Prior to the Act's passage, the courts had relied upon one of two distinct tests of insanity, the M'Naghten test and the American Law Institute's (ALI) formulation, both of which provided offenders who suffered from either cognitive or volitional impairments with grounds for complete exculpation. The justification for abolishing the volitional test of nonresponsibility was the inability to distinguish scientifically those who are unable to resist criminal impulses from those who simply choose not to resist. This decision is contrary to historical precedent, constitutionally infirm, and impeachable from a policy perspective. The Act denies mentally impaired offenders the right to be held blameless for conduct that is beyond their power to control and leaves them defenseless against criminal accusations. 297 footnotes.