"Reasonable medical certainty": can we meet Daubert standards in insanity cases?

When mental health professionals testify in insanity defense cases (more generally, about mental state at the time of the offense [MSO]), opinion testimony is generally solicited after the prefatory question as to whether the forthcoming opinions are held with “reasonable medical certainty” (psychiatrists) or “reasonable scientific certainty” (nonmedical experts). The question and its answer—almost inevitably a “Yes”—are a virtual mantra with which most readers of this Journal are probably quite familiar. In this brief editorial, I discuss what can, arguably should, and in the worst (or perhaps, best) case scenario, may have to be done in light of evolving standards for admissibility of expert testimony. Prior to Daubert v. Merrell Dow Pharmaceuticals Inc. expert testimony was generally governed by the “general acceptance” test established under Frye v. U.S. As Frye was generally applied, expert witnesses were on safe ground so long as they had employed methods generally accepted in their field for gathering the information on which their opinions were based. As Simon noted, “Daubert shifted the focus from the general acceptance of the conclusion of expert testimony to the underlying reasonableness or soundness of the methodology” (Ref. 3, p 4). With its emphasis on (along with “acceptability”) the testability of scientific knowledge, peer review, and publication history and factors affecting potential error rates, Daubert directed trial judges to evaluate the potential validity of experts’ methods, not merely their acceptability. In the context of MSO evaluations, this is a rough gauntlet thrown in the face of the mental health professions. Simon noted further, “A standard methodology for the retrospective determination of an individual’s mental state does not exist . . .[and that]. . .good validity studies [of MSO evaluations] are practically nonexistent” (citation omitted) (Ref. 3, p 5). Accepting Simon’s disturbing, but I think accurate, appraisal of the current state of affairs, one wonders what expert witnesses in Daubert jurisdictions might be thinking in claiming, willy-nilly, “reasonable medical/scientific certainty” in MSO cases (but see Poythress, for what may happen if they answer otherwise).