The diminished capacity rule was nurtured in California. In one form or another, it has been adopted in approximately one-third of the States, mainly in cases in which the defendant is charged with first-degree murder. Under the diminished capacity doctrine, a criminal defendant may introduce evidence of mental abnormality to negate the mental element of the crime charged, thereby exonerating the defendant of that charge. The evidence of diminished capacity, although not quite meeting the standard for "not guilty by reason of insanity," may warrant a verdict of manslaughter instead of murder. The States that have not adopted the diminished capacity rule hold that mental capacity is all or nothing and that only insanity, by whatever definition, negates criminal intent. California has abolished the diminished capacity defense, marking a trend away from its use. Still, the concept is not totally dead. In the pretrial stage, the diminished capacity concept influences the prosecutorial decision about what charge to bring. Given current public concern about crime, the immediate future appears less conducive to defenses that lessen criminal responsibility for harms done. 86 notes