This chapter introduces the reader to key cases analyzing claims of intellectual disability, describes the current clinical definition and diagnosis, and provides an overview of recurring issues in capital litigation. In 2002, the U.S. Supreme Court ruled that individuals with intellectual disability may not be executed. The Court subsequently clarified that current medical standards must be used in assessing claims of intellectual disability in capital cases. The clinical diagnosis requires assessing three factors: (a) deficits in intellectual functioning; (b) deficits in adaptive behavior; and (c) the onset of deficits during the developmental period. Courts must be informed by current medical standards regarding issues that arise, including the standard error of measurement in IQ scores, the problems of offsetting weaknesses in adaptive behavior with perceived strengths, and other clinical topics. The principle that the death penalty must not be imposed on individuals with intellectual disability signals important responsibilities for social work practitioners.
The association between WAIS subtests and adaptive behavior in mental retardation and borderline intellectual functioning: evidence for ecological validity