Although the U.S. Supreme Court has determined that the intellectually disabiled (mentally retarded) are barred from the death penalty, the decision of whether a defendant meets this disability standard is not made by mental health experts but by jurors and judges. A recent study published in Law & Psychology Review found that jurors expect a much lower level of intellectual functioning than mental health experts to arrive at a finding of disability. Moreover, jurors are persuaded away from a disability finding by statements that the defendant knew his actions were wrong—even though such knowledge should not disqualify someone from being intellectually disabled. The study concluded that “jury pool members were less likely than experienced mental health workers to see severe impairments in functioning as evidence” of an intellectual disability. The implication of these findings is that fact finders are likely to fail to identify defendants with more moderate intellectual disabilities, even when impairments clearly meet diagnostic criteria used by mental heath professionals. Read full study.

(M. Boccaccini, et al., “Jury Pool Members’ Beliefs About the Relation Between Potential Impairments in Functioning and Mental Retardation,” 34 Law and Psychology Review 1, 21 (2010)). See Studies on the death penalty and Intellectual Disability.