Mechanical Engineering Expert’s Opinion on Alleged Manufacturing Defect in Accident Ladder Excluded
Posted on June 11, 2025 by Expert Witness Profiler
In this products liability action, Plaintiff Joshua Cleaveland sued Defendants Tricam Industries, Inc. and Home Depot USA Inc. after he fell from a Tricam model GLX-5B ladder on August 26, 2021. The ladder was manufactured by Tricam and purchased from Home Depot. According to Plaintiff, he was injured because the ladder was defective.
Defendants filed a motion to exclude the testimony of Plaintiff’s expert, Dr.
Jonathan Slocum.
Mechanical Engineering Expert Witness
Jonathan Slocum is a mechanical engineer who earned his bachelor’s degree in 2014, master’s degree in 2015, and doctorate in 2018 in mechanical engineering from the Massachusetts Institute of Technology.
He worked at Materials and Engineering Group LLC from 2017 to 2022 as a senior consultant, where he provided forensic and design consulting and failure analysis. Since 2020, his company LTAG Systems, LLC has been developing technology and devices for the United States Department of Defense.
Discussion by the Court
Defendants filed a motion to exclude Slocum’s expert testimony on the grounds that Slocum is not qualified to opine on ladder defects and design and causation, and his expert testimony is unreliable and speculative.
Initial Matters
The Court first addressed whether Plaintiff may rely on the First Slocum Affidavit to respond to Defendants’ motion to exclude.
The Court concluded that Plaintiff may offer the First Slocum Affidavit to defend the principles and methodology used by Slocum in his initial report.
To the extent that the Plaintiff attempted to use the First Slocum Affidavit to further explain Slocum’s qualifications as an expert in this case, the disclosure was untimely. Under Rule 26(a)(2)(B)(iv), Slocum was required to include all relevant qualifications in his initial expert report. As a result, the Court excluded certain parts of the First Slocum Affidavit.
Slocum’s Qualifications
The Court rejected Defendants’ argument that Slocum is unqualified to render an opinion in this case because he has never provided testimony specific to ladder design or accidents, has never designed a ladder or worked in the ladder industry, has no experience researching or addressing the causes of ladder-related accidents, and has never participated in any relevant committees that address ladder safety issues. While it is true that Slocum’s curriculum vitae indicated that he had little to no experience specific to ladder design and ladder-related accidents, his extensive education and professional background in mechanical engineering and metallurgy demonstrated that he is qualified to opine on whether the aluminum ladder in this case was defectively designed and manufactured.
Reliability of Slocum’s Testimony
First, the Plaintiff has failed to show that a simple visual inspection is a reliable methodology from which to draw conclusions about whether the ladder suffered from a manufacturing or design defect. While Slocum himself claimed, without proof, that his methodology is generally accepted in the “scientific community,” the Court cannot conclude that Slocum’s methodology is reliable because the Plaintiff has not put forth any evidence or argument that visual inspection alone is a reliable methodology for assessing the causes of ladder-related accidents.
Based on a visual examination of the accident ladder and the exemplar ladder and calculating the height/wall thickness ratio of the accident ladder’s rear rail, Slocum found “evidence of buckling at the pin joint” and “deformation of the aluminum tubing,” which he concluded to be a manufacturing defect that contributed to Plaintiff’s accident. However, Slocum provided no explanation or testing to demonstrate why the deformity at the “rear-left rail extrusion that the spreader-link pin-joint passes through” could be problematic.
Slocum concluded that the ladder was defective in design because he found that a “side load” is applied to the ladder’s front and rear rails when a user’s weight is on one of the top two steps of the ladder, leading to deformation of the ladder’s rails and spreader links. However, Slocum did not perform any tests to determine whether Plaintiff’s position on the top step of the ladder would lead to the buckling observed on the accident ladder or to prove that the spreader link of the ladder applied both an “eccentric load” and “torsion to the tube, which would add to the overall stress it experiences when loaded.” He also did not explain how much torsion or eccentric load is acceptable.
Held
The Court granted Defendants’ motion to exclude Dr. Jonathan Slocum’s opinion.
Key Takeaway:
Rule 702 does not require expertise to be so exacting. Although Slocum’s curriculum vitae shows minimal, if any, direct experience with ladder design or ladder-related accidents, his extensive education and professional background in mechanical engineering and metallurgy support his qualification to offer an opinion on whether the aluminum ladder in question was defectively designed or manufactured.
Case Details:
| Case Caption: | Cleaveland V. Home Depot United States Inc Et Al |
| Docket Number: | 3:23cv1298 |
| Court Name: | United States District Court, Connecticut |
| Order Date: | June 10, 2025 |
