Opinion of the Court
As discussed above, clinical definitions of mental retardation require not only subaverage intellectual functioning, but also significant limitations in adaptive skills such as communication, self-care, and self-direction that became manifest before age 18. Mentally retarded persons frequently know the difference between right and wrong and are competent to stand trial. Because of their impairments, however, by definition they have diminished capacities to understand and process information, to communicate, to abstract from mistakes and learn from experience, to engage in logical reasoning, to control impulses, and to understand the reactions of others.23 There is no evidence that they are more likely to engage in criminal conduct than others, but there is abundant evidence that they often act on impulse rather than pursuant to a premeditated plan, and that in group settings they are followers rather than leaders.24 Their deficiencies do not warrant an exemption from criminal sanctions, but they do diminish their personal culpability.
In light of these deficiencies, our death penalty jurisprudence provides two reasons consistent with the legislative consensus that the mentally retarded should be categorically excluded from execution. First, there is a serious question as to whether either justification that we have recognized as
23 J. McGee & F. Menolascino, The Evaluation of Defendants with Mental Retardation in the Criminal Justice System, in The Criminal Justice System and Mental Retardation 55, 58-60 (R. Conley, R. Luckasson, & G. Bouthilet eds. 1992); Appelbaum & Appelbaum, Criminal-Justice Related Competencies in Defendants with Mental Retardation, 14 J. of Psychiatry & L. 483, 487-489 (Winter 1994).
24 See, e. g., Ellis & Luckasson, Mentally Retarded Criminal Defendants, 53 Geo. Wash. L. Rev. 414, 429 (1985); Levy-Shiff, Kedem, & Sevillia, Ego Identity in Mentally Retarded Adolescents, 94 Am. J. Mental Retardation 541, 547 (1990); Whitman, Self Regulation and Mental Retardation, 94 Am. J. Mental Retardation 347, 360 (1990); Everington & Fulero, Competence to Confess: Measuring Understanding and Suggestibility of Defendants with Mental Retardation, 37 Mental Retardation 212, 212-213, 535 (1999) (hereinafter Everington & Fulero).Page: Index Previous 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Next
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