Product Defect

The distinction often requires comparing the failed product with its intended design. Drawings, specifications, tolerances, materials, production records, measurements, testing, and exemplar products can show whether the item conforms to the intended configuration or contains a production-related deviation. A design issue instead concerns characteristics inherent in the intended product. The governing legal tests vary by jurisdiction, so the expert's technical analysis should be distinguished from the determination of whether the applicable legal standard for defect has been satisfied.

Photographs, videos, inspection notes, drawings, specifications, manufacturing and quality records, laboratory results, repair records, incident documentation, and exemplar products may still provide useful evidence. An expert should also identify limitations created by the absence of the original product because photographs or exemplars may not preserve conditions that could have been observed through a physical inspection.

Testing may be appropriate when the dispute involves material properties, dimensions, strength, electrical performance, chemical composition, component behavior, or whether a suspected failure condition can be reproduced. Depending on the product, techniques can range from dimensional measurements and nondestructive examination to microscopy, material testing, or controlled performance tests. Destructive testing should be planned carefully with counsel because it permanently changes the evidence being examined.