Independent Investigation Breaks Cat’s-Paw Causation in ADEA Pretext Challenges

1. Introduction

Carmen Tafoya, a long-tenured billing specialist in the City of Fountain’s utilities department, was terminated after an internal investigation concluded she used City resources and customer account information for a personal landlord-tenant matter (including accessing a prospective tenant’s account and sharing details with family). At the time of termination, Tafoya was 72.

Tafoya sued under the ADEA, asserting the City’s stated policy-violation rationale was a pretext for age discrimination. Her central theory on appeal was a “cat’s-paw” theory: that biased subordinates (including a supervisor who reported her conduct and officials who briefed the City Manager) manipulated the ultimate decisionmaker into firing her because of age.

The key issues were:

• Whether Tafoya produced sufficient evidence of pretext under the ADEA at summary judgment; and
• Whether a cat’s-paw theory could survive where the City conducted an independent investigation and the plaintiff failed to connect alleged omissions/misstatements to age-based discriminatory intent.

2. Summary of the Opinion

The Tenth Circuit affirmed summary judgment for the City. Even assuming Tafoya could satisfy the initial steps of the McDonnell Douglas Corp. v. Green framework, she failed at the pretext stage. Her cat’s-paw theory failed for two independent reasons:

• No but-for causation as to the reporting supervisor, because an independent investigation “broke the causal chain”; and
• No evidence of discriminatory intent as to other alleged influencers (HR Director, City Attorney, Utilities Director), because the claimed “omissions” in briefing the City Manager did not support an inference of age-based intent.

Because summary judgment was proper even considering the stricken declaration, the panel declined to decide whether the district court abused its discretion in striking it.

3. Analysis

A. Precedents Cited

1) Summary-judgment standard

• Lazy S Ranch Props., LLC v. Valero Terminaling & Distrib. Co. — The court reiterated de novo review of summary judgment and the rule that facts/inferences are viewed in the nonmovant’s favor. This anchored the appellate posture: Tafoya received the benefit of favorable inferences, but still needed evidence sufficient for a rational factfinder.
• Adler v. Wal-Mart Stores, Inc. — Quoted (via Lazy S Ranch Props.) for the definition of a “genuine” issue: enough evidence that a rational trier could resolve it either way. The court’s use underscores that conjecture and generalized suspicion do not create triable disputes.

2) ADEA burden and McDonnell Douglas sequencing

• Bennett v. Windstream Commc'ns, Inc. — Provided two core propositions: (i) the ADEA plaintiff’s “ultimate burden” is to prove intentional age discrimination; and (ii) the typical use of the McDonnell Douglas Corp. v. Green burden-shifting framework (prima facie case → legitimate reason → pretext).
• McDonnell Douglas Corp. v. Green — The foundational indirect-proof framework. The panel strategically assumed the first steps were met and focused on pretext, which is common where the employer offers a clear nondiscriminatory reason (policy violations) and the dispute is whether that reason is a cover.
• Iweha v. Kansas — Cited for the court’s approach of “concentrating on pretext,” allowing the panel to bypass contested prima facie issues. It also supplied cat’s-paw principles later relied upon through Sellman.

3) Cat’s-paw liability and its elements

• Sellman v. Aviation Training Consulting, LLC — The controlling articulation of the Tenth Circuit cat’s-paw test at summary judgment, including the three elements the plaintiff must place in genuine dispute:
  1. Subordinate action motivated by discriminatory intent;
  2. Intent to cause an adverse employment action; and
  3. The subordinate action was the but-for cause of the adverse employment action.

  Sellman also supplied the key definitional idea: the biased subordinate “uses the formal decision-maker as a dupe.”

• Singh v. Cordle and Thomas v. Berry Plastics Corp. — These cases furnished the “break the causal chain” doctrine: an independent investigation by higher-level decisionmakers (or an independent process) can sever causation between a biased subordinate’s actions and the termination decision. The panel used this principle to reject cat’s-paw causation as to Robinson because the City Attorney’s office conducted an independent investigation with multiple interviews, including Tafoya’s.

4) “Animus” versus “intent” in discrimination framing

• Bostock v. Clayton County — Cited (through Murray) for the point that “animosity” is not required; discrimination can exist without hostility.
• Murray v. UBS Sec., LLC — Used to support replacing “animus” with “intent” in describing the first cat’s-paw element, aligning the terminology with Supreme Court guidance.
• Ashaheed v. Currington — Clarified the conceptual difference: intentional discrimination means intent to treat differently; animus is hostility and is not necessary.

5) Appellate preservation (forfeiture/waiver)

• Savant Homes, Inc. v. Collins — Applied to reject Tafoya’s new appellate argument that McDonnell Douglas should not apply to cat’s-paw cases. Because she did not raise it below and did not substantively argue plain-error review on appeal, the argument was waived.

6) Comparator evidence and “similarly situated” employees

• MacKenzie v. City & Cnty. of Denver — Provided the comparator standard: a similarly situated employee engaged in the same conduct without differentiating or mitigating circumstances.
• Lincoln v. BNSF Ry. Co. — Noted as partially abrogating MacKenzie on other grounds, but the comparator principle quoted remained operative for the panel’s purpose.

