CGIA Emergency-Vehicle Immunity Turns on a Disjunctive “Lights-or-Siren” Showing, and the District Court Must Find Whether the Siren Was Used

1. Introduction

Murphy v. Marlow (10th Cir. Sept. 8, 2026) arises from a high-speed nighttime collision in Kiowa County, Colorado. Plaintiffs Dale and Anna Murphy and the Estate of Donna Murphy sued Deputy Jacob Marlow and the Kiowa County Sheriff’s Office in a diversity action asserting negligence-based tort claims (including wrongful death) stemming from Marlow’s emergency response driving.

The central issue on appeal was not liability on the merits but jurisdictional immunity under the Colorado Government Immunity Act (CGIA)—specifically, whether the defendants retained immunity because the deputy’s vehicle qualified for the CGIA’s emergency-vehicle carveout tied to compliance with Colorado’s emergency-driving signaling statutes.

Procedurally, defendants brought an interlocutory appeal after the district court denied their Rule 12(b)(1) motion to dismiss for lack of subject matter jurisdiction based on CGIA immunity.

2. Summary of the Opinion

The Tenth Circuit exercised interlocutory jurisdiction under the collateral order doctrine and vacated the district court’s denial of immunity to the extent it concluded there was a waiver of sovereign immunity, remanding for further proceedings.

The panel agreed with the district court’s factual-handling of the lights evidence (post-collision photos) and found no clear error in the district court’s determination that the vehicle’s visible emergency light placement did not satisfy the “mounted as high as practicable” requirement of Colo. Rev. Stat. § 42-4-213(2).

But the panel held the district court’s immunity analysis was incomplete because it failed to make necessary findings on a disputed point: whether Marlow used an audible signal (siren). Relying on the Colorado Supreme Court’s more recent decision in Hice v. Giron, the panel construed Colo. Rev. Stat. § 42-4-108(3) as imposing a disjunctive “lights-or-siren” requirement, meaning immunity could hinge on siren use even if lighting placement was deficient.

3. Analysis

3.1 Precedents Cited

  • Sawyers v. Norton, 962 F.3d 1270 (10th Cir. 2020)
    Role: Provided the jurisdictional gateway. The court relied on Sawyers for the proposition that orders denying dismissal based on state-law immunity from suit are immediately appealable under the collateral order doctrine. It also framed the CGIA as conferring immunity from suit (not merely a defense to liability), making interlocutory review appropriate.
  • Aspen Ortho. & Sports Med., LLC v. Aspen Valley Hosp. Dist., 353 F.3d 832 (10th Cir. 2003)
    Role: Reinforced that CGIA immunity is immunity from suit, supporting interlocutory appellate jurisdiction when immunity is denied.
  • Kenney v. Helix TCS, Inc., 939 F.3d 1106 (10th Cir. 2019)
    Role: Supplied the standard of review for Rule 12(b)(1) rulings (de novo), which the panel applied to the district court’s dismissal denial and statutory interpretation.
  • Baker v. USD 229 Blue Valley, 979 F.3d 866 (10th Cir. 2020)
    Role: Anchored the doctrinal distinction between facial and factual Rule 12(b)(1) attacks, and confirmed the district court’s discretion to consider evidence (affidavits/documents and limited evidentiary hearings) to resolve disputed jurisdictional facts—critical to the panel’s remand directive to make findings about siren use.
  • Graff v. Aberdeen Enterprizes, II, Inc., 65 F.4th 500 (10th Cir. 2023)
    Role: Supported the rule that, on a factual jurisdictional attack, the court may not presume complaint allegations are true. The panel used this framework to reject defendants’ claim that the district court improperly “presumed” plaintiffs’ version; the district court relied on photographic evidence instead.
  • Ramos v. Bondi, 155 F.4th 1154 (10th Cir. 2025)
    Role: Provided the definition of “clear error” used to review the district court’s jurisdictional factfinding on light placement. Applying Ramos, the panel concluded defendants failed to show a “definite and firm conviction” of mistake.
  • Maestas v. Lujan, 351 F.3d 1001 (10th Cir. 2003)
    Role: Reinforced appellate limits: the court of appeals does not make factual findings or resolve disputed fact questions. This principle supported deference to the district court’s photo-based findings and underpinned remand—factfinding about siren use belonged in the district court.
  • New Mexicans for Bill Richardson v. Gonzales, 64 F.3d 1495 (10th Cir. 1995)
    Role: Cited for the proposition that a party invoking jurisdiction must present evidence necessary to establish it, supporting the procedural approach of developing a record on the jurisdictional immunity facts (including siren activation).
  • N.H. Ins. Co. v. TSG Ski & Golf, LLC, 128 F.4th 1337 (10th Cir. 2025)
    Role: Provided the Erie/diversity-law rule: federal courts apply the forum state’s substantive law and, when state supreme court authority conflicts or evolves, apply the most recent statement of state law. This was decisive in choosing Hice v. Giron over Tidwell ex rel. Tidwell v. City & Cnty. of Denver.
  • Hice v. Giron, 543 P.3d 385 (Colo. 2024)
    Role: The key state-law authority. The Tenth Circuit treated Hice’s repeated characterization of § 42-4-108(3) as a “lights-or-siren requirement” as reflecting the Colorado Supreme Court’s construction of the statute’s disjunctive language (“audible or visual signals”). The panel used Hice to hold the district court must determine whether the siren was used before concluding immunity was waived.
  • Tidwell ex rel. Tidwell v. City & Cnty. of Denver, 83 P.3d 75 (Colo. 2003)
    Role: Plaintiffs invoked Tidwell for the proposition that emergency vehicles must use both lights and siren (with limited pursuit exceptions). The panel acknowledged Tidwell’s “lights and siren” phrasing but held that in diversity cases it must follow the Colorado Supreme Court’s most recent statement—Hice—rendering Tidwell non-controlling to the extent of tension.

