Capital jurors, mental illness, and the unreliability principle: Can capital jurors comprehend and account for evidence of mental illness?

Abstract

Recent U.S. Supreme Court opinions have given rise to the question of whether persons suffering from a severe mental illness should be categorically exempt from the death penalty. This article presents a brief overview of relevant U.S. Supreme Court cases and the empirical evidence relevant to this question. We then present our findings on how actual capital jurors respond to and discuss engaging with evidence of mental illness, as drawn from in-depth interviews collected as part of the Capital Jury Project. Existing research reveals that in the controlled situation of an experiment, evidence of mental illness is associated with votes for life rather than death. Similarly, actual capital jurors in our study reported anticipating that evidence of mental illness would make them less likely to vote for death. However, those jurors who dealt with mental illness in their case appeared to be less sensitive: they describe such evidence as having been overshadowed by the brutality of the crime; as indicative of the defendant's future dangerousness; as being confusing, especially as presented by experts; and as a manipulative attempt on the part of the defendant to trick the jurors. The findings suggest that capital jurors cannot reliably comprehend and account for evidence of mental illness and thus offer a compelling reason for the Court to exempt those suffering from a mental illness from the death penalty.

The effects of witness mental illness and use of special measures in court on individual mock juror decision-making

“…More generally, this finding suggests that stigma towards individuals with mental illnesses still exists and can impact on decisions that people make about individuals. This is in line with previous research that has shown how merely labelling someone as having a mental illness can negatively impact perceptions of these individuals (e.g., Appelbaum & Scurich, 2014;Pescosolido et al, 1999;Sandys et al, 2018). 2 The authors also ran the full analyses without the inclusion of the 'attitudes towards mental illness' covariate.…”

“…In a review of archival data from court cases, Wolbransky (2011) found that jurors were more likely to assign harsher verdicts and recommend the death penalty to individuals who were described as mentally, or emotionally, "disturbed". Thus, when deliberating guilt, the defendant's diagnosis could be viewed as an aggravating factor, which increases culpability for the crime committed (Berryessa et al, 2015;Sandys et al, 2018).…”

“…Given the limited research in this area so far, it was unknown as to whether witness mental illness would directly impact on decisions about the guilt of the defendant. However, although somewhat mixed, previous research has tended to suggest that when deciding upon guilt, defendant mental illness could be seen as an aggravating factor which increases culpability of a crime (e.g., Berryessa et al, 2015;Sandys et al, 2018;Wolbransky, 2011) and in some cases can result in the wrongful conviction of an innocent person (Lamb & Weinberger, 1998). Despite the witness in the current study being assigned a mental illness rather than the defendant, the mere presence of mental illness as a factor in the courtroom could have impacted on decisions made.…”

Losing the lottery of life: Examining intuitions of desert toward the socially and genetically “unlucky” in criminal punishment contexts

“…Particularly, experimental work has generally established that social or genetic disadvantages can indeed attenuate support for capital punishment to varying degrees. For example, the mitigating effects of evidence on certain social disadvantages, such as abuse or history of poverty, have been weak or mixed with regard to affecting support for capital and other types of sentencing (Barnett et al., 2007; Berryessa, 2021; Tetterton & Brodsky, 2007; Monterosso et al., 2005; Najdowski et al., 2009; Stevenson et al., 2010), while some types of natural disadvantages, such as intellectual disability, mental illness, or physical abnormalities, have sometimes, but not always, shown stronger effects on mitigation support (Barnett et al., 2004; Berryessa, 2017, 2020; Boots et al., 2003; Edens et al., 2005; Greene & Cahill, 2012; Najdowski et al., 2009; Saks et al., 2014; Sandys et al., 2018). Yet other studies, and particularly those presenting an offender's genetic disadvantages, have shown little significant mitigating effects to death penalty sentencing (Appelbaum & Scurich, 2014; Appelbaum et al., 2015).…”