According to the U.S. Supreme Court, capital punishment is constitutional and is not cruel and unusual punishment as long as proper procedures are followed and the punishment comports with "evolving standards of human decency." Special consideration, however, must be given to mentally retarded offenders. These offenders have traditionally been ill-treated by the criminal justice system because that system fails to recognize and defer their substantial mental defects. Insane and juvenile offenders are accorded a great deal of consideration because their "defects," i.e., mental illness or youth, may lessen or negate their criminal culpability. Retarded individuals possess characteristics similar to those of the insane and the young, and the same arguments used to prohibit the execution of these two groups or to mitigate their sentences can be successfully applied to mentally retarded individuals. Courts and attorneys, however, must recognize that a retarded offender's capacity cannot be measured by the same standards as those used to determine exculpatory insanity or youthfulness. Recognizing that mental retardation is not a mental illness, mental retardation must be measured by standards designed to determine the extent of retardation (mental age of offenders and their capacity to determine and understand the consequences of their actions). In the case of the mentally retarded, the death penalty may represent legal but unjustified murder. 337 footnotes