Township).
• Ohio torts: Affirmed denial of statutory immunity and summary judgment for Salamon on false arrest/false imprisonment and malicious prosecution (given lack of probable cause and allegations of bad faith). Vacated and remanded intrusion-upon-seclusion for the district court to apply Ohio Rev. Code § 2744.03(A)(6)(b)’s malice/bad-faith/wanton/reckless standard.

Analysis

Appellate Jurisdiction and Standards

The court conducted de novo review of the denial of summary judgment. While such denials are ordinarily not appealable, the collateral-order doctrine permits interlocutory review of qualified immunity (Mitchell v. Forsyth) and Ohio statutory immunity determinations (Chesher v. Neyer). Addressing Johnson v. Jones concerns, the panel reiterated that it retains jurisdiction over the purely legal question whether, taking the plaintiff’s version of facts supported by the record, the law was clearly established (Estate of Carter; Hall v. Navarre).

Importantly, video evidence controls where it “blatantly contradicts” a party’s version of events (Scott v. Harris; Griffin v. Hardrick). Here, the dashcam did not foreclose the plaintiffs’ account on sobriety indicia, so the court credited plaintiffs’ version at summary judgment (Bell v. City of Southfield).

Prolonged Traffic Stop and Reasonable Suspicion

Precedents Cited and Their Influence

• Rodriguez v. United States: A stop may not be extended beyond the time reasonably required to handle the mission of the stop absent reasonable suspicion of another offense. Even a 7–8 minute extension can violate the Fourth Amendment.
• Green v. Throckmorton (6th Cir. 2012): In the OVI context, mere confusion, slow reactions, or prior minor traffic violations, without reliable indicia of intoxication, may be insufficient to create reasonable suspicion; where factual disputes exist about the indicia, the case must go to the jury.
• United States v. Jordan; United States v. Campbell: Reasonable suspicion requires specific and articulable facts; it is more than a hunch.
• Bradley v. Reno (6th Cir. 2015): Time of night, odor of alcohol, glassy eyes, slurred speech, and similar cues are recognized factors in OVI reasonable-suspicion analysis.

Legal Reasoning

The panel accepted that the initial stop for a marked-lanes violation was valid. But video showed at least an eight-minute prolongation—longer than reasonably necessary to issue a citation—triggering the need for reasonable suspicion under Rodriguez and Throckmorton. Taking plaintiffs’ version of the contested facts as true (no odor of alcohol, no slurred speech, no glassy eyes, steady gait), the remaining factors—time of night, one full cross of the center line on a left turn plus several touches of the centerline, and slow compliance in unlocking the trunk—did not compel reasonable suspicion as a matter of law. Under Throckmorton, those circumstances present a jury question. Because Throckmorton was published well before 2020, the right was clearly established, defeating qualified immunity for Salamon at this stage.

Arrest and Probable Cause in OVI Investigations

Precedents Cited and Their Influence

• Alabama v. White: Reasonable suspicion is a lower threshold than probable cause; thus, failure to meet the former typically defeats the latter.
• Miller v. Sanilac County (6th Cir. 2010): Questionable field sobriety test administration undermines probable cause; a jury should resolve factual disputes about test validity absent corroborating indicia.
• Kinlin v. Kline (6th Cir. 2014): Refusal to submit to sobriety testing, standing alone, cannot supply probable cause.
• Green v. Throckmorton: Invalid or disputed sobriety test results, without other indicia, do not create probable cause as a matter of law.

Legal Reasoning

As to Salamon, the probable-cause analysis mirrored the reasonable-suspicion deficiencies, with one added piece of evidence: the HGN test and Amanda’s refusal to perform other tests (due to footwear). Plaintiffs’ expert opined Amanda’s lazy eye rendered HGN inappropriate and that Salamon administered it incorrectly. Combined with the absence of corroborating indicators (as credited at summary judgment), the court held that disputed HGN results plus refusal to perform other FSTs cannot establish probable cause as a matter of clearly established Sixth Circuit law (Throckmorton; Miller; Kinlin). The wrongful-arrest claim therefore proceeds to a jury.

Backup Officer Liability: No Clearly Established Duty in DUI Context

Precedents Cited and Their Influence

• Troutman v. Louisville Metro Dep’t of Corr.; Taylor v. Mich. Dep’t of Corr.: Supervisory liability under § 1983 requires encouragement, participation, authorization, approval, or knowing acquiescence—not mere presence.
• Fazica v. Jordan; Floyd v. City of Detroit; Smith v. Heath: Bystander liability requires presence plus opportunity to intervene in a known constitutional violation.
• Qualified-immunity canon (Mullenix v. Luna; Kisela v. Hughes): Clearly established law must place the question beyond debate in the specific context.

Legal Reasoning—The New Practical Rule

The court found no Sixth Circuit or Supreme Court authority clearly establishing that a backup officer at a DUI stop incurs § 1983 liability merely by arriving mid-stop, monitoring another occupant, and failing to scrutinize a colleague’s sobriety testing and arrest decision. Absent law making that duty clear in the drunk-driving context, qualified immunity attaches. The court reversed the denial of qualified immunity and entered judgment for Officer Parks on the wrongful-arrest claim.

