CAFA Jurisdiction Tracks the Operative Amended Complaint: Dropping (and Repleading) Class Allegations Can Remove (and Restore) Federal Jurisdiction

I. Introduction

Thor Zurbriggen, et al. v. Twin Hill Acquisition, Inc., et al. is a Seventh Circuit decision arising from widespread employee complaints following American Airlines’ 2016 rollout of new uniforms manufactured by Twin Hill. Hundreds of employees reported symptoms ranging from irritation to severe allergic reactions, including claimed “proximity reactions” allegedly triggered merely by being near the uniforms.

Seventy-four named plaintiffs sued American and Twin Hill in the Northern District of Illinois, initially invoking federal jurisdiction under the Class Action Fairness Act (CAFA), 28 U.S.C. § 1332(d)(2), and pleading both products-liability theories (strict liability and negligence) and intentional torts (battery and intentional infliction of emotional distress). After extensive litigation, the district court excluded plaintiffs’ causation/defect experts and granted summary judgment to defendants.

On appeal, the Seventh Circuit largely adopted the district court’s opinion, but wrote to address two matters of broader significance: (1) whether the district court retained subject-matter jurisdiction under CAFA after plaintiffs amended their pleading to “drop” class claims, and (2) whether plaintiffs could salvage products-liability claims through res ipsa loquitur or Illinois’s Tweedy-style inference of defect.

II. Summary of the Opinion

  • CAFA jurisdiction: The court held that CAFA jurisdiction depends on whether the operative complaint is “filed under rule 23.” Applying the Supreme Court’s reasoning in Royal Canin U.S.A., Inc. v. Wullschleger, the court concluded an amended complaint can “remake” the suit and alter jurisdictional grounds. Here, even if plaintiffs’ third amended complaint undermined CAFA by disclaiming class pursuit, their fourth amended complaint “re-filed” the action as a class action and restored CAFA jurisdiction at the time summary judgment was entered.
  • Merits—experts and intentional torts: The court incorporated by reference the district court’s rulings excluding plaintiffs’ experts and rejecting intentional tort theories, leaving plaintiffs without evidence of defect and causation.
  • Res ipsa / Tweedy: The court rejected plaintiffs’ attempts to use (a) Illinois’s strict-liability inference recognized in Tweedy v. Wright Ford Sales, Inc. and (b) traditional res ipsa loquitur for negligent manufacturing. The claimed injuries did not “speak for themselves,” causation was not obvious, alternative causes were plausible, and “exclusive control” was lacking given the distribution chain, washing, wear, and intermediaries.

III. Analysis

A. Precedents Cited

1. Jurisdiction and CAFA

Chi. Tchrs. Union, Loc. 1 v. Educators for Excellence, Inc. and Knopick v. Jayco, Inc. anchored the panel’s threshold point: appellate courts must independently verify subject-matter jurisdiction, whether or not the parties press the issue.

The traditional Seventh Circuit approach to CAFA had been shaped by Cunningham Charter Corp. v. Learjet, Inc., which held that post-filing developments—such as failing to achieve or pursue class certification—do not defeat CAFA jurisdiction because CAFA asks whether the action was “filed under Rule 23.” This aligns with familiar “time-of-filing” principles discussed in Sykes v. Cook Inc. (amount in controversy) and Winforge, Inc. v. Coachmen Indus., Inc. (citizenship).

The potential doctrinal disruption came from the Supreme Court’s Royal Canin U.S.A., Inc. v. Wullschleger, which emphasized that plaintiffs control their suit not only at inception but through amendment: an amended pleading can “effectively remake the suit,” including its “jurisdictional basis.” The panel read Royal Canin—though decided in a removal/supplemental-jurisdiction posture—as reiterating a broader rule for “original federal cases” that jurisdiction “follows the amended … pleading,” citing Rockwell v. Int'l Corp. v. United States.

This placed Seventh Circuit authority In re Burlington Santa Fe Railway in tension. Burlington had stated CAFA jurisdiction remained secure even after an amendment eliminating class allegations (in a removal context). The panel did not overrule Burlington (noting the issue was not “squarely presented”), but flagged that future CAFA removal cases must grapple with the post–Royal Canin tension.

Finally, Morrison v. YTB Int'l, Inc. appeared as a reminder of CAFA’s mandatory-declination provisions in some class actions, though those exceptions were not disputed.

