Coffman Is Not a Bright-Line Bar to Failure-to-Warn Claims Involving Combined Use of Two Sound Products

1. Introduction

In Sarah Elizabeth Woodruff v. Ford Motor Company (Tenn. July 21, 2026), the Supreme Court of Tennessee addressed the reach of its earlier decision in Coffman v. Armstrong International, Inc., 615 S.W.3d 888 (Tenn. 2021), in the context of a Tennessee Products Liability Act (TPLA) failure-to-warn claim.

The case arises from a catastrophic three-vehicle collision in Knoxville. Six-year-old Ethan Woodruff, seated in a Dorel booster seat, was restrained using a Ford-branded seatbelt extender purchased on eBay and installed in a vehicle (a 2012 Nissan Juke) for which the extender was not designed. Ethan suffered severe injuries. Plaintiff Sarah Woodruff brought TPLA claims alleging inadequate warnings/instructions about using a seatbelt extender with a child booster seat.

After a mistrial in the Ford portion of the litigation, the trial court certified a Rule 9 interlocutory question: whether Coffman “requires dismissal as a matter of law” of Woodruff’s failure-to-warn claim against Ford because the alleged risk arose from using Ford’s extender in combination with another manufacturer’s product (the booster seat). The Court of Appeals (in Woodruff v. Ford Motor Co., No. E2023-00889-COA-R9, 2024 WL 2270675 (Tenn. Ct. App. May 20, 2024) (“hereinafter Ford”)) read Coffman broadly and ordered dismissal. The Supreme Court reversed, clarifying that Coffman does not mandate such dismissal as a categorical matter.

2. Summary of the Opinion

The Court held that Coffman v. Armstrong International, Inc. does not require dismissal as a matter of law of Woodruff’s failure-to-warn claim against Ford merely because the alleged hazard materialized when Ford’s product was used with another manufacturer’s product. The Court emphasized that Coffman addressed a narrow factual and statutory problem: “post-sale integration” of asbestos-containing parts made and sold by others into equipment that was not asbestos-containing when it left the defendants’ control.

The Court did not decide whether Ford actually owed a duty to warn, whether the extender was “defective” or “unreasonably dangerous” under the TPLA, whether the warnings were adequate, or causation. Those questions were outside the certified interlocutory issue. The case was remanded for further proceedings.

3. Analysis

A. Precedents Cited

1) The anchor precedent: Coffman v. Armstrong International, Inc.

In Coffman, an equipment mechanic claimed mesothelioma due to workplace asbestos exposure arising from asbestos-containing materials integrated into equipment after sale. The Supreme Court construed the TPLA to hold that equipment manufacturers could not be “held liable for injuries resulting from products they did not make, distribute, or sell,” and that the duty to warn under the TPLA attaches to the condition of the manufacturer’s own product “only if it was defective or unreasonably dangerous at the time the manufacturer transfers control of the product.” The Court repeatedly cautioned that its decision was limited to “post-sale integration of asbestos-containing parts manufactured and sold by others.”

In Woodruff, the Court treated Coffman as controlling only within its defined setting (non-dangerous equipment plus post-sale integration of a distinct, inherently dangerous third-party product creating a new “end-product”), and rejected the Court of Appeals’ attempt (in “Ford”) to elevate Coffman into a broad “combined-use” no-duty rule.

2) Scope-of-review authorities (Rule 9 interlocutory appeals)

The Court relied on Metro. Gov't of Nashville & Davidson Cnty. v. Tenn. Dep't of Educ., 645 S.W.3d 141 (Tenn. 2022), and Funk v. Scripps Media, Inc., 570 S.W.3d 205 (Tenn. 2019), to emphasize that in a Tenn. R. App. P. 9 appeal, review is limited to the certified question. This procedural frame is consequential: the Court’s opinion is a clarification of what Coffman does (and does not) decide, not a final merits determination on duty, defect, warning adequacy, or causation.

3) Tennessee products-liability context: Davis v. Komatsu Am. Indus. Corp.

The Court cited Davis v. Komatsu Am. Indus. Corp., 42 S.W.3d 34 (Tenn. 2001), as an example of the TPLA’s capacity—depending on the context— to impose liability relating to component parts and a defective final product. The citation underscores the Court’s central methodological point: TPLA duty/liability questions in “combined product” scenarios are context-sensitive, and Coffman is not a one-size-fits-all rule for every interaction between products made by different manufacturers.

