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The problem with probability: here's how to spot when defense experts misuse probability in your auto case, and what to do about it.

Article Excerpt
Probability forms a basis for many decisions people make. When you buy a new DVD player and opt not to purchase the extended warrantee for an additional $30, you are evaluating, consciously or subconsciously, a series of probabilities. Many factors--how much the unit costs, your prior experience with DVD player failure, and how long you usually keep electronics before replacing them with an updated model--affect your decision that it is less than likely that the $30 expenditure is justified.

Probability plays a pervasive, important, and typically hidden role in virtually every auto injury case. Both plaintiff and defense experts rely extensively on probability or risk (used synonymously in this article) to persuade a judge or jury that their opinions are valid. These opinions affect how the fact-finder perceives issues--such as causation, negligence, and injury severity and prognosis--that dictate trial outcomes.

Unsubstantiated probabilities are often used to bolster weak or completely unsupported expert testimony. Contrary to some trial lawyers' beliefs and practices, testimony that improperly relies on probability does not become more valid when offered on behalf of an injured plaintiff.

MIST v. MAID

The defense's use of probability in minor impact/soft tissue (MIST) cases differs from its use in major auto injury and death (MAID) cases in several ways. The defense uses probability after the fact to deny causality in MIST cases. For example, an expert will say it is within the realm of possibility that a plaintiff who developed neck pain within a day of a minor collision, or felt arm pain within a week, or was diagnosed with a herniated cervical disc within a month had these symptoms before the collision, was injured some other way, or is not really injured. This allows the defendant to ask the jury to speculate about some other, unnamed injury cause.

In contrast, the defense cannot claim that a plaintiff who has been catastrophically injured or killed in a high-speed collision was paralyzed or dead before the collision or was injured in some other way shortly afterward. In MAID cases, the defense must account for the injury while pointing to a higher probability that the failure to wear a seat belt or the...