--- title: "Expert Testimony Curtailed in Defective Conveyor Case" meta: "og:description": "Court partially excludes testimony of safety expert George J. Wharton in a conveyor injury case, allowing design opinions but barring legal and speculative claims." "og:title": "Expert Testimony Curtailed in Defective Conveyor Case" author: "Expert Witness Profiler" description: "Court partially excludes testimony of safety expert George J. Wharton in a conveyor injury case, allowing design opinions but barring legal and speculative claims." --- # Expert Testimony Curtailed in Defective Conveyor Case Posted on July 29, 2025 by Expert Witness Profiler In July 2022, while working at Tyoga Container Company’s facility, William Borden stepped onto a mesh belt conveyor manufactured by Mainline Conveyor System, Inc. The conveyor unexpectedly activated and threw him off, causing severe lacerations to his left knee and lower leg. Borden claimed that the conveyor was defective and unreasonably dangerous. In August 2023, Borden filed a strict liability lawsuit against Mainline in the Pennsylvania Court of Common Pleas of Tioga County. The following month, Mainline removed the case to federal court on diversity grounds. Borden sought to exclude testimony from Mainline’s engineering expert, [George J. Wharton](https://expertwitnessprofiler.com/expert-witness/George-Wharton/1529630); evidence suggesting product misuse or highly reckless conduct; evidence of assumption of risk; and evidence of his prior DUI conviction. ## **Safety Engineering Expert Witness** [George J. Wharton](https://expertwitnessprofiler.com/expert-witness/George-Wharton/1529630) is a professional engineer with multiple certifications, including C.F.E.I., C.V.F.I., and C.F.P.S., and holds both B.S. and M.S. degrees in mechanical engineering. Wharton serves as an expert in engineering, safety engineering, and personal injury matters. His work includes evaluating mechanical system design, workplace safety procedures, and incident causation. Wharton has also authored expert reports responding to opposing experts’ claims and opining on industry practices based on decades of engineering experience. [Get the full story on challenges to George J. Wharton’s expert opinions and testimony with an in-depth Challenge Study.](https://expertwitnessprofiler.com/order/add?eId=1529630&pId=2) ## **Discussion by the Court** ### **Contract Interpretation** Wharton’s opinion that Tyoga was “required” to assume safety responsibilities under its contract with Mainline crossed into legal interpretation. Since his conclusion relied on contract language rather than engineering practices, the court deemed it inadmissible. ### **Design vs. Knowledge** Wharton did not offer an opinion on Mainline’s subjective knowledge. Instead, he responded to the opposing expert’s foreseeability claim by analyzing the design differences between conveyors. This design-focused rebuttal was found admissible. ### **Speculation on Plaintiff’s Behavior** Wharton asserted that a warning decal wouldn’t have influenced Borden’s decision to cross the conveyor. This opinion was based on speculation about Borden’s mindset and was therefore excluded as outside the scope of expert testimony. ### **Alarm System Commentary** Wharton’s critique of an audio-visual alarm system addressed practical feasibility—highlighting how excessive alarms could lead to desensitization or muting. Grounded in engineering experience, this testimony was allowed. ### **Post-Accident Procedures** The Court excluded any opinion referencing Tyoga’s post-accident policies, including a sign in Wharton’s report, under the parties’ pretrial agreement. ## **Held** The Court granted in part and denied in part Plaintiff Borden’s motion to exclude the testimony of Defendant Mainline’s expert witness, George J. Wharton. ## **Key Takeaway**: An engineering expert may testify about industry practices, product design, and the feasibility of safety features, but cannot interpret contractual obligations or speculate on a party’s mental state or motivations. Courts will exclude expert opinions that cross into legal conclusions or subjective speculation. ## **Case Details:** --- ## **You Might Also Like** ![Human Resources Expert Allowed to Opine on Termination](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-22T200052.311.jpg) [**Human Resources Expert Allowed to Opine on Termination**](https://expertwitnessprofiler.com/expert-testimony-curtailed-in-defective-conveyor-case/human-resources-expert-allowed-to-opine-on-termination)![Neuropsychology Expert Not Allowed to Opine on Cognitive Decline](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-22T144728.528.jpg) [**Neuropsychology Expert Not Allowed to Opine on Cognitive Decline **](https://expertwitnessprofiler.com/expert-testimony-curtailed-in-defective-conveyor-case/neuropsychology-expert-not-allowed-to-opine-on-cognitive-decline)![Human Factors Expert Not Allowed to Opine on the Tile](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-21T191749.960.jpg) [**Human Factors Expert Not Allowed to Opine on the Tile**](https://expertwitnessprofiler.com/expert-testimony-curtailed-in-defective-conveyor-case/human-factors-expert-not-allowed-to-opine-on-the-tile)![Insurance Expert Not Allowed to Opine on Legal Duties](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-21T155751.487.jpg) [**Insurance Expert Not Allowed to Opine on Legal Duties**](https://expertwitnessprofiler.com/expert-testimony-curtailed-in-defective-conveyor-case/insurance-expert-not-allowed-to-opine-on-legal-duties)![Law And Legal Expert Not Allowed to Opine on Contract Formation](https://ewp-blog.expertwitnessprofiler.org/wp-content/uploads/2026/04/blog-pic-640X480-2026-04-20T213123.718.jpg) [**Law And Legal Expert Not Allowed to Opine on Contract Formation**](https://expertwitnessprofiler.com/expert-testimony-curtailed-in-defective-conveyor-case/law-and-legal-expert-not-allowed-to-opine-on-contract-formation)