Question: In an exposure case, can an expert base their opinion on a mere temporal coincidence of the exposure and the plaintiff’s illness?
Answer: No, see below.
When faced with a proffer of expert scientific testimony, the court must make a preliminary assessment of whether the reasoning or methodology underlying the testimony is scientifically valid and whether that reasoning or methodology properly can be applied to the facts in issue. Scientific knowledge admissible connotes more than subjective belief or unsupported speculation. This court has explained: “Pseudoscientific conjectures that are probably wrong are of little use in the project of reaching a quick, final, and binding legal judgment.” Moreover, to be admissible, an expert’s opinion that an event caused a particular injury must be based on something more than coincidence. Thus, expert testimony must be supported by appropriate validation or good grounds based on what is known, establishing a standard of evidentiary reliability. A mere temporal coincidence between exposure and plaintiff’s illness is insufficient to establish a prima facie case.