Practical upshot: In the Sixth Circuit, there is presently no clearly established rule that a backup officer at an OVI scene must police the arresting officer’s field-sobriety protocols on pain of personal liability, at least on the facts presented here (mere presence, no direct participation, no obvious use of excessive force).

Municipal Liability and Pendent Appellate Jurisdiction

Precedents Cited and Their Influence

• Monell v. Dep’t of Social Services; Arrington-Bey v. City of Bedford Heights: Failure-to-train liability requires a constitutional violation attributable to municipal policy or deliberate indifference in training.
• King v. City of Rockford (6th Cir. 2024): On interlocutory appeal, courts exercise pendent jurisdiction over Monell issues only when they are inextricably intertwined with the qualified-immunity determination and necessarily resolved by it.

Legal Reasoning

Because the court held that claims against Salamon survive qualified immunity, municipal liability tied to his conduct would depend on policy/training questions not resolved by the qualified-immunity analysis—placing those issues beyond the appellate court’s interlocutory reach under King. However, the failure-to-train theory premised on Parks’s conduct fails as a matter of law because the court found no underlying constitutional violation by Parks. The panel thus reversed the City’s Monell exposure only insofar as it derived from Parks, leaving the district court’s remaining Monell rulings intact for later proceedings.

Curtilage, Knock-and-Talk, and the Absence of a Search or Seizure

Precedents Cited and Their Influence

• Florida v. Jardines; Collins v. Virginia; United States v. Dunn: The curtilage is afforded the same Fourth Amendment protections as the home against unreasonable searches.
• Widgren v. Maple Grove Township; United States v. Jones: A trespass without an attempt to find information or effects is not itself a search; the Fourth Amendment protects against unreasonable searches and seizures.
• Watson v. Pearson; United States v. Baker; Kentucky v. King: The knock-and-talk doctrine permits officers to approach a residence, knock, and request to speak or ask consent to enter, as any private citizen might, so long as they do not linger or exceed the implicit license.

Legal Reasoning

The driveway entry—20–30 yards from the home—did not effect a search or seizure. The officers accompanied Amanda home post-booking, briefly stepped onto the driveway, exchanged words with Patrick, and asked for permission to secure her firearm in a vehicle in the garage. The Catons refused, retrieved the firearm themselves, and the encounter ended. Even assuming the driveway is curtilage, the officers’ conduct fell within the knock-and-talk rubric and did not involve a search of effects or a seizure of persons or property. The court therefore reversed and granted summary judgment to both officers on this Fourth Amendment claim.

Ohio Tort Claims and Statutory Immunity

Framework and Definitions

Ohio Rev. Code § 2744.03(A) provides immunity to political-subdivision employees for acts connected to governmental functions, unless an exception applies—relevant here, § 2744.03(A)(6)(b), which withdraws immunity for conduct done “with malicious purpose, in bad faith, or in a wanton or reckless manner.” Ohio courts define:

• Malice: a willful, intentional design to do injury or an improper purpose (Radvansky v. City of Olmsted Falls; Criss v. Springfield Township).
• Bad faith: a dishonest purpose, conscious wrongdoing, breach of a known duty through an ulterior motive or ill will (Cook v. Cincinnati).

False Arrest/False Imprisonment (Salamon)

Under Ohio law, false arrest and false imprisonment share elements: intentional detention and unlawfulness of the detention (Rogers v. Barbera; Hodges v. Meijer). Because the court held a triable question exists on probable cause for Amanda’s arrest, unlawfulness is likewise a jury question. On statutory immunity, plaintiffs adduced evidence of bad faith: an ulterior motive to maintain OVI arrest statistics, alleged improper HGN administration, and statements that could be viewed as an after-the-fact narrative for the dashcam. Those allegations, if credited, could meet the “bad faith” exception. The court affirmed the denial of summary judgment and statutory immunity on this tort.

Malicious Prosecution (Salamon)

Elements: malice in instituting or continuing the prosecution; lack of probable cause; and favorable termination (Bickerstaff v. Lucarelli). Amanda’s acquittal satisfies favorable termination; the federal probable-cause analysis supports lack of probable cause; and Ohio law allows malice to be inferred from the absence of probable cause (Wright v. City of Euclid). Coupled with the alleged improper purpose, the court affirmed denial of summary judgment and statutory immunity.

Intrusion upon Seclusion (Both Officers)

Ohio recognizes intrusion upon the plaintiff’s seclusion, solitude, or private affairs where an unwarranted intrusion in a private area would be offensive or objectionable to a reasonable person (Piro v. Franklin Township; Contadino v. Tilow; Dickson v. Direct Energy). The district court denied summary judgment but did not analyze the statutory immunity exception under § 2744.03(A)(6)(b). The Sixth Circuit vacated and remanded for the district court to apply the malice/bad-faith/wanton/reckless standard in the first instance.

