The Daubert Challenge
Kumho Tire v Carmichael:
The Expert’s Conclusion (Part V)

Parts I-IV of our series of e-zines on the Daubert Challenge are available at our website http://www.warren-group.com/archives.html .

Expert Carlson’s conclusion that the defect existed rested on certain propositions, several of which the defendants strongly disputed.

1. Carlson said that if a separation is not caused by a certain kind of tire misuse, called “over-deflection,” which consists of under-inflating the tire or causing it to carry too much weight, thereby generating heat that can undo the chemical tread/carcass bond, then, ordinarily it is a defect.
2. He said that if a tire has been subject to sufficient over-deflection to cause a separation, it should reveal certain physical symptoms or physical signs. These physical signs include:
   • (1) tread wear on the tire’s shoulder that is greater than the tread wear along the tire’s center,
   • (2) signs of a bead groove where the beads have been pushed too hard along the bead seat on the inside of the tire’s rim,
   • (3) sidewalls of the tire with physical signs of deterioration, such as discoloration
   • (4)and/or marks on the tire’s rim flange.
3. Carlson said that where he does not find at least two of the four physical signs just mentioned, he concludes that a manufacturing or design defect caused the separation.

Carlson inspected the tire and conceded that the tire, to a limited degree, showed greater wear on the shoulder than in the center, some signs of bead groove, some discoloration, a few marks on the rim flange and inadequately filled puncture holes which can also cause heat that might lead to separation. But in each case, he testified that the symptoms were not significant, and he explained why he believed they did not reveal over-deflection.

For example, the extra shoulder wear, he said, appeared primarily on one shoulder, whereas an over-deflected tire would reveal equally abnormal wear on both shoulders. Carlson concluded the tire did not bear at least two of the four over-deflection symptoms, nor was there any less obvious cause of separation, and since neither over-deflection nor the punctures caused the blowout, a defect must have done so.

In 1999, the Supreme Court addressed these issues in Kumho Tire v. Carmichael. The court indicated that the trial judge’s “gate keeping obligation” applies not only to scientific knowledge, but also to testimony based on “technical” and “other specialized” knowledge. In other words, Kumho Tire applies to the testimony of engineers.

The ruling did go on to state that the Court may consider one or more special factors mentioned in Daubert to determine testimony’s reliability, which is the test of reliability is flexible. Additionally, the Daubert list of reliability factors should not be exclusively or applied to all experts or in every case.