3.2 Legal Reasoning

(a) Jurisdiction and posture. The panel treated the CGIA issue as a Rule 12(b)(1) jurisdictional question because the CGIA confers immunity from suit. That classification matters: it allows early evidentiary consideration and can justify a limited evidentiary hearing to resolve disputed “jurisdictional facts.”

(b) The statutory framework. The panel traced the immunity pathway through three Colorado provisions:

  • CGIA waiver for motor vehicle operation: Colo. Rev. Stat. § 24-10-106(1)(a) waives immunity for injuries resulting from the operation of a public entity’s motor vehicle by a public employee in the course of employment.
  • Emergency-vehicle carveout: That waiver does not apply to “emergency vehicles operating within the provisions of” Colo. Rev. Stat. § 42-4-108(2) and (3).
  • Emergency-driving conditions: § 42-4-108 permits speeding while responding to an emergency call if the driver does not endanger life or property, and the exemption applies “only when such vehicle is making use of audible or visual signals meeting the requirements of section 42-4-213.”

(c) The decisive interpretive move: “audible or visual” is disjunctive. The district court denied immunity based solely on its conclusion that the vehicle’s visual signaling did not satisfy § 42-4-213(2) (“at least one signal lamp mounted as high as practicable”). The Tenth Circuit held this was incomplete because § 42-4-108(3) can be satisfied by either compliant visual signaling or compliant audible signaling—i.e., siren use—consistent with Hice’s “lights-or-siren” characterization.

(d) Remand because factual findings were missing. Whether Marlow activated the siren was disputed. Because the district court made no finding on that point, the panel vacated the immunity denial and remanded with instructions to make the necessary factual findings on siren operation. If the siren was not used, the lights issue could be dispositive; if the siren was used (and satisfies § 42-4-213’s siren/horn requirements), immunity analysis may change.

(e) Deference to the district court on lights. Although defendants attacked the reliability of post-collision photos, the panel held the district court permissibly considered them in a factual 12(b)(1) posture and did not clearly err in finding no high-mounted lighting (e.g., roof, mirror, or windshield-embedded lights) was shown. The panel rejected defendants’ attempt to rely on photos of a different police vehicle to undermine the district court’s factfinding, emphasizing the appellate court’s limited role under clear-error review.

3.3 Impact

1) Practical rule for CGIA emergency-vehicle immunity litigation in federal court (diversity). This decision signals that, when immunity turns on § 42-4-108(3), district courts must address the audible and visual alternatives—especially where the record is disputed—rather than treating visual compliance as the sole gatekeeper.

2) Erie discipline: “most recent state supreme court statement” controls. The panel’s preference for Hice v. Giron over the older phrasing in Tidwell ex rel. Tidwell v. City & Cnty. of Denver illustrates how federal courts will treat evolving state-law signals. Even where an older case used “lights and siren” language, more recent state supreme court treatment of the statute’s disjunctive text can control in diversity cases.

3) Increased salience of jurisdictional fact development. The remand underscores that CGIA immunity disputes can require targeted evidentiary development at the Rule 12(b)(1) stage (affidavits, documents, and potentially a limited hearing) to resolve “jurisdictional facts” such as whether a siren was activated.

4) Substantive incentives for agencies. Although the panel did not ultimately decide immunity, it emphasizes that operational compliance (equipment placement and signal usage) can determine whether a public entity/employee faces suit. Agencies may respond by tightening policies, training, and documentation regarding emergency signal activation and vehicle equipment configurations.

4. Complex Concepts Simplified

  • Sovereign immunity (CGIA): A rule that generally bars tort suits against Colorado public entities/employees unless the CGIA expressly waives immunity. If immunity applies, the court lacks jurisdiction to hear the case.
  • Waiver vs. restoration/carveout: The CGIA may waive immunity for vehicle-operation injuries, but for “emergency vehicles” the waiver is limited if the driver meets § 42-4-108’s conditions—functionally “restoring” immunity in that scenario.
  • Interlocutory appeal / collateral order doctrine: Normally, appeals wait until final judgment. But immunity-from-suit is effectively lost if a defendant must litigate through trial, so denials of such immunity can be appealed immediately.
  • Rule 12(b)(1) facial vs. factual attack: A facial attack assumes the complaint’s facts; a factual attack allows evidence and factfinding to decide jurisdiction. Here, the immunity challenge was factual—so photos and other evidence were fair game.
  • Standards of review: “De novo” means the appellate court re-decides the legal question; “clear error” means factual findings are upheld unless the appellate court is firmly convinced a mistake was made.
  • Disjunctive statutory requirement (“or”): If a statute says “audible or visual,” it typically means either one can satisfy the condition—important here because siren use could independently satisfy § 42-4-108(3) even if lighting placement is disputed.

5. Conclusion

Murphy v. Marlow refocuses CGIA emergency-vehicle immunity analysis on the full statutory text of § 42-4-108(3): an emergency vehicle’s speeding exemption (and thus the immunity carveout) depends on use of audible or visual signals meeting § 42-4-213’s requirements. Guided by Hice v. Giron and Erie principles, the Tenth Circuit held a district court cannot deny immunity based solely on visual-signal defects without also making findings on disputed siren activation. The decision thus both clarifies the operative “lights-or-siren” framework and underscores the necessity of jurisdictional factfinding in CGIA immunity disputes.