Examination of Firearms Review: 2007 to 2010 - Interpol

tested (whether pre-trial beliefs regarding DNA, the reliability of the laboratory, or the
style of cross-examination influenced the verdict (157)).
Starting from dictionary definitions of the words ‘subjective’ and ‘objective’, Leo
develops arguments in relation to different court cases where the use of the word
‘subjective’ was important, according to this analysis (191).
An important change occurs in the argument about fingerprint identification: it is
being more and more considered an opinion, based on the specialists judgement,
rather than fact (158-160).
Bias
Review papers in the subject of cognitive bias are now available (26, 192, 193). A
short summary of the research contributions made during the reviewing period is
given hereinafter.
Whitman and Koppl (161) discusses biasing effects of the justice system and the
integration of forensic services with the police, as well as reaction possibilities. This
article also discusses ‘verification shopping’, which consists in searching for
someone who will verify the original conclusions. Dror and Rosenthal describe two
previously published studies and carry out a meta-analysis, reuniting the effects of
bias observed in those two studies; the effect size thus obtained is quite large and
with a p-value of 0.015 would generally be considered to be significant (162). Bias in
verification has been tested for both experts (n=43) and novices (n=86). Three
groups were created for both the experts and the novices. The first group carried out
comparisons without any information (control), the second group received the
comparisons and had answers provided that were stated to have been given by a
fingerprint examiner trained to competency (low bias group); in the third group, the
answers provided were said to come from prominent and internationally recognized
expert (high bias group). For experts, there was a significant increase in inconclusive
opinions in the low and high bias groups with respect to the control group. This
increase is larger for the three different source trials than for the three same source
trials (only one of the same source trials produced inconclusive opinions). One trial
lead to an increase in the relative frequency of experts’ conclusion towards the bias
prompt; in this trial the ground truth was different source, and the bias prompt was
inconclusive. For novices, there were more inconclusive conclusions for the different
source trials than for the same source trials, but there were not more inconclusive
opinions in the bias groups with respect to the control group. There was, for novices,
an increase in the relative percentage of responses in agreement with the bias
prompt in the bias groups with respect to the control group (163).
Dror analyses the sources of biases that are represented by the four idols of Francis
Bacon, in order to improve forensic science by identifying such vulnerabilities (164).
A study has been carried out with 70 fingerprint examiners, in a way resembling
verification, and declared as an experiment. Examiners were in two groups, high and
low emotional context (an allegation of murder and one of forgery). This study did not
find any bias effects (165). The study has been criticised concerning both
experimental flaws and problems with the interpretation of the data (166, 167). The
authors react to both of these criticisms (168, 169).
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