4) Out-of-state “combined-use” taxonomy cases (persuasive, not controlling)

To illustrate that “combined product” cases come in different factual subsets, the Court cited multiple jurisdictions that distinguish between (a) integrating an inherently dangerous third-party product into a sound product and (b) using two independently sound products together in a way that creates risk:

  • O'Neil v. Crane Co., 266 P.3d 987 (Cal. 2012) (no duty to warn re post-sale asbestos integration).
  • Tellez-Cordova v. Campbell-Hausfeld/Scott Fetzger Co., 28 Cal. Rptr. 3d 744 (Cal. Ct. App. 2004) (risk from combination of two sound products).
  • Rastelli v. Goodyear Tire & Rubber Co., 591 N.E.2d 222 (N.Y. 1992) (discussing when combination of sound products may trigger a duty; holding no duty on its facts).
  • Ilosky v. Michelin Tire Corp., 307 S.E.2d 603 (W. Va. 1983) (cited by Rastelli).
  • Macias v. Saberhagen Holdings, 282 P.3d 1069 (Wash. 2012) and Braaten v. Saberhagen Holdings, 198 P.3d 493 (Wash. 2008) (recognizing an exception where two sound products combine to create an unreasonably unsafe condition).

These citations function less as adoption of another state’s test and more as support for the Tennessee Court’s refusal to turn Coffman into a categorical bar: the opinion signals that the “duty to warn” analysis may vary across “combined-use” scenarios.

5) Foreseeable misuse / intended use illustrations (briefed examples)

In a footnote, the Court listed cases reflecting different “foreseeable misuse” and “intended use” approaches, including: Goins v. Clorox Co., 926 F.2d 559 (6th Cir. 1991) (applying Tennessee law), Kirsten v. W.M. Barr & Co., No. 97 C 0002, 1997 WL 136328 (N.D. Ill. Mar. 19, 1997), Martin v. Interstate Battery Sys. of Am., Inc., No. 12-CV-184-JED-FHM, 2016 WL 4275740 (N.D. Okla. Aug. 12, 2016), and Barbosa v. Hopper Feeds, Inc., 537 N.E.2d 99 (Mass. 1989). The Court did not apply or adopt these frameworks; it used them to show that combined-use duty questions are often analyzed through foreseeability or intended/anticipatable use lenses—issues left open on remand.

B. Legal Reasoning

The Court’s reasoning is a structured clarification of precedent, anchored in statutory interpretation and fidelity to the question certified. It proceeds in four main steps:

  1. Procedural constraint (Rule 9): The Court confined itself to whether Coffman mandates dismissal as a matter of law, not whether Ford wins on duty, defect, warning adequacy, misuse, or causation.
  2. Return to the TPLA’s text: The Court reiterated the core statutory concepts governing strict products liability and failure-to-warn claims:
    • TPLA coverage includes “breach of or failure to discharge a duty to warn or instruct.” (Tenn. Code Ann. § 29-28-102(6)).
    • Liability requires that “the product is determined to be in a defective condition or unreasonably dangerous at the time it left the control of the manufacturer or seller.” (Tenn. Code Ann. § 29-28-105(a)).
    • “Defective condition” turns on whether a product is unsafe for “normal or anticipatable handling and consumption.” (Tenn. Code Ann. § 29-28-102(2)).
    • “Unreasonably dangerous” is defined via consumer-expectation and prudent-manufacturer formulations. (Tenn. Code Ann. § 29-28-102(8)).
    • Subsequent “unforeseeable” alteration or abnormal use breaks liability. (Tenn. Code Ann. § 29-28-108).
    These provisions supply the vocabulary for analyzing whether the alleged combined use was “anticipatable” or “foreseeable” at the time of transfer—without turning the mere presence of another product into a categorical defense.
  3. Confining Coffman to its factual/legal predicate: The Court distinguished Coffman on the ground that it involved a non-dangerous product allegedly made dangerous only after the defendant’s transfer of control, by integration of a different product (asbestos-containing materials) “neither manufactured nor sold” by the defendants. That is, in Coffman the asserted danger was tied to the third-party asbestos product, not the defendant’s product “as sold.”
  4. Rejecting a bright-line “combined use” bar: The Court stated that Ford pointed to no TPLA language “that relieves Ford of a duty to warn simply because” a foreseeable misuse of Ford’s product “involves another manufacturer’s product as well.” Thus, whatever the merits of Woodruff’s warning theory, Coffman does not compel judgment as a matter of law.