2. Products liability, defect inference, and res ipsa

The court framed Illinois products-liability doctrine through Salerno v. Innovative Surveillance Tech., Inc. and Blue v. Env't Eng'g, Inc., distinguishing strict liability (product condition-focused) from negligence (conduct-focused) but emphasizing that both require proof that the product caused injury.

For strict liability’s ordinary requirements—particularly the usual need for expert testimony to identify defect and causation—the court cited DiCosolo v. Janssen Pharms., Inc., Kirk v. Clark Equip. Co., and Mikolajczyk v. Ford Motor Co.. It also relied on its own articulation of strict-liability expectations in Bensenberg v. FCA US LLC.

Plaintiffs’ primary doctrinal vehicle, Tweedy v. Wright Ford Sales, Inc., permits an inference of defect in strict liability without identifying a specific defect when a product fails to perform as reasonably expected and abnormal use or reasonable secondary causes are excluded. The panel contextualized Tweedy’s logic using colorful language from Welge v. Planters Lifesavers Co.—the idea that while fanciful alternatives (“Elves”) are imaginable, some malfunctions strongly support an inference of defect.

However, the court emphasized that Tweedy does not eliminate the need to connect injury to the product’s condition, citing Parker v. Freightliner Corp. for the distinction between inferring defect-at-sale versus proving that injury resulted from product condition.

To show Tweedy’s typical domain—observable failure or malfunction—the court cited malfunction cases: Varady v. Guardian Co., Alvarez v. Am. Isuzu Motors, Pike v. ABSS Mfg. Co., Weedon v. Pfizer, Inc., and again DiCosolo. Those cases feature a tangible product failure (collapse, transmission failure, ladder collapse, device malfunction, lethal dose release) from which defect and causation are more readily inferred.

For traditional res ipsa loquitur in negligence, the court relied on Johnson v. Armstrong (probability and exclusive-control elements; and that applicability is initially a question of law for the court). It also cited Ruark v. Union Pac. R.R. for the general principle that the event must “speak for itself.”

B. Legal Reasoning

1. The jurisdiction holding: “filed under Rule 23” can be undone—and redone—by amendment

The Seventh Circuit’s key jurisdictional move was to synthesize CAFA’s definition of a “class action” with Royal Canin’s amendment principle:

  • CAFA jurisdiction requires that the civil action be “filed under rule 23,” 28 U.S.C. § 1332(d)(1)(B).
  • Under Royal Canin U.S.A., Inc. v. Wullschleger, an amended complaint can “effectively remake the suit,” including its jurisdictional basis; jurisdiction in original cases tracks the operative amended pleading.

Applying that framework, the court treated plaintiffs’ third amended complaint—which announced plaintiffs “elected to drop their class claims” and that they would not seek class certification—as potentially removing the case from CAFA’s “filed under Rule 23” requirement, despite earlier CAFA-invoking pleadings.

But plaintiffs’ fourth amended complaint deleted the class-disclaiming language and pleaded CAFA jurisdiction “unambiguously.” Under Royal Canin’s “remake” concept, that amendment operated as a functional re-filing under Rule 23 sufficient to secure CAFA jurisdiction again at the critical time: when the district court entered summary judgment.

The doctrinal upshot is a nuanced (and practically important) refinement: CAFA jurisdiction is not merely “sticky” based on the first filing; it can be lost if plaintiffs amend away the class-action nature of the suit, and it can be restored if a later operative complaint again pleads the action as a Rule 23 class action.

2. The merits holding on products liability: res ipsa cannot substitute for causation proof where mechanism is uncertain

After expert exclusion, plaintiffs’ products-liability case faced a foundational problem: no admissible evidence tied the alleged medical effects—especially “proximity reactions”—to a defect in the uniforms. The panel’s res ipsa/Tweedy analysis explains why inferential doctrines could not bridge that evidentiary gap.

Tweedy’s strict-liability inference failed for two independent reasons:

  1. Causation gap: Tweedy-style reasoning can help infer a defect’s existence without pinpointing the precise defect, but it does not automatically prove that the plaintiffs’ injuries “resulted from a condition of the product.” The court stressed that Tweedy addresses defect-at-sale and expected performance, not the medical causation problem posed by varied symptoms and uncertain exposure mechanisms.
  2. No “failure” and no exclusion of secondary causes: Unlike brakes, ladders, crutches, transmissions, or implanted devices, the uniforms did not “malfunction” in the conventional sense. Further, the plaintiffs could not exclude reasonable alternative explanations, particularly given differing symptoms, differing medical histories, and other plausible sources (including post-production contamination).