Complex Concepts Simplified

• Reasonable suspicion vs. probable cause:
  • Reasonable suspicion: specific, articulable facts suggesting criminal activity; more than a hunch but less than probable cause.
  • Probable cause: a fair probability, based on the totality of circumstances, that a crime has been committed. If the facts don’t meet reasonable suspicion, they cannot meet the higher probable cause threshold.
• Prolonged stop (Rodriguez rule): Once the tasks tied to the initial traffic stop are complete, officers cannot extend the stop—even briefly—without reasonable suspicion of another offense.
• HGN test: A field sobriety test assessing involuntary eye movements that may correlate with intoxication. Its probative value depends on medical suitability and correct administration; contested or improperly administered tests carry reduced weight.
• Refusal to perform FSTs: In the Sixth Circuit, a driver’s refusal alone does not create probable cause for arrest (Kinlin).
• Qualified immunity: Shields officials unless they violate a constitutional right that was clearly established at the time, such that every reasonable officer would know the conduct was unlawful in the specific context.
• Bystander/supervisory liability: An officer may be liable for another’s constitutional violation if he encourages, participates in, or knowingly acquiesces in it, or fails to intervene when he has an opportunity and knows of the violation. This case finds no clearly established duty on a backup officer at a DUI stop to police another officer’s sobriety testing on the facts presented.
• Curtilage and knock-and-talk: The curtilage is protected like the home, but the Fourth Amendment still requires a search or seizure. Approaching a residence and asking to speak or to enter—with no “lingering” beyond implied license—falls within the knock-and-talk exception and is not a search.
• Ohio statutory immunity: Public employees are generally immune unless they act with malicious purpose, in bad faith, or in a wanton or reckless manner. Lack of probable cause can support inferences of malice in malicious-prosecution claims.

Impact and Practical Implications

For Law Enforcement

• Prolonged stops: Officers must be able to articulate objective indicators beyond time of night and minor lane deviations to extend a stop for OVI investigation. Absent corroborating cues (odor, slurred speech, glassy eyes, coordination issues), extending the stop risks Fourth Amendment violation.
• HGN and FSTs: Ensure medical suitability for HGN and follow established protocols. Document the cues observed. Do not assume a refusal to perform FSTs supplies probable cause; seek corroborating indicators or alternative investigative steps.
• Backup roles: Backup officers are currently protected by qualified immunity in this specific DUI context absent clearly established duties. Still, best practices include observing and documenting, and intervening when a constitutional violation is apparent (e.g., clear lack of basis or use of force).
• Home encounters: Brief entry onto driveways and requests to speak or secure property are generally permissible under knock-and-talk, but lingering, searching property without consent, or coercive conduct risks constitutional exposure.

For Plaintiffs’ and Defense Counsel

• Summary judgment strategy: Dashcam/bodycam evidence is pivotal; where it does not “blatantly contradict” plaintiffs’ account, factual disputes about indicia of intoxication should reach a jury.
• HGN challenges: Medical ineligibility and administration errors can be dispositive on probable cause; expert testimony is influential in creating triable issues.
• Bystander claims: After this decision, plaintiffs should be prepared to identify authority clearly establishing a backup officer’s duty in the specific OVI/sobriety-testing context or plead and prove knowing acquiescence with an opportunity to intervene.
• Monell appeals: Interlocutory appellate review is narrow; unless inextricably intertwined with qualified-immunity issues, Monell questions will await final judgment.
• Ohio tort immunity: Lack of probable cause can support inferences of malice and bad faith; evidence of ulterior motives (e.g., quota-like incentives) may defeat immunity at summary judgment.

On Precedential Value

Although designated “not recommended for publication,” this decision offers persuasive guidance in the Sixth Circuit on several recurring issues: the limits of prolonged OVI stops, the evidentiary weight of contested HGN results and refusals, the current contours of backup officer liability in DUI arrests, and the necessity of a search or seizure for curtilage-based claims.

Conclusion

The Sixth Circuit’s decision in Caton v. Salamon delivers three core messages. First, under clearly established law, prolonging a traffic stop for OVI investigation requires specific, reliable indicators of intoxication; disputed HGN results and a refusal to perform additional tests—without corroborating signs—do not establish probable cause. Second, at least on the facts here, no clearly established law imposes § 1983 liability on a backup officer for failing to scrutinize a colleague’s DUI testing and arrest decision, entitling such an officer to qualified immunity. Third, curtilage claims require proof of a search or seizure; brief driveway presence and requests for consent fall within the knock-and-talk doctrine and do not violate the Fourth Amendment.

On the state-law side, Ohio tort claims for false arrest/false imprisonment and malicious prosecution can survive statutory immunity where evidence supports lack of probable cause and bad faith. The intrusion-upon-seclusion claim returns to the district court to apply the statutory immunity standard.

Taken together, the opinion sharpens the evidentiary requirements for OVI stops and arrests, narrows immediate exposure for backup officers absent clearly established duties, and reaffirms the centrality of “search or seizure” to curtilage protections—all while signaling the limits of interlocutory review of Monell claims in the Sixth Circuit.