Tree Step Expert WitnessesIn a recent products liability case, a plaintiff alleged that he was injured when he fell 25 feet from a tree while installing a tree step. Defendants, who manufactured and distributed the tree steps, didn’t dispute that the tree step broke or that there was an inclusion in it. However, they argued that the tree step wouldn’t have broken if it had been fully installed. To support this contention, they pointed to the testimony of their own experts on this point.

U.S. District Judge Elizabeth K. Dillon was asked to consider Defendant’s expert opinions regarding topics other than engineering, including opinions concerning the warnings and instructions associated with the tree step, the tree harness, and their warnings.

In one of Plaintiff’s arguments, he argued that Defendant’s expert wasn’t an expert in the field of accident reconstruction or metallurgy, nor was he a hunter safety expert. As a result, some of his opinions that touched on those topics should be excluded, Plaintiff contended. Plaintiff noted that, although Defendant’s expert claimed to be a human factors expert as it pertained to hunting products, he had no specific training and had taken only basic undergraduate level classes in product design.

Plaintiff also asserted that because Defendant’s expert’s lack of training, experience, and education in these areas—and along with his general lack of data—it should preclude some of his opinions. Defendants responded that its expert relied on other experts from other fields to support his opinions, which was permissible.

The judge agreed that an expert may not merely “parrot the conclusion of another expert, without adding anything from his own field of expertise.” However, Defendant’s expert was permitted to rely on Defendant’s other expert witnesses, as well as Plaintiff’s own testimony concerning what Plaintiff understood about the products or warnings, in order to reach some of his opinions. Judge Dillon found that based on her review, Defendant’s expert’ opinions fell in the category of opinions that “occasionally rely on, but then add to, other experts’ opinions.”

As part of this challenge, Plaintiff argued that all of Defendant’s expert’s opinions concerning the tree step, the tree harness, and the warnings on them were inadmissible. According to Plaintiff, Defendant’s expert offered no scientific foundation for these opinions. He simply opined as to what the instructions were, whether they were clear, and the foreseeability of a reasonable person following the instructions. He included a string cite to various cases requiring testing by a human factors expert to offer such opinions. In his reply, Plaintiff conceded that Defendant’s expert was qualified regarding the warning labels of tree stands and harnesses, but those weren’t the products at hand and thus were irrelevant. He also claimed that Defendant’s expert wasn’t qualified to opine on the warnings and labels of a tree step and his lack of testing meant his opinions on this should be excluded.

Defendants responded that its expert had testified repeatedly about his analysis concerning warnings and instructions and whether those warnings and instructions were followed. He was a voting member of the Tree stand Sub-Committee of ASTM, which is tasked with reviewing tree stands and their components, as well as the warnings and instructions that accompany them. The judge said they called Plaintiff’s argument that he wasn’t qualified to offer such opinions as “absurd.”

Given his qualifications and expertise in creating and evaluating warning labels of products including tree steps, and the court’s rulings on in limine motions allowing evidence of other products used by Plaintiff and allowing evidence regarding Plaintiff’s knowledge of products and review of manuals and warnings, Judge Dillon concluded that opinions on these topics were relevant, and would be helpful to the trier of fact. Although Plaintiff challenged that such opinions weren’t admissible due to a lack of “testing” or a “scientific basis,” he failed to identify what types of testing should be done and didn’t challenge any specific opinion as unreliable.

Plaintiff next contended that Defendant’s expert shouldn’t be able to offer opinions criticizing the finite element analysis performed by Plaintiff’s experts, because he wasn’t sufficiently familiar with the model used or how the values he criticizes were incorporated into that model. He also argued that Defendant’s expert wasn’t an expert on finite element analysis, wasn’t “comfortable enough” to build a model on it, and as such, he shouldn’t be permitted to offer opinions on the propriety of the finite element analysis used by Plaintiff’s experts.

The judge disagreed. Defendant’s expert testified that he wasn’t comfortable with using the software package that Plaintiff’s expert used in the analysis, but he also testified that he understood the type of analysis employed and its purposes. Additionally, his reports offered specific critiques of the model and the data used by Plaintiff’s experts. As a result, the judge permitted these opinions.

The judge concluded that most of the opinions identified by Plaintiff weren’t within the common knowledge of jurors and that expert testimony would be helpful to the trier of fact.

Given the expert’s vast experience with hunting products and their safe use, warnings associated with such products, and his accident reconstruction experience, Judge Dillon held that he could offer such opinions.

Plaintiff’s motion to exclude Defendant’s expert was granted in part and denied in part.


Wilhelm v. Ameristep Corp.,2018 U.S. Dist. LEXIS 202944 (W.D. Va. November 30, 2018)