How Criminal Law Exploits Jury Ignorance

At the end of criminal trials in which the defendants’ mental state is at issue, American juries traditionally had three verdict options: guilty, not guilty, and not guilty by reason of insanity (NGRI). More recently, several U.S. states enacted statutes that added a new verdict option: guilty but mentally ill (GBMI). GBMI verdicts are intended to hold defendants with mental illness criminally responsible while ostensibly promising psychiatric care for their mental illness in prison. Unfortunately, in practice, GBMI statutes do not provide defendants meaningful access to mental health treatment, and GBMI verdicts result in prison sentences that are no different than those for guilty defendants. However, because jurors are mostly unaware of the sentencing consequences of GBMI verdicts, scholars have debated whether jurors render GBMI verdicts based on the false speculation that GBMI defendants will receive a reduced sentence or guaranteed access to psychiatric treatment, rather than the evidence presented at trial. <br><br>In this paper, I first provide empirical evidence from mock jury trials that the availability of the GBMI verdict option significantly reduces the frequency of NGRI verdicts in favor of GBMI verdicts, even when the evidence presented at trial supports an NGRI verdict, largely because jurors misunderstand and speculate about the sentencing consequences of the two verdict options. Second, I show empirically that plain-language jury instructions may decrease the frequency of unwarranted GBMI verdicts by better informing jurors about the sentencing consequences.<br><br>Overall, my findings indicate that many jury verdicts may be a product of jury ignorance, rather than a careful consideration of the evidence presented at trial. And if criminal jury verdicts are to better reflect the weight of the trial evidence, then verdict options should be accompanied by plain-language jury instructions on sentencing consequences.