Court limits the testimony of Chemical Engineering Expert Witness after it is found to consist of an improper legal opinion

Court limits the testimony of Chemical Engineering Expert Witness after it is found to consist of an improper legal opinion

This case arose from a fire at the vacant home of Richard F. Vetter and Bryan Miner (collectively, “Plaintiffs”) on March 9, 2021. The Plaintiffs were renovating their home and had applied Varathane Classic Wood Stain, manufactured by Defendant Rust-Oleum Corporation, to their wood floors. After applying the stain, they left the applicators saturated in the product at the home. A fire then occurred, which Plaintiffs alleged was caused by the spontaneous combustion of the applicators soaked with Varathane. In response, the Defendant, for the purpose of the pending motions, does not contest the Plaintiffs’ claim that the rags caught fire spontaneously. 

Following the incident, the Burlington County Fire Marshal conducted an investigation and concluded that the probable ignition sequence involved the spontaneous combustion of stain-soaked rags and rollers, leading to the ignition of available combustible material in the area and resulting in a self-sustaining fire. All wood stains, including Varathane, are composed of drying oils, semi-drying oils, and drying agents to properly cure the product. These substances undergo oxidation while they cure, or dry, releasing heat. The presence of drying agents accelerates oxidation. If the heat generated during this process is unable to escape, there exists a potential risk of spontaneous combustion.

The Varathane wood stain label featured a warning about the risk of spontaneous combustion, along with instructions on how to prevent such incidents. The front of the product label included a prominent warning stating that the liquid and vapor are combustible, with potential harm if swallowed. The back panel contained a specific caution outlined in red, emphasizing the danger of spontaneous combustion for items like rags and steel wool if improperly discarded. The warning instructed users to place such materials in a sealed, water-filled, metal container immediately after use. Additionally, disposal guidelines were provided, advising users to dispose of contaminated absorbent, container, and unused contents in compliance with local, state, and federal regulations.

As a result of the fire incident, the Plaintiffs initiated legal action by asserting claims against the Defendant. These claims included strict liability, negligence, and breach of implied warranty. The basis for all these claims was the alleged failure to provide adequate warnings and a design defect related to spontaneous combustion. More specifically, the Plaintiffs contended that the Varathane label did not contain sufficient warning regarding the risk of spontaneous combustion. Furthermore, they argued that Varathane should have been designed to eliminate any potential risk of spontaneous combustion. 

The Plaintiffs enlisted the services of engineering expert Jennifer Morningstar, who authored reports examining the involvement of Varathane in the fire that occurred at the Plaintiffs’ home in March 2021. Morningstar underwent a deposition on January 10, 2023.

In her report, Morningstar provided an explanation of the spontaneous combustion process and the role of drying oils and agents in that process. She specifically discussed the drying oils present in the Defendant’s wood stain product. Morningstar’s opinion highlighted the hazard of spontaneous combustion in oil-based wood stains due to the curing reaction of the drying oils. She recommended eliminating this hazard by excluding drying oils and agents from the product. Morningstar pointed out that wood stains, including those sold by the Defendant, could use water as a carrying medium for pigment instead of oil, categorizing them as waterborne, water-based, or acrylic. According to her, stains in this category, lacking drying oils and agents, did not pose the hazard of spontaneous combustion associated with their use.

In formulating her opinion, Morningstar relied on a report from the National Fire Protection Association and several studies discussing waterborne coating wood stains, among other documents. Her ultimate opinion, as outlined in her report, asserted that Rust-Oleum’s Varathane Classic Penetrating Wood Stain was defectively designed because a reasonably safer design, in the form of a waterborne substitute product, existed. Morningstar contended that this alternative product would have prevented harm without substantially impairing the reasonably anticipated or intended function of Varathane. She emphasized the clear safety benefits of altering the design, outweighing any potential disadvantages associated with the proposed alternative design, including any diminished usefulness. This opinion was reiterated in her rebuttal report, where she explained that the presence of water in waterborne wood stains is what eliminates the spontaneous combustion hazard from these substances.

Defendant moved for summary judgment, arguing the claims were preempted by federal law and that its warnings were adequate. Defendant also moved to preclude testimony from Plaintiffs’ expert Jennifer Morningstar. Plaintiffs cross-moved for partial summary judgment on the affirmative defenses.

Chemical Engineering Expert Witness

Jennifer Morningstar, a professional engineer licensed in 2017 and Certified Fire and Explosion Investigator. She is President and Senior Consulting Engineer of Warren Forensics, where she performs specialized consulting related to property loss and unintentional injuries resulting from industrial accidents, fire, and explosions. Morningstar has an undergraduate degree in chemical engineering from Virginia Polytechnic Institute and State University, as well as a Masters of Business Administration from the University of South Carolina. As an expert witness, Morningstar has been deposed several times in litigation matters. She also has experience, as a chemical engineer, working on the production of chemical products involving polymer and polymerization, though not specifically involving wood stains. She also has general experience with drying oils and additives.

