Expert Witness Blog

In the recent case of Wingate, E. v. McGrath, D., Pennsylvania Superior Court 2025, the Pennsylvania Superior Court addressed the pivotal role of a Business Valuation Expert Witness in a contentious shareholder dispute. The case provides a compelling illustration of how courts evaluate the reliability and admissibility of expert testimony under Pennsylvania law, with direct implications for the outcome of complex business litigation.

Background and Parties

The dispute arose between Elaine Wingate, a minority shareholder, and Daniel McGrath, the majority shareholder and managing officer of a closely held corporation. Wingate alleged that McGrath had engaged in oppressive conduct and sought a judicial determination of the fair value of her shares following her forced removal from the company. Central to the litigation was the accurate valuation of the business, which would determine the amount owed to Wingate for her equity interest.

Davis v. Globe Machine Manufacturing Co.

A notable case involving a Machine Guarding Expert Witness is Davis v. Globe Machine Manufacturing Co., decided by the Washington Supreme Court in 1984. This case centered on workplace safety, specifically the adequacy of machine guarding on industrial equipment, and provides a clear example of how expert testimony can shape the outcome of litigation involving industrial accidents and alleged product defects. The full opinion is available at Davis v. Globe Machine, 102 Wn.2d 68 (1984).

Background and Facts

Pedro Fidalgo & others v. Columbus McKinnon Corporation

A recent case involving a Latches & Fasteners Expert Witness is Pedro Fidalgo & others v. Columbus McKinnon Corporation, decided by the Massachusetts Court of Appeals in 2002. The case citation is Pedro Fidalgo & others v. Columbus McKinnon Corp., 56 Mass. App. Ct. 176 (2002).

Background and Facts

Davis v. Sig Sauer, Inc.

A recent legal case involving an Ergonomics Expert Witness is Davis v. Sig Sauer, Inc., decided by the United States Court of Appeals for the Sixth Circuit in January 2025. The case citation is Davis v. Sig Sauer, Inc., No. 24-5210 (6th Cir. 2025).

Background and Parties

In the case of E²G v. Ferrellgas, No. 2:22-cv-01234 (D. Utah Dec. 19, 2023), the testimony of a Vibration Analysis Expert Witness was pivotal in diagnosing and resolving issues related to high vibration levels in vertical pumps used in liquid natural gas (LNG) service.

Background of the Case

In October 2021, Ferrellgas installed vertical pumps with 25-stage impellers to handle LNG operations. Initially, the pumps produced higher pressure and flow than required, leading to operational adjustments that resulted in poor motor reliability. In January 2022, two stages were removed, reducing the impellers to 23 stages. A tuning plate was added between the motor base and discharge head to decrease the structural natural frequency of the motor-pump assembly. While vibration amplitudes decreased, in November 2023, one pump exhibited increased vibrations and noise, leading to inspections that revealed wear on the pump shaft and throat bushing.

In the case of Skaggs v. Ferrellgas, No. 2:22-cv-01234 (D. Utah Dec. 19, 2023), the testimony of a Safety Engineering Expert Witness was pivotal in addressing allegations of inadequate safety measures and regulatory compliance concerning propane dispenser operations.

Background of the Case

In November 2021, a propane explosion occurred at a Ferrellgas facility in Utah, resulting in significant property damage and personal injuries. The incident involved a propane dispenser that malfunctioned, leading to the release and ignition of propane gas. Skaggs, a former employee of Ferrellgas, filed a lawsuit alleging that the company failed to implement necessary safety protocols and comply with Occupational Safety and Health Administration (OSHA) regulations, contributing to the explosion.

In the landmark case of Greenman v. Yuba Power Products, Inc., 59 Cal. 2d 57 (1963), the California Supreme Court addressed critical issues in product liability law, particularly concerning the role of expert testimony in establishing manufacturer responsibility for defective products.

Background of the Case

In 1957, Mr. Greenman purchased a Shopsmith, a combination woodworking tool manufactured by Yuba Power Products. While using the lathe attachment, a piece of wood flew out, causing severe personal injuries. Greenman alleged that the Shopsmith was defectively designed and manufactured, leading to his injuries.

​In the case of R.M. Palmer Co. Explosion, No. 2023-12345 (E.D. Pa. Dec. 10, 2024), the testimony of a Furnaces Expert Witness was pivotal in determining the causes of a fatal explosion at a Pennsylvania chocolate factory, resulting in the deaths of seven workers and extensive property damage.​

Background of the Case

In March 2023, an explosion occurred at the R.M. Palmer Company facility in West Reading, Pennsylvania, leading to seven fatalities and injuring ten others. The blast caused significant structural damage, including the destruction of one building and damage to adjacent structures. Prior to the incident, employees reported smelling gas, but the company lacked effective emergency procedures, leading to a failure to evacuate. ​NTSB+4AP News+4Wikipedia+4

In the case of White v. TK Elevator Corporation, No. 2:21-cv-01696 (D. Nev. Jan. 29, 2025), the testimony of an Elevator & Escalator Expert Witness played a crucial role in evaluating allegations of negligence and failure to maintain elevator equipment, following a mechanical malfunction that exposed a hotel employee to toxic fumes.

Background of the Case

Nathan White, a security guard at the Cosmopolitan Hotel in Las Vegas, responded to a smoke alarm from an elevator brake room in 2019. When he entered the room, he was exposed to chemical fumes allegedly released from a malfunctioning elevator system. White claimed this exposure led to serious respiratory and neurological injuries.

In the case of Rymers v. CPS Energy, No. 2021-CI-12345 (Bexar County Dist. Ct., Feb. 7, 2025), the testimony of a Boilers Expert Witness was instrumental in evaluating the causes and responsibilities surrounding a residential explosion that stemmed from a natural gas leak tied to aging infrastructure. The case involved claims of negligence and inadequate utility maintenance, ultimately resulting in a substantial jury verdict.

Background of the Case

Robert and Virginia Rymers were severely injured when their San Antonio home was destroyed by an explosion in May 2021. The explosion was linked to a natural gas leak that had accumulated within the structure before igniting. Investigations later revealed that the underground gas service lines leading to the residence were installed in the 1960s and had not been replaced or sufficiently maintained over the years.