Chauhan, P., Warren, J., Kois, L., & Well-beloved-Stone, J. (2015). Psychology, Public Policy and Law, 21, 1, 56-59.
This study examined the impact of conjoint CST and MSO evaluations on forensic examiner opinions. Readers are undoubtedly aware that contextual information may have a significant influence on examiner decision-making especially under conditions of uncertainty. The authors examined 5,731 evaluations conducted over a 17-year span. They note that conjoint evaluations may be common (44 to 63%). The study did not include Hawaii where the great majority of court-ordered examinations are conjoint CST-MSO (estimated 85% in my experience).
The authors note that CST and MSO examinations are distinctly different. While these examinations are a commonplace, ethical and methodological issues in conjoint evaluations have not been examined.
The findings indicated that opinion findings differed as a function of the type of examination (CST vs MSO vs CST/MSO). If a defendant was opined incompetent, an opinion of insanity was more likely than an opinion of sanity. They note, not surprisingly that the predictors of CST and MSO are significantly different. They note significant differences in structure between types of examinations, that an insanity opinion was more likely within the joint versus MSO-only evaluation. “Joint evaluations were less likely to lead to an opinion supportive of incompetency but more likely to lead to an opinion supportive of insanity” (p. 59). They suggest that CST may be more influenced by MSO opinions than the converse.
They raise the issue of whether a non-CST defendant may be competent to consent to an evaluation. They note that “evaluators should not proceed with an evaluation of MSO if the defendant is incompetent, but these data suggest that they often do” (p. 56). They conclude that “significant and potentially opinion-impacting differences arose from the decision to evaluate competency and sanity singularly or jointly” (p. 59).
The basis for single versus conjoint evaluations from the point of view of attorneys and judges is unknown. Are these evaluations driven by economics (cost of evaluations?) versus legal strategy? In my private forensic consultation work, I note that bifurcation of the exams is more common than publicly funded evaluations. Clearly, more work needs to be done to clarify these issues.