South-Western Legal Studies in Business

Defective Expert Testimony Results in Reversal of Verdict

Texas high court held that a jury verdict about tire failure caused by a production defect could not stand as it was based on unreliable expert testimony. The testimony was speculation as it was the opinion of the witness. There was no scientific evidence or theory to back up the conclusions of the witness.

Topic Court Procedure
Key Words

Evidence; Expert Testimony; Reliability; Product Defect

C A S E   S U M M A R Y

Mendez was driving a minivan with six passengers when a rear tire made by Cooper Tire lost its tread. Mendez lost control and rolled the minivan. Four passengers were killed. Mendez and two others survived. Examination of the tire showed that a nail had punctured it. The survivors sued Cooper for product defect. A jury awarded over $11 million in damages; the appeals court affirmed. Cooper appealed.


Reversed. Grogan provided expert testimony for plaintiffs. His theory was that the tire failed because it was contaminated with wax at the plant, causing the steel belts to separate from the tire. Expert testimony is admissible if the expert is qualified, the testimony is relevant, and it is based on a reliable foundation. Grogan is a high school graduate who worked at a tire factory in England. For two decades, since he moved to the U.S., he has lectured about tire failure and published a book and some articles on tire failure. He contended the fact that a nail punctured the tire, that the car was overloaded, and that the tire was under-inflated made no difference, the problem was contamination during production. His testimony on that theory was unreliable and should have been excluded. His only source for that theory was his own book, which was not peer reviewed. He had no other source of support for his testimony-no physical evidence, no records, no scientific discussion of this issue in other publications. His evidence was mere speculation, but was the primary basis of the verdict, so it cannot stand.


Cooper Tire & Rubber v. Mendez, ---S.W.3d--- (2006 WL 1652234, Sup. Ct., Tx., 2006)

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