The Mentally Disordered Criminal Defendant at the Supreme Court: A Decade in Review

The cases discussed in this Article concern three general topics: the culpability of juvenile offenders; mental states and the criminal process, including the presentation of mental disorder evidence, competency to stand trial, and competency to be executed; and the preventive detention of convicted sex offenders. Part I examines two cases that adopted categorical exclusions from certain kinds of punishment—the death penalty and life without parole—for juvenile offenders, based on the diminished culpability of juveniles as compared to adult offenders. Both of these cases built on a third recent case, which categorically excluded people with mental retardation from the death penalty. In all three of these cases, the Court overrelied on the results of psychological studies to justify its legal conclusions. Part II discusses three cases involving questions about mental states. The Court misunderstood the relevant psychology in two of these cases. In one case, the misunderstanding led the Court to uphold a state law prohibiting criminal defendants from presenting mental illness evidence to raise reasonable doubt about mens rea. In the second case, the Court adopted a nearly limitless test for determining when the government may administer involuntary antipsychotic medications for the purpose of rendering a criminal defendant competent to stand trial. The Court demonstrated a more complete understanding of the relevant psychology in the third case, recognizing that delusional beliefs can preclude a convicted prisoner’s understanding of the state’s reasons for carrying out a death sentence. Part III considers two cases involving the question whether the preventive detention of convicted sex offenders is really civil commitment, as states have claimed, or is instead criminal punishment, as its critics have claimed. Among the issues raised in these cases are the legal primacy of diagnoses recognized by psychiatrists and the moral justification for the civil commitment of people who are dangerous because of a mental disorder