---

B. Legal Reasoning

1) The court’s choice to decide the case at “pretext”

The panel assumed (without deciding) that Tafoya could satisfy the prima facie case and that the City articulated a legitimate, nondiscriminatory reason (policy violations). It then asked the decisive question: could a rational jury find that the City’s reason was pretext for age discrimination?

2) Cat’s-paw as the exclusive pretext pathway argued—and why it failed

Tafoya’s pretext argument was largely cat’s-paw: the decisionmaker (City Manager Trainor) lacked discriminatory motive, but biased subordinates allegedly steered him toward termination.

a) Robinson: causation severed by independent investigation

Even if Robinson initiated the complaint, the City conducted an investigation by Assistant City Attorney Parker, who interviewed multiple witnesses including Tafoya. Under Singh v. Cordle and Thomas v. Berry Plastics Corp., such an independent investigation can “break the causal chain,” defeating the third cat’s-paw element (but-for causation). The court thus rejected the theory as to Robinson without needing to decide whether Robinson was biased.

b) Brisnehan, Johnson, and Blankenship: no evidence of discriminatory intent

Tafoya argued these officials misled Trainor by not emphasizing: (1) other employees did not recall a deposit-waiver request; (2) Daniel may have disclosed confidential information and was not investigated; and (3) Tafoya’s direct supervisor was not consulted.

The panel’s response was structurally important: even if the “omissions” occurred, Tafoya failed to connect them to age-based discriminatory intent (the first cat’s-paw element under Sellman v. Aviation Training Consulting, LLC). The court further stressed evidentiary gaps:

• Tafoya had admitted (per the report) to asking to see if a deposit could be waived, weakening the factual premise of the “they didn’t recall it” argument.
• There was no evidence these officials knew Daniel violated policies; and Tafoya had admitted Blankenship was not aware of other similar breaches.
• It was “unclear” how failure to disclose the supervisor-not-consulted point evidenced discriminatory intent.

Without evidence of age-linked intent, the cat’s-paw theory could not create a triable issue of pretext.

c) Comparator “red herring”: Daniel not similarly situated

In a footnote, the court additionally undermined Tafoya’s attempt to rely on Daniel as a comparator. Under MacKenzie v. City & Cnty. of Denver, comparators must have engaged in the same conduct without meaningful differentiators. Here, the panel identified differentiating circumstances: Daniel allegedly provided information to a coworker, while Tafoya sought it for personal gain and then shared it with non-City employees. The court also noted the uncertainty whether Daniel even accessed confidential information (“may have”).

3) Stricken evidence: immaterial to the outcome

The panel declined to decide whether the district court properly struck Miller’s declaration because, even if considered, it would not change the summary judgment analysis. The court observed (in a footnote) that speculation about “younger employees” manipulating supervisors was too generic to create a genuine dispute on material facts—illustrating the recurring summary judgment theme from Adler v. Wal-Mart Stores, Inc.: generalized assertions cannot substitute for concrete, admissible evidence tied to the challenged decision.

---

C. Impact

1) Practical tightening of cat’s-paw proof at summary judgment

Although unpublished, Tafoya reinforces a demanding, element-by-element approach to cat’s-paw liability in ADEA cases:

• Independent investigations matter. When an employer can show an investigation with witness interviews and a report reviewed by the decisionmaker, plaintiffs face a steep climb to show the subordinate’s initial report was the but-for cause of termination.
• Intent must be tied to age. Alleged process defects or incomplete briefings do not themselves imply discriminatory intent. Plaintiffs must link the subordinate’s conduct to age-based intent and show it materially drove the outcome.

2) Guidance to employers

The decision implicitly signals best practices: use neutral investigators (here, a city attorney), document interviews and findings, and ensure the decisionmaker reviews investigative materials rather than relying solely on potentially biased summaries. Such steps strengthen defenses against cat’s-paw claims by showing a causation break under Singh/Thomas.

3) Guidance to plaintiffs

Plaintiffs relying on cat’s-paw should expect courts to demand:

• Evidence the purported influencer harbored age-based discriminatory intent (not merely unfairness or procedural irregularities);
• Evidence the influencer intended the adverse action; and
• Evidence the influencer’s conduct was but-for causal despite any independent investigation (for example, showing the investigation was not independent, was tainted, or was mere rubber-stamping).

4. Complex Concepts Simplified

5. Conclusion

Tafoya v. City of Fountain affirms that, in ADEA cases pursued through a cat’s-paw theory, plaintiffs must do more than point to workplace disputes, asserted investigative omissions, or uneven enforcement. They must produce evidence that a subordinate acted with age-based discriminatory intent, meant to cause the adverse action, and was the but-for cause of termination.

Critically, the opinion reinforces a powerful defense: an employer may defeat cat’s-paw causation by conducting an independent investigation that supports the termination decision, consistent with Singh v. Cordle and Thomas v. Berry Plastics Corp.. Even as a nonprecedential decision, the case provides a clear roadmap for how the Tenth Circuit evaluates pretext and cat’s-paw causation at summary judgment.