Who is an expert? Competency evaluations in mental retardation and borderline intelligence.

Evaluations of competency to stand trial (CST) in defendants with mental retardation or borderline intellectual functioning can be difficult when deficits are masked by the type of adaptations seen in many with developmental disabilities. Accordingly, many evaluators have used validated test instruments, such as the CAST*MR (Competence Assessment to Stand Trial for Defendants with Mental Retardation) and tests measuring receptive and expressive language, to augment the clinical interview. The authors present a New Jersey case illustrating the need for clinicians to have adequate experience and training in some of the less known psychometric tests before presenting evidence in court. At the CST hearing, the judge disregarded the testimony of several psychologists while accepting that of a less experienced state's expert, we believe, to find the defendant competent. The finding was reversed on appeal. We encourage forensic professionals to be aware of the various instruments and minimum standards when employing specialized testing.