Don’t Blame the Forensic
Roger G. Koppl
Institute for Forensic Science Administration, FDU
Robert Kurzban
University of Pennsylvania
Lawrence Kobilinsky
John Jay College of Criminal Justice
Research for this talk was supported in part
by the National Science Foundation. Any
opinions, findings, and conclusions or
recommendations expressed in this paper are
those of the authors and do not necessarily
reflect the views of the National Science
Error creates a blame game
Error is a perceived problem
and a real problem
Persons wrongly accused
Labs performing poorly
Proficiency tests
Dror & Charlton studies
MD v Rose
When errors are discovered
• Blame is a common response
• Similar blaming language is used in dissimilar
– Fred Zane “got away with 12 years of sloppy work
and false testimony” (“Reasonable Doubt: Can Crime
Labs Be Trusted?” CNN 1/13/05)
– Jacqueline Blake neglected her negative controls in
DNA tests. “This went on for more than two years
before she was finally caught.” (“Encore
Presentation: Reasonable Doubt” CNN 5/7/06)
• Kelly M. Pyrek: Forensic Science Under Siege,
– Academic Press, 2007
In the blame game we replace one
bad model of the forensic scientist
with another.
The first bad model imagines
forensic scientists to be wonderful
creatures who are never make
mistakes . . .
The second bad model
imagines forensic scientists to
be bumbling incompetents who
should not be allowed anywhere
near criminal evidence. . .
Blame follows glory
Our model . . .
In other words
• Forensic scientists are:
–real, fallible human beings
–Whom we should not blame in an
emotional manner
–But study in a scientific manner
• Leading to a very different take on
The Blame Game is Bad
• “It is time to end this destructive, fatalistic
blame game and replace it with a new
agenda of constructivism.”
– Pyrek, Forensic Science Under Siege, p. 526
• Pyrek rightly cites “To Err is Human:
Building a Safer Health System”
– Institute of Medicine of the National
Academies, 1999
“To Err is Human” p. 49
• The common initial reaction when an error
occurs is to find and blame someone. However,
even apparently single events or errors are due
most often to the convergence of multiple
contributing factors. Blaming an individual
does not change these factors and the same
error is likely to recur. Preventing errors and
improving safety for patients require a systems
approach in order to modify the conditions that
contribute to errors.
James Reason:
“We cannot change the human
condition, but we can change the
conditions under which humans
• Is not a personal problem
– You’re bad
• Requiring a personal solution
– Be good
• It is a structural problem
– Monopoly epistemics
• Requiring a structural solution
– Democratic epistemics
– Structural redundancy
Monopoly vs. Democratic
• A crime lab has a monopoly on the
analysis of evidence sent to it
• That’s “monopoly epistemics”
• Sometimes evidence should be sent to
more than one crime lab
• That’s “democratic epistemics”
Monopoly Epistemics
message set
No match
Crime Lab
The latent was left
by the suspect
Democratic Epistemics
message set
No match
Crime Labs
The latent was left
by the suspect
Monopoly Epistemics
Democratic Epistemics
• Other studies address cost
– Errors are costly: e.g. $100,00
– Forensic tests are cheap: e.g. $50
– Structural redundancy would reduce taxpayer
costs -- if it works to reduce errors
• Our experiments test if it works
Basics of Experimental Design
• Sender(s) evaluate evidence and give a
report to a Receiver
• Receiver guesses the truth given the
• Sender(s) shown one of three shapes:
• Receiver guesses which shape was
Basics of Experimental Design
• Receiver paid $5.00 for correct guesses,
$2.00 for incorrect guesses
• Senders are paid $3.00 for inducing
correct guesses
• Senders are also shown a “supplementary
shape” worth $1.00 or $5.00 depending on
the round.
What the Sender Sees
The supplementary shape is:
The value of the supplementary shape is:
The correct shape is:
On the following page, place a check mark
on the shape you wish to report to DM2. Use
the marker provided.
What the Sender Fills Out
Report Form
One of the DM1 has reported the shape with
the check mark on it.
Monopoly Treatment
• Subjects paired into Senders and Receivers
• Senders informed of “correct shape,”
“supplementary shape,” the value of
supplementary shape
• A $1.00 for the supplementary shape gives
Senders an incentive to issue an accurate report
• A $5.00 value gives Senders an incentive to
issue an inaccurate report -- if the bias does not
agree with truth
Democratic Treatments
• Each Receiver is matched with 2, 3, 4, or
5 Senders
• Otherwise like monopoly treatment
• Major question:
– Do Receiver guesses improve under
democratic epistemics?
Results: Receiver Errors
• Receiver error rates
across all conditions
– 1 Sender: 43%
– 2 Senders: 35%
– 3 Senders: 18%
– 4 Senders: 18%
– 5 Senders: 21%
• Receiver error rates if
Senders have high
– 1 Sender: 51%
– 2 Senders: 55%
– 3 Senders: 33%
– 4 Senders: 36%
– 5 Senders: 43%
So What?
• Structural redundancy works
• Three is the magic number
• Other research shows it will be cost
Closing Remarks
• Forensic Science is a bargain for the
criminal justice system, and we need more
of it.

Forensic Science Administration