Notably, the Court carefully avoided creating the opposite bright-line rule. It did not hold that a duty exists whenever two sound products are used together; rather, it held only that Coffman does not pre-answer that question for all cases.

C. Impact

The decision’s immediate precedential effect is clarifying and limiting: Coffman cannot be cited as an automatic, categorical basis to dismiss every TPLA failure-to-warn claim involving interaction with another manufacturer’s product.

1) Practical litigation consequences in Tennessee

  • More fact-sensitive duty/warning litigation: Defendants will have a harder time obtaining dismissal/summary judgment solely by characterizing the injury as arising from “use with another product.” Courts will likely have to engage the statutory questions the Supreme Court highlighted: whether the alleged risk made the defendant’s product unsafe for “normal or anticipatable” handling when it left the defendant’s control, and whether the use was “unforeseeable” abnormal use under § 29-28-108.
  • Cabining asbestos “bare metal / post-sale integration” arguments: In practice, Coffman remains potent in its core setting (post-sale integration of asbestos products made and sold by others), but Woodruff discourages stretching that rationale to all “combined product” scenarios.
  • Procedural signal in interlocutory appeals: The Court’s insistence on the certified-question boundary reinforces that parties should not expect a Rule 9 appeal to resolve the entire product-liability case; it will resolve only the discrete legal issue certified.

2) Doctrinal trajectory

Woodruff positions Tennessee to confront, in future cases, the more difficult “combined-use of two sound products” question on the merits—potentially including: what “anticipatable handling” means when a product is commonly misused with another product; how much knowledge of misuse matters; and how warning feasibility and clarity fit within TPLA definitions of “defective condition” and “unreasonably dangerous.” The Court deliberately left these issues open.

4. Complex Concepts Simplified

Failure to warn (TPLA)
A product can be considered “defective” or “unreasonably dangerous” not only because of its design or manufacture, but because the manufacturer/seller failed to provide adequate warnings or instructions about non-obvious risks connected to normal or “anticipatable” handling.
“Anticipatable handling” vs. “abnormal use”
The TPLA’s definition of “defective condition” looks to whether the product is unsafe for “normal or anticipatable” handling. Separately, § 29-28-108 relieves liability where a product becomes unreasonably dangerous due to “subsequent unforeseeable ... abnormal use.” In plain terms: foreseeable misuse may still be “anticipatable,” while unforeseeable misuse may break the chain of liability.
Post-sale integration / “end-product”
This describes a scenario where the buyer (or someone else) adds a different product after purchase—potentially creating a new combined “end-product.” Coffman addressed a specific version: non-dangerous equipment later combined with third-party asbestos-containing materials.
“Coffman bar” (what it is—and is not)
Coffman is not a universal rule that “no manufacturer ever has a duty to warn when another manufacturer’s product is involved.” It is a statutory holding that, in the asbestos post-sale integration setting, the TPLA does not impose a duty on equipment manufacturers to warn about dangers from asbestos products they did not make, sell, or distribute.
Rule 9 interlocutory appeal
An appeal taken mid-case on a narrow, certified legal question. The appellate court does not decide everything; it decides only what is within the certified question’s scope.

5. Conclusion

The Supreme Court of Tennessee in Sarah Elizabeth Woodruff v. Ford Motor Company established an important clarifying rule: Coffman v. Armstrong International, Inc. does not mandate dismissal as a matter of law of a TPLA failure-to-warn claim merely because the alleged harm arises from combined use of the defendant’s product with another manufacturer’s product.

The opinion’s significance lies in what it prevents: an overbroad reading of Coffman that would collapse diverse “combined product” scenarios into a single no-duty category. By remanding without deciding duty or defect, the Court preserved a fact- and statute-driven inquiry centered on the TPLA’s concepts of control, timing, and foreseeability/anticipatability.