Of the eight States creating the guilty but mentally ill verdict, only Illinois and New Mexico failed to provide an unequivocal statutory right to treatment. This verdict was largely a response to alleged inadequacies in procedures for committing and releasing defendants found not guilty by reason of insanity. The 1981 Illinois law places the treatment decision wholly in the discretion of the Department of Corrections (DOC), increasing the likelihood that only very severe cases will receive any treatment. In contrast, Michigan's 1976 guilty but mentally ill statute provides a substantial statutory right to treatment which the State courts have recognized. While these decisions have had a positive effect on treatment facilities in Michigan's correctional facilities, prison mental health services are still inadequate. Under the current standard, promulgated in Estelle v. Gamble, it is extremely difficult to establish an individual eighth amendment claim for lack of mental health treatment. Courts have upheld inmates' rights to psychological or psychiatric treatment, but the Illinois statute which requires an evaluation and any treatment deemed necessary by the DOC probably meets the eighth amendment's threshold requirements. On the other hand, current interpretation of the 14th amendment lends itself to a much stronger right to treatment, because a long line of cases have ruled this amendment mandates treatment of civilly committed mental patients, sexual psychopaths, and juvenile offenders. However, no such claim has yet been litigated in the State or Federal courts. The paper includes 174 footnotes.