Discussions by the Court

The Defendant filed a motion to preclude Morningstar from offering testimony, asserting that she lacked the qualifications to provide opinions on oil-based or water-based wood stains. The motion contended that Morningstar’s testimony was not grounded in reliable methodologies.

The admissibility of expert witness testimony in this case was governed by Federal Rule of Evidence 702 and the Daubert standard, which outlines three factors: the expert’s qualifications, the reliability of their methodology, and whether the testimony is pertinent to the matters at issue in the case. Citing, In re Paoli R.R. Yard PCB Litig. (In Re Paoli I), 35 F.3d 717, 741-43 (3d Cir. 1994), the Third Circuit emphasized the preference for admitting evidence sure to be of potential assistance to the trier of fact, but maintained the obligation to ensure reliability. Rule 702 was recently amended to require a demonstration from the proponent that the proffered testimony is more likely than not to meet admissibility requirements.

The Defendant contested the qualifications and reliability of Morningstar, focusing on the first two factors in the Daubert analysis. The Court, henceforth, limited its analysis to these aspects. Regarding Morningstar’s qualifications, the Defendant argued that she was not qualified to express opinions on oil-based wood stains. In contrast, the Plaintiffs asserted that Morningstar, being a chemical engineer, was well-qualified to provide opinions on various aspects, including the spontaneous combustion phenomenon, the composition of the Defendant’s product, its chemical propensity for hazards, a review of spontaneous combustion events related to such products, and the feasibility of an alternative, safer design for wood finishes. The Court sided with the Plaintiffs, agreeing with Morningstar’s qualifications in this context.

The Court, in evaluating the qualifications for an expert, emphasized a liberal approach, acknowledging that a broad range of knowledge, skills, and training could qualify an individual. The Third Circuit had previously expressed satisfaction with generalized qualifications. The Court deemed it an abuse of discretion to exclude testimony merely based on the expert not being considered the best qualified or lacking specific specialization. Despite the Defendant’s argument that Morningstar lacked a postgraduate degree and specific experience with wood stains, the Court did not narrowly interpret the requisite experience for qualifying as an expert in this case.

Morningstar possessed a chemical engineering degree, held a professional engineering license, and was certified as a fire and explosion investigator. With a background and experience that included serving as an expert witness in other lawsuits, she had specifically provided expertise in two cases concerning the involvement of wood stains in house fires. Given her qualifications and expertise, the Court determined that Morningstar was certainly qualified to express opinions on topics such as the process of spontaneous combustion, the role of drying agents in that process, the presence of drying agents in wood stains, and the existence of alternative products in the market. The Court held that these subjects fell within the scope of her background as a chemical engineer and fire and explosion investigator.

The Court noted that the strengths and weaknesses of an expert’s qualifications are typically considered in evaluating the weight of their testimony rather than its admissibility, citing Holbrook v. Lykes Bros. S.S. Co., 80 F.3d 777, 782 (3d Cir. 1996). Morningstar’s opinion in this case included the assertion that there was already an alternative product available on the market. The Court concluded that in Morningstar’s case, no such issues concerning the practicality of the recommended safety features and their familiarity with the relevant safety standards were present, as she opined that the water-based wood stain, already on the market, served as a viable alternative to the oil-based wood stain.

In assessing the reliability of Morningstar’s opinion, the Court applied the standard that when an expert testifies to scientific knowledge, their opinions must be grounded in scientific methods rather than subjective belief or unsupported speculation. The expert should have sound grounds for their belief. The Court considered the following factors to determine the reliability of expert opinions. These factors include whether the method involves a testable hypothesis, has undergone peer review, has a known or potential rate of error, maintains standards, is generally accepted, relates to established reliable methods, reflects the qualifications of the expert, and has non-judicial applications. 

Courts possess considerable discretion in determining the reliability of expert opinions, as highlighted in Betterbox Commc’ns Ltd. v. BB Techs., Inc., 300 F.3d 325, 329 (3d Cir. 2002). In cases involving defective design, the Court typically considers various factors to assess reliability. These factors include federal design and performance standards, standards established by independent organizations, relevant literature, evidence of industry practice, product design and accident history, illustrative charts and diagrams, data from scientific testing, the feasibility of suggested modifications, and the risk-utility of such modifications.

The Plaintiffs contended that certain considerations in assessing reliability have limited relevance in this case. Morningstar’s opinion asserted that an existing product on the market was comparable to and safer than Varathane, without proposing new modifications. Therefore, factors such as the feasibility of suggested modifications and the risk-utility of those suggested modifications were deemed not particularly useful in this context.

