Uncovering the Root Cause: Forensic Engineering in Product Liability Cases

Product liability litigation has undergone a significant transformation over the past century. Originally grounded in caveat emptor—“let the buyer beware”—early cases offered little recourse to injured consumers unless a direct contractual relationship existed between buyer and seller. Landmark decisions such as MacPherson v. Buick Motor Co. and Greenman v. Yuba Power Products expanded the scope of liability by recognizing that manufacturers owed a duty of care that extended beyond privity. Today, product liability claims often rest on strict liability, shifting the focus away from the manufacturer’s conduct and toward whether the product itself was unreasonably dangerous.

Against this legal backdrop, forensic engineering plays a critical role in determining the root cause of alleged defects and providing objective findings that legal teams can rely on. Whether the claim involves strict liability, negligence, or breach of warranty, the need for clear, fact-based answers is universal. Through representative case studies in this guide, we highlight the value of engineering insight grounded in physical evidence, industry standards, and scientific methodology.

The Role of Forensic Engineering in Legal Cases

At EDT, we apply engineering principles to investigate failures, assess damages, and identify root causes. Our engineers are involved in a broad range of product liability cases, providing:

• Forensic analysis to determine cause, scope, and contributing factors
• Evaluation of design and manufacturing processes
• Assessment of usage, warnings, and foreseeable misuses
• Support for litigation strategy through expert opinions and documentation

Our findings are always objective. Attorneys use our reports to inform decisions—whether that means pursuing a claim, supporting a defense, or closing a file with confidence.

The Exploding Circular Saw

Incident Overview

A homeowner sustained injuries while using a circular saw purchased at a national hardware chain. The saw functioned properly during several cuts—until the last cut, when the user pulled the trigger and the tool failed to start. Moments later, the housing ruptured, sending pieces of plastic outward.

Investigation Process

EDT was retained to lead the forensic investigation. Our team coordinated a joint exam with stakeholders, carefully disassembled the failed unit, and acquired an exemplar saw of the same make and model to compare components.

Findings

The saw’s design included a lock plate that engaged with machined flats on the motor shaft to assist with blade changes. A spring was intended to disengage the plate during normal operation. In this case, the spring was never installed. With the shaft inadvertently locked in place, torque transferred to the plastic housing, leading to rupture.

“This incident underscores the critical need for timely, thorough forensic analysis. Our investigation revealed a missing spring—never installed during assembly—as the root cause. It wasn’t a defect you could see. But it changed everything.” EDT Consulting Engineer

Conclusion

The failure resulted from a manufacturing oversight: the spring had not been installed during assembly. Based on the saw’s design, EDT concluded the spring could not have dislodged during regular use.

Heated Car Seat Burns

Incident Overview

An individual operating a vehicle equipped with climate-controlled seats sustained thermal injuries. The seat was part of a luxury vehicle package that included adjustable heating levels.

Engineering Involvement

EDT engineers were asked to evaluate the seat heater’s function and controls. Testing involved thermographic imaging and thermal sensor analysis during repeated operation cycles.

Findings

Temperature readings exceeded 140°F in certain scenarios. The measured seat temperatures surpassed the manufacturer’s maximum allowable threshold, indicating a design defect. 

“Engineering tests showed seat heaters in some vehicles reached up to 150°F—without automatic regulation or clear warnings for users with impaired thermal sensation.” — Excerpt from USA Today coverage on seat heater safety concerns

Conclusion

The engineering assessment identified elevated surface temperatures under foreseeable conditions, which exceeded the manufacturer’s maximum allowable surface temperature.

Tools Engineers Use to Support Legal Strategy

Attorneys working with forensic engineers benefit from a wide range of technical support services, including:

• Physical and digital failure reconstruction
• Materials testing and non-destructive evaluation
• Review of technical documentation and compliance standards
• Identification of deviation from design specifications
• Comparative analysis using exemplar products
• Clear, accessible reporting for use in mediation or court proceedings

EDT engineers are frequently asked to participate in joint exams, offer second opinions, and serve as expert witnesses. Our documentation is thorough and prepared to withstand scrutiny.

Legal Doctrines That Forensic Engineering Supports

Negligence

Engineers help determine whether a defect was detectable through reasonable inspection—and whether the producer exercised due care.

Strict Liability

In many jurisdictions, strict liability applies even without proof of negligence. Engineers help establish whether the product was unreasonably dangerous and whether the defect was present when the product left the producer’s control.

Breach of Warranty

Express and implied warranties are common in product advertising. Engineers can assess whether product performance aligned with those representations.

Misuse and Modification 

In cases involving altered products, engineering analysis helps determine whether the misuse or modification was reasonably foreseeable.

The Value of Objective Forensic Analysis

EDT’s role is to uncover the technical truth—objectively, thoroughly, and clearly. We don’t advocate for one side or the other. Instead, we apply sound engineering practices to provide accurate, defensible findings that support legal decision-making. Our reports reflect the highest standards of professionalism and ethics, and our engineers are prepared to explain those findings clearly, whether in deposition or trial.

Whether you're managing a complex case involving machinery, consumer products, or electronic components, EDT’s experienced engineers are here to help.

We bring unmatched forensic expertise, a hands-on practical approach, and a commitment to clear, objective reporting.

Why Legal Clients Choose EDT

• Courtroom-tested engineers with decades of deposition and trial experience
• Unbiased findings that hold up under cross-examination
• Support for design defect and product liability cases through thorough investigation, testing, and visual demonstratives

When the outcome matters, it helps to have an engineer who knows the legal process inside and out. Find an expert today.

About the Author

Kyle T. Minden, P.E. is a consulting engineer with our Kansas City, MO office. Mr. Minden provides consulting services in the areas of design and performance of machinery and machine components, pressure vessels, fracture analysis, metallurgy, fire protection sprinkler systems, materials, and component testing, and infrared thermography. You may contact Kyle for your forensic engineering needs at kminden@edtkc.com or (913) 449-4953.