Traditional res ipsa loquitur failed on both elements:

  • Probability element: The record did not support that these symptoms “ordinarily” occur only in the presence of negligence in manufacturing—especially where testing (Intertek, NIOSH, and others) did not find a pattern indicating a chemical or metal contamination cause.
  • Exclusive control element: Distribution through multiple intermediaries, global shipping, and subsequent washing and wear defeated any claim that Twin Hill retained the kind of exclusive control res ipsa requires.

C. Impact

1. CAFA pleading strategy and jurisdictional “toggle” risk

The most consequential aspect of the opinion is its treatment of CAFA jurisdiction as sensitive to amended pleadings. Litigants often assume CAFA jurisdiction—once properly invoked—cannot be lost by later litigation choices short of formal remand or dismissal. This decision signals a more dynamic reality after Royal Canin:

  • Plaintiffs who expressly abandon class treatment in an operative complaint may strip the case of CAFA jurisdiction, at least in original-filing contexts (and perhaps in removal contexts once Burlington’s tension is resolved).
  • Plaintiffs may also be able to restore CAFA jurisdiction by repleading Rule 23 class allegations—raising timing, forum, and tactical considerations (including whether a jurisdictional “gap” matters for prior orders).
  • District judges may more actively police CAFA jurisdiction midstream when amended pleadings change the nature of the case, rather than assuming “once CAFA, always CAFA.”

2. Limits of Tweedy/res ipsa in toxic exposure and medically heterogeneous injury claims

On the merits, the opinion draws a boundary around inferential defect doctrines in products cases involving complex medical causation. When:

  • the alleged harm mechanism is uncertain,
  • symptom profiles are diverse,
  • alternative causes are plausible,
  • and control is dissipated through supply chains and post-sale handling,

courts are unlikely to permit plaintiffs to proceed without reliable expert proof by invoking Tweedy or res ipsa. The decision thus reinforces a broader trend: inferential doctrines cannot be used to evade gatekeeping under Rule 702 where scientific/medical causation is the central contested issue.

IV. Complex Concepts Simplified

CAFA (“Class Action Fairness Act”) jurisdiction
A federal jurisdiction statute that allows large class actions meeting certain requirements (including minimal diversity and $5 million aggregate amount in controversy) to be heard in federal court. One key requirement is that the case be a “class action,” i.e., “filed under rule 23.”
“Time-of-filing” vs. “operative pleading” jurisdiction
Many jurisdictional facts are fixed at the time the case begins. But Royal Canin emphasizes that when a plaintiff amends the complaint, the amendment can “remake” the lawsuit—including its jurisdictional footing—so jurisdiction in original cases may track what the current (operative) complaint alleges.
Strict products liability vs. negligent manufacturing
Strict liability focuses on whether the product was defective and unreasonably dangerous; negligence focuses on whether the defendant failed to use reasonable care. In practice, both often require proof that the product caused the injury.
Tweedy doctrine
An Illinois strict-liability inference allowing a plaintiff to proceed without identifying a specific defect when a product fails to perform as expected and other reasonable causes are excluded. It is most naturally applied to “malfunction” scenarios where the failure itself strongly indicates defect.
Res ipsa loquitur
A negligence doctrine allowing an inference of negligence when the event ordinarily does not occur absent negligence and the instrumentality was in the defendant’s exclusive control. It is not a shortcut when control is shared and alternative explanations are plausible.
Expert exclusion under Rule 702
Federal courts act as gatekeepers to ensure expert testimony is based on reliable methods and fits the case. When the causal mechanism is scientific/medical and experts are excluded, plaintiffs often cannot prove defect and causation.

V. Conclusion

The Seventh Circuit affirmed summary judgment for American and Twin Hill, adopting the district court’s exclusion of plaintiffs’ experts and rejecting plaintiffs’ efforts to rely on Tweedy and res ipsa loquitur to prove defect and causation.

The opinion’s broader significance lies in its jurisdiction analysis: read alongside Royal Canin U.S.A., Inc. v. Wullschleger, CAFA jurisdiction is tied to the operative amended pleading. Plaintiffs who amend to disclaim class treatment may amend themselves out of CAFA jurisdiction—and, conversely, may restore CAFA jurisdiction by later repleading class allegations. On the merits, the decision underscores that inferential defect doctrines are ill-suited to complex, medically variable exposure claims where causation is not self-evident and where control over the product is diffuse.