The Defendant’s representation of Morningstar’s overall opinion is deemed inaccurate by the Court. Morningstar opined that Varathane’s risks could be mitigated with the existence of a safer design. While she did not explicitly mention the Consumer Product Safety Commission (CPSC) or its lack of cautionary labels for spontaneous combustion risk, the Court did not consider this omission as detrimental to the reliability of her opinion. Morningstar’s focus was not on mandating label identification of spontaneous combustion risk for Varathane. Instead, she asserted that the risk was reduced in water-based wood stains, an existing market product. Morningstar relied on the Safety Hierarchy, a standard she considered universally known, to support her opinion that the risk presented by oil-based wood stains could be eliminated. Additionally, she referred to literature, fire incident reports, and data to discuss the frequency of fires involving oil-based wood stains. Morningstar also delved into the distinctions in product design and substances between oil- and water-based wood stains.

The absence of any testing conducted by Morningstar does not automatically cast doubt on the reliability of her opinion, according to the Court, citing In re Rail Freight Fuel Surcharge Antitrust Litig., 292 F. Supp. 3d. 14, 76-77 (D.D.C. 2017), that rejected similar arguments, the Court stated that challenges related to the absence of certain analyses do not qualify as Daubert arguments, as they do not inherently question the reliability of the work performed by the expert. Overall, the Plaintiffs successfully demonstrated that it was more likely than not that Morningstar’s testimony met the admissibility requirements under Rule 702. The Court expressed confidence in the ability of the Defendant’s counsel to conduct vigorous cross-examination, present contrary evidence, and provide careful instructions on the burden of proof, allowing a jury to determine the weight afforded to Morningstar’s opinion. However, the Court agreed that Morningstar could not testify to the defective design of the product as it constituted an impermissible legal conclusion at the time of trial.

The Defendant filed a motion for summary judgment, asserting that State Farm-which it argues to be the real party in interest—having twice previously litigated this issue unsuccessfully, is now collaterally estopped from contesting the preemption of its warnings claim by the Federal Hazardous Substances Act (FHSA), that Plaintiffs’ claim is preempted by the FHSA, and that the Varathane label provides sufficient warning under the FHSA. Additionally, the Defendant argued that the Plaintiffs lacked necessary expert testimony to support their design defect claim, and even if Morningstar’s testimony was admitted, it would not satisfy the burden to establish a design defect. In response, the Plaintiffs filed a cross-motion for summary judgment on their failure-to-warn claim, contending that the FHSA does not preempt their claims. The Court determined that summary judgment was appropriate for Plaintiffs’ failure-to-warn claim but denied summary judgment for Plaintiffs’ defective design claim.

The Defendant asserted that the Plaintiffs’ failure-to-warn claim is both expressly and impliedly preempted by the Federal Hazardous Substances Act (FHSA). In response, the Plaintiffs filed a cross-motion seeking summary judgment on any affirmative defense asserting preemption or limitation by the FHSA. The Court aligned with the Defendant’s position, in line with the consensus of many other federal Courts, and concluded that the Plaintiffs’ claim was preempted by the FHSA.


The Court granted in part and denied in part Rust-Oleum’s motion to preclude Plaintiff’s Expert Jennifer Morningstar’s testimony. The Court granted in part and denied in part Rust-Oleum’s motion for summary judgment, granting judgment on the failure-to-warn claim but denied summary judgment as to Plaintiffs’ defective design claim. The Court denied Plaintiffs’ cross-motion for partial summary judgment. The Court has not arrived on an outcome for this case since the remaining issues involved in this case still await resolution.

Key Takeaways 

In a legal case involving a fire allegedly caused by a wood stain product, the admissibility of expert testimony played a crucial role. The Court, guided by Federal Rule of Evidence 702 and the Daubert standard, assessed the qualifications and reliability of the engineering expert, Jennifer Morningstar. Despite the Defendant’s challenges to Morningstar’s qualifications, emphasizing her lack of postgraduate degree and specific experience with wood stains, the Court adopted a liberal approach in evaluating qualifications. Morningstar’s chemical engineering degree, professional engineering license, certification as a fire and explosion investigator, and prior experience as an expert witness in similar cases were deemed sufficient. The Court emphasized that the strengths and weaknesses of an expert’s qualifications are factors for weighing testimony, not excluding it.

Regarding the reliability of Morningstar’s opinion, the Court applied factors such as testability, peer review, error rate, standards, general acceptance, relationship to established methods, expert qualifications, and non-judicial uses. Morningstar’s reliance on existing market products as alternatives and her focus on eliminating risks rather than proposing modifications influenced the Court’s assessment. The Court acknowledged Morningstar’s use of established standards like the Safety Hierarchy and her reference to literature, fire incident reports, and data in forming her opinions. The absence of testing conducted by Morningstar was not deemed a decisive factor against reliability.

Ultimately, the Court found that Morningstar’s testimony met the admissibility requirements under Rule 702. The Court expressed confidence in the adversarial process, emphasizing the role of vigorous cross-examination, presentation of contrary evidence, and careful jury instructions in assessing the weight of Morningstar’s opinions. However, the Court ruled that Morningstar could not testify to the defective design of the product as it constituted an impermissible legal conclusion.