Arizona, jurors in a murder trial voiced concern that a
bloody coat introduced as evidence had not been tested
for DNA, even though tests were not considered nec-
essary because the defendant had admitted being at the
murder scene. Some observers have attributed the
2005 acquittal of actor Robert Blake, charged with
murdering his wife, Bonnie Bakley, to the CSIeffect.
Even though the prosecutor presented more than 70
witnesses against Blake in this case, it is believed that
the jury wanted to see forensic evidence such as blood
splatter or gunpowder residue and found Blake not
guilty when such evidence was not presented. Attorneys
have even begun questioning potential jurors about
their viewing habits during voir dire and warning
jurors about the fictional nature of CSI.
The CSIeffect is most commonly defined as lead-
ing to a prodefense bias, as the above examples illus-
trate. In this sense, exposure to crime investigation
programming serves to raise jurors’ conviction thresh-
old, requiring more incriminating evidence to find
guilt. However, this effect can also be conceptualized
in another way. Some commentators note that crime
investigation programming enforces the belief that
forensic science is infallible and can provide defini-
tive evidence of guilt. Adherence to this belief would
actually work forthe prosecution, leading to more
convictions when any type of forensic evidence is pre-
sented, regardless of quality. In this way, crime inves-
tigation programming may actually lower jurors’
conviction threshold, requiring less incriminating evi-
dence to find guilt.
To date, little empirical research has examined the
impact of crime investigation programming on jurors’
verdicts and case perceptions. The little research that
does exist, consisting of a few law reviews and confer-
ence presentations, typically examines this effect by
measuring mock jurors’ exposure to crime investiga-
tive programming (e.g., hours per week) and having
them read through a case summary and answer vari-
ous questions about the case, including verdict.
The results of these preliminary studies are mixed,
but most suggest that watching crime investigation
programming does not influence verdict. In three
studies, mock jurors who report watching CSIa lot
were no less (or more) likely to find a defendant guilty
than are mock jurors who watch little or no CSI.
However, one study did find the predicted prodefense
effect, such that more hours of TV watching was
related to a perception of less strength in the prosecu-
tion’s case, which was related to more acquittals.
Also, most studies have found that the more a mockjuror finds the shows to be believable and realistic, the
more likely the juror is to favor the prosecution and
find the defendant guilty. Thus, whether jurors believe
the shows are realistic may be a better predictor of
decisions than how much the juror watches the shows.
Finally, there is also some suggestion that prosecu-
tion’s warning against CSI-caliber evidence may pro-
duce a backfire effect, weakening the prosecution’s
case among jurors who do not watch CSI.
Why is there no direct relationship between CSI
and verdict? Intuitively, it seems like such program-
ming should have an effect on jurors’ expectations for
evidence. There is a large body of research identifying
the media as an important source of knowledge and
expectations, particularly for events for which people
have little experience, such as a trial. Should a rela-
tionship between exposure to criminal investigation
programming and juror behavior truly exist, there are
a variety of possible reasons a clear effect has not
emerged in research. As already noted, there are at
least two possible effects viewing CSIcan have on
juror behavior: It can make jurors expect high-quality
forensic evidence and therefore raise the conviction
threshold, or it can lead jurors to believe that all foren-
sic evidence is infallible, thereby lowering the convic-
tion threshold when forensic evidence is present. It is
plausible that both effects may be occurring simulta-
neously, such that jurors are coming to require foren-
sic evidence at trial but at the same time are finding
any forensic evidence sufficient for guilt. These two
effects may therefore be working against each other,
leading to no noticeable change in verdict.
Another possibility is that CSIprogramming may
only influence the behavior of certain types of people.
It has been suggested by Tom Tyler that the overvalu-
ing of forensic evidence caused by exposure to CSI
may be strengthened among those greatly in need of
closure or belief in a just world. Similarly, jurors who
do not have much need for cognition may be more
likely to rely on expectations generated by crime
investigation programming as a cognitive heuristic.
In conclusion, empirical research has yet to iden-
tify a clear CSIeffect, at least as conceptualized by the
legal community and the media. Research efforts
continue in an attempt to ascertain what influence, if
any, such programming has on juror expectations and
behavior.Margaret C. Reardon and Kevin M. O’NeilSee also Jury Competence; Pretrial Publicity, Impact on
Juries; Statistical Information, Impact on Juries176 ———CCSSII EffectC-Cutler (Encyc)-45463.qxd 11/18/2007 12:41 PM Page 176