25.7 Expert Witnesses

• Library: Virginia Construction Law Deskbook (Virginia CLE) (2019 Ed.)

25.7 EXPERT WITNESSES

25.701 Role of Experts in Establishing Causation. Expert testimony helps plaintiffs establish the causal connection between their exposure to a toxic substance and the injuries incurred as a result of that exposure. In a toxic mold case, for example, a team of experts may be useful in effectively establishing a sick building claim. ²¹² Industrial hygienists, contractors, architects, and structural engineers can determine the cause of a mold infestation, while immunologists, toxicologists, and neurologists can establish

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the adverse health effects of inhaling mold spores. ²¹³ A treating physician can also assist in establishing causation. ²¹⁴

When developing arguments to establish causation, it will likely be necessary to break it down into two analytical frameworks—general and specific causation. General causation refers to how the processes, mechanics, or substance "can" cause a mold or sick-building injury. Often general causation is established though a review of the accepted scientific and medical literature. ²¹⁵ The National Academy of Sciences (NAS) and the World Health Organization (WHO) have each published a leading treatise on the public health dangers and risks created by mold and "damp indoor space" sickness. ²¹⁶ These treatises provided some of the first widely accepted understanding of the immunological responses to, and consequences from, indoor mold exposure.

Specific causation helps to establish how an individual plaintiff has suffered. Often this is where a treating physician will provide the evidence necessary to show causation. ²¹⁷ A typical method applied in mold-related sickness is differential diagnosis. Under this approach, which is a widely accepted process within the medical community, possible causes of a patient's sickness are outlined and then eliminated until reaching one that cannot be ruled out or determining which cannot be excluded. ²¹⁸

25.702 Admissibility of Expert Testimony.

A. Virginia State Courts. Virginia state courts have taken a flexible approach to the admissibility of expert testimony. In Seneca Falls

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Greenhouse & Nursery v. Layton, ²¹⁹ for instance, the Virginia Court of Appeals ruled that the report of a neuropsychologist was sufficient evidence from which a commission could find that the claimant's panic attacks were directly caused by insecticide exposure even though the neuropsychologist was not a medical doctor. The fact that the neuropsychologist was not a medical doctor went only to the weight, not the admissibility, of her testimony. ²²⁰ In Hoffman v. Carter, ²²¹ the court held that where a claimant was exposed to plaster dust that allegedly caused him to suffer respiratory illness, a treating doctor's report indicating that the condition "certainly seems" to be caused by the plaster dust was definite enough to constitute evidence of causation by a preponderance of the evidence. ²²²

In Odaris v. Morton G. Thalhimer, Inc., ²²³ the Virginia Supreme Court, in an unpublished opinion, examined the trial court's decision to exclude an expert's testimony for lack of an adequate scientific basis. In this case, tenants sued their landlord/managing agent for personal injury and property damage due to mold exposure in their demised premises. At trial, an expert testified that the plaintiffs' exposure to mold caused their personal injuries. Following voir dire of the witness, the court, on the defendant's motion, excluded the expert's testimony. ²²⁴ On appeal, the Virginia Supreme Court reversed on this issue, holding that the admissibility of scientific evidence is not to be conditioned upon universal acceptance within the scientific community. ²²⁵ Rather, when unfamiliar scientific evidence is offered, and a trial court must determine whether to shield the jury from it, the court should not exclude such evidence where a sufficient foundation for its admission has been presented by the party proffering it. ²²⁶ A sufficient foundation was established where the expert, a physician, had an extensive clinical practice in the treatment of mold-related illnesses, was regularly consulted by others in the medical and scientific community in that regard, had published a number of peer-reviewed articles on the subject in recognized

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journals, and was not discredited with any contrary evidence presented by defendant. ²²⁷

B. Courts of Other States. State courts in...