Judicial Notebook

With forensics-based TV shows like "CSI," "Law and Order," "Crossing Jordan" and "Forensic Files" dominating the Nielson ratings, Americans are bombarded with fictional accounts of the American criminal justice system's inner workings and the manner in which investigators collect, analyze and interpret crime scene evidence. Does exposure to fictionalized legal procedures alter viewers' expectations of legal evidence, and would such expectations influence their evaluations of an actual legal case should they be chosen to sit on a real jury?

A great deal of media attention has focused on the "CSI Effect," a phenomenon in which popular TV shows are thought to raise jurors' expectations about forensic science, particularly crime scene investigation and DNA testing. According to anecdotal media reports, these expectations do more harm than good. Prosecutors who fail to present an exhaustive case may experience a backlash from jurors who expect large quantities of evidence, even when the evidence is nonexistent, inconclusive or irrelevant to the case. Defendants are similarly at risk from the expectations of TV-savvy jurors, with attorneys concerned that jurors give too much weight to prosecution evidence, regardless of its validity.

A case in point

In State v. Cooke (914 A.2d 1078), 2007, the Delaware Supreme Court examined the CSI Effect. After being indicted for the murder of a local college student, Cooke filed a series of motions to exclude 10 pieces of prosecution evidence, including analyses of footwear impressions, voice identification, handwriting, fiber, DNA, fabric impressions, hair, video, toolmarks and trace. Cooke argued that tests for each piece of evidence were either inconclusive or exculpatory, and he challenged their relevance.

In response, the prosecution claimed the tests were necessary to demonstrate to jurors that it had conducted a thorough criminal investigation. Noting widespread media coverage of criminal trials and the prevalence of forensic-based TV shows, the prosecution further argued that it needed to produce enough evidence to address jurors' heightened expectations regarding what the prosecution must do or show in order to meet its burden of proof. After reviewing the literature on the CSI Effect, the court thought it naíve to think the effect did not exist, as the court had witnessed first-hand defendants taking advantage of absent prosecution evidence. However, the court found only two academic opinions related to the CSI Effect, neither of which validated the phenomenon.

Although refusing to rule on the legitimacy of the effect, the court noted that the defendant's argument put the prosecution in a "Catch 22" conundrum in that the prosecution could be criticized for either proffering too much irrelevant evidence or not presenting enough evidence. Rather than limit the prosecution's ability to thoroughly state its case, the court found little harm in allowing the presentation of inconclusive evidence, though it did acknowledge the need to subject all scientific tests to the admissibility standards set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc. (509 U.S. 579, 125 L. Ed. 2d 469, 113 S. Ct. 2786, 1993, which governs the admissibility of expert testimony) and Kumho Tire Co. v. Carmichael (119 S. Ct. 1167, 1999, which grants the judge the status of gatekeeper for deciding whether evidence is reliable).

More research needed

Although the court relied on some academic work in its decision, little is known about the CSI Effect, and preliminary research on the existence and direction of the effect has produced mixed results. Some studies have failed to observe the effect among students participating in mock-jury simulations, though other studies have found support for the prosecution version of the CSI Effect with nonstudent samples. In one study, nonstudent mock jurors who watched more "CSI"-like TV programs had higher expectations for the amount of forensic evidence necessary to prove the defendant's guilt, and they were less likely to find culpability. Other studies found evidence for the defense version of the CSI Effect, with mock jurors who thought "CSI" and similar programs were believable overvaluing forensic evidence and returning guilty verdicts when presented with any DNA evidence, be it good or poor quality. In light of the limited and mixed empirical findings, future research is necessary before any definitive claims can be made about the existence and veracity of the CSI Effect. Of particular interest is determining the conditions in which the CSI Effect exerts an influence on jurors' decisions. It is possible, for example, that such effects only occur in homicide cases, which are among the most prevalent crimes on forensic shows, though the CSI Effect may also vary depending on the amount and quality of evidence.

Judicial Notebook is a project of APA's Div. 9 (Society for the Psychological Study of Social Issues).