Michigan v. Tyson

Brief filed: 4/23
Court: Michigan Supreme Court
Year of Decision: 2023

Read full-text amicus brief (PDF, 301KB)opens in new window

Whether the Michigan Supreme Court reinstate the defense of diminished capacity and overrule its decision in Carpenter?

Insanity Defense/Diminished Capacity

Jacquelyne Tyson was convicted on one count each of first- and second-degree murder and two counts of felony firearm possession and sentenced to life imprisonment without the possibility of parole, life imprisonment, and two consecutive years in prison, respectively. Owing to her mental illness, Tyson believed she was the target of a conspiracy, which involved complex delusions including the presence of poisonous gas being pumped into her apartment and the atmosphere around her. Tyson’s two victims were employees of the apartment complex where she lived and she believed they were responsible for the toxins being pumped into her apartment. On the day of the crime, Tyson entered the main office of the apartment complex and opened fire, killing the first victim, then moments later entered a second room, where she shot and killed the second victim. She then left the office, walked 50-60 feet away from the building and sat down on the curb of the street until an officer arrived. Tyson was initially found not competent to stand trial and was committed to the Center for Forensic Psychology (Center), where it took two years for her competency to be restored. Attempting to prove legal insanity, the defense called her treating psychiatrist and forensic psychologist, both considered experts in the field, from the Center. Both defense experts testified that Tyson was legally insane at the time the crime was committed. The prosecution’s expert testified that, while mentally ill, Tyson was not legally insane. The trial judge found the experts to be equally credible but held that the facts better supported a finding that she was legally sane and delivered a verdict of Guilty But Mentally Ill (GBMI). On appeal, Tyson argued that a defense of diminished capacity, which the Michigan Supreme Court precluded in its decision in People v. Carpenter, 627 N.W.2d 276 (2001), should be available to the defendant to negate the intent element of the murder charges—namely, that due to her mental illness, she could not form the requisite intent needed to be found guilty of murder in the first degree, and thus could only be found guilty of a lesser offense. The Michigan Court of Appeals, adhering to court precedent in Carpenter, affirmed the trial court’s decision. The Michigan Supreme Court granted certiorari on the issue of whether to reinstate the defense of diminished capacity.

APA’s brief, joined by the Michigan Psychological Association and the National Association of Social Workers, argues in favor of reinstating the diminished capacity defense. The brief provides research on how certain mental health disorder symptoms can manifest in ways that would negate the ability for a person experiencing these symptoms to form the intent necessary to be found guilty of certain crimes and argues for making such evidence available to the trier of fact.

The Michigan Supreme Court denied the defendant’s application for leave to appeal the judgment of the Court of Appeals because the majority did not believe the questions presented should be reviewed by the Court. APA was represented by outside counsel at oral arguments before the Michigan Supreme Court and presented to, as well as answered questions from, several justices on the research cited in the brief. In addition, APA’s amicus brief was cited in Justice Cavanagh’s dissent to note that society’s understanding of mental illness and culpability has changed since the Court got rid of the diminished-capacity defense in its entirety in 2001.