Effects of behavioral genetic evidence on perceptions of criminal responsibility and appropriate punishment.

Abstract

Demonstrations of a link between genetic variants and criminal behavior have stimulated increasing use of genetic evidence to reduce perceptions of defendants’ responsibility for criminal behavior and to mitigate punishment. However, because only limited data exist regarding the impact of such evidence on decision makers and the public at large, we recruited a representative sample of the U.S. adult population (n=960) for a web-based survey. Participants were presented with descriptions of three legal cases and were asked to: determine the length of incarceration for a convicted murderer; adjudicate an insanity defense; and decide whether a defendant should receive the death penalty. A fully crossed, between-participants, factorial design was used, varying the type of evidence (none, genetic, neuroimaging, both), heinousness of the crime, and past criminal record, with sentence or verdict as the primary outcome. Also assessed were participants’ apprehension of the defendant, belief in free will, political ideology, and genetic knowledge. Across all three cases, genetic evidence had no significant effects on outcomes. Neuroimaging data showed an inconsistent effect in one of the two cases in which it was introduced. In contrast, heinousness of the offense and past criminal record were strongly related to participants’ decisions. Moreover, participants’ beliefs about the controllability of criminal behavior and political orientations were significantly associated with their choices. Our findings suggest that neither hopes that genetic evidence will modify judgments of culpability and punishment nor fears about the impact of genetic evidence on decision makers are likely to come to fruition.

The blunt-edged sword: genetic explanations of misbehavior neither mitigate nor aggravate punishment

“…The introduction of genetic explanations for criminal behavior did not affect perceptions of culpability or sentences imposed by large, representative samples of the U.S. population presented with vignettes describing defendants who had committed serious offenses. 18 Moreover, a recent attempt by a German team, surveying 372 judges in that country, to replicate the findings noted above that evidence of a genetic predisposition to psychopathy led U.S. judges to select reduced sentences 19 was unsuccessful: using the same hypothetical vignette, the German researchers found that genetic evidence had no effect on the average length of the sentences selected. 20 Using somewhat different methods, Dar-Nimrod and colleagues found that evolutionary explanations of behavior related to sex (which are intrinsically genetic in nature) failed to impact subsequent decisions about bail and punishment for sex-related offenses in a set of hypothetical scenarios.…”

Judges’ views on evidence of genetic contributions to mental disorders in court

“…There has been far more research on how mock jurors or the U.S. public view this evidence (e.g. Appelbaum & Scurich, 2014; Appelbaum, Scurich, & Raad, 2015; Cheung & Heine, 2015; Scurich & Appelbaum, 2015). Concerning literature on judges specifically, a study in which U.S. state court judges were presented with evidence that an offender was genetically predisposed to psychopathy reported that the presentation of the evidence significantly reduced the severity of the judges’ sentences and the extent to which judges considered the offender’s disorder as an aggravating factor in sentencing (Aspinwall, Brown, & Tabery, 2012).…”

Behavioral Genetics in Criminal and Civil Courts

“…78,79 Yet no such finding emerged from American studies of representative samples of the general public, who were presented with genetic evidence (as well as a combination of genetic and neuroimaging evidence) in hypothetical capital and non-capital cases. 80,81 This remained true even when respondents were asked to consider a vignette involving a lesser offense (assault with a deadly weapon) 82 and when neurogenetic findings were introduced along with evidence of an interaction between a genetic propensity and child abuse 81,82 —a key finding in the literature on genetic predisposition to antisocial behavior and violence.…”

“…83 Some support for this view may be found in the studies of the general public: participants who were more skeptical about free will were more inclined to treat MAOA evidence as a mitigating factor. 80,82 Yet this position is at odds with other theories of justice that prioritize deterrence and incapacitation—the need to protect the general public by removing offenders from society—as purposes of criminal law.…”