1) Is fingerprint examination a science?
Related questions might include:
Are you a scientist?
Is fingerprint examination an art?
What kind of science would you call fingerprint examination?
Into what category of science does FP examination fall?
Is FP examination under the science of ??? (chemistry, biology, genetics, etc.)
Do you have a science degree? Fingerprint degree?
NO DEGREE!!? :)
Concept response: YES it is a science! and Yes, you are a scientist!
Most agree it encompasses a combination of art and science, but mostly applied science, which includes elements of many of the pure sciences; or at
least an understanding of the portions of those sciences which apply to latent
print examination. And we have looked at
degree requirements recently, so
we won't go there again right now.
But you have to be able to articulate why you respond in that way. You
say fingerprint examination is a science because it is! ACE-V follows
the scientific method. Analysis is observing the latent print.
Comparison is experimentation to prove or disprove the
hypothesis/counter-hypothesis (identity/non-identity), and evaluation
corresponds with conclusion. Verification is testing the conclusion. (On
the Detail Archives page, see
also the Detail28 regarding LP
examination corresponding with scientific method)
Latent print examiners can individualize prints because we
have special knowledge of the biological sciences which translate into the
fundamental principles, and we apply that knowledge through scientific method.
We also have to understand our method itself. So latent print examination
encompasses elements of the larger fields of biology, histology, anatomy,
chemistry, genetics, psychology, etc... The term "Ridgeology" was coined
by David Ashbaugh to include putting that knowledge to use in the identification
2) What is the error rate of fingerprint examination?
What about the 1995 CTS proficiency test scores?
Have YOU ever made a mistake?
What is the error rate of examiners in your department?
Concept response: distinguish which type of error you would like to address
first and go for it. I know we said we wouldn't give exact answers, but
this is one case where it wouldn't hurt to say "If by error you mean
practitioner error, then..." "...but if by error you mean the error rate of the
methodology itself, then it is zero."
There are several ways to address practitioner error, including bringing up the
fact that you can't testify regarding the examinations of other practitioners.
You could make an educated guess, if you are in a position to do so. And
you can always bring it home to the fact that a competent examiner correctly
following the ACE-V methodology won't make errors. The bottom line is to
differentiate between the two types of error and drive home the point that the
error rate of the methodology is zero. (more on error rate in the
The fact is, there were many people who had concerns with scores on the 1995 CTS
test, including most examiners! Upon further inquiry, some of the reasons
for the poor performance that year included non-fingerprint examiners being able
to take the test and agencies making photocopies of the test for distribution to
their staff. Here, It should be added that scores have drastically
improved since that year, and Ken Smith, Chair of the Certification Board of the
IAI, has found an approximate error rate of 2% among practitioners of accredited
laboratories on the CTS test in recent years. However, I don't know if it
is a good idea to volunteer this on the stand, simply because it might be
misunderstood, unless fully explained, that the error rate of the methodology was 2%. I believe the
best route to go on this issue is sticking by 0% for the methodology and unknown
/ not applicable error rate for practitioners, unless you actually know.
You should always be prepared to address the issue of mistakes, first by
defining what is meant by mistake. Ron Smith advises defining it yourself;
for example, "If by mistake you mean have I ever misspelled a word in a report
or dropped a jar of fingerprint powder, then sure I have done that... but if you
mean have I ever effected an erroneous identification, then..." and hopefully,
the answer is "no, I have not." But if otherwise, then be prepared to
address the issue however you feel appropriate. (in training, etc...) And
I'm not sure about how to address the issue of examiners in your department.
This would be a good topic for discussion on the
message board. Again, you
could exercise the option not to testify about the examinations of others, but
you and I both know you have a general idea about mistakes in your agency over
the course of several years.
3) Why have fingerprints never been proven to be unique?
You haven't compared all fingerprints...
so how do you
KNOW no two fingerprints are the same?
Scientific "proof" requires an examination of every instance of something.
In order to scientifically prove that all fingerprints are unique, all
fingerprints would have to be compared with all other fingerprints.
Naturally, this is impossible, so it is therefore
impossible to prove the
uniqueness of fingerprints. The theory of
biological uniqueness explains
why no two things have ever been found to be the same. All observations
and data, including statistical modeling and daily AFIS searching, support the
use of fingerprints for personal identification. And no two fingerprints
have ever been found to be the same, which supports biological uniqueness
and disproves the "counter-hypotheses" (that nature WOULD repeat itself.)
In short, the fundamental principles of permanence and uniqueness have been
founded through the study of the biological sciences for over a century.
Medical researchers have confirmed the scientific basis for individualization
through studies in the structure and formation of friction ridges.
*(Cite references) I would say biological uniqueness is one of the
most accepted theories in existence today. (recent
discussion has even established the possibility of referring to it as
the "law" of biological uniqueness) Even the skeptics admit
that nature never repeats itself. Biological uniqueness is the reason no two fingerprints have ever been found to
the be the same, and is also the reason we know they never will.
*References for research / study of permanence and individuality of friction
(This is YOUR Daubert Card, so get to work! Look through Whipple,
Cummins, Hale, Okajima, Babler, etc... For more references to look up,
see the following two articles:
Ashbaugh, D., Ridgeology,
Journal of Forensic Identification, 41(1), 1991
Wertheim, K., Maceo, A., Friction Ridge and Pattern Formation During the
Critical Stage, Journal of Forensic Identification, 52(1), 2002
Isn't Fingerprint Examination Subjective?
Is ACE-V Subjective?
So someone else with MORE experience might arrive at a
How do you explain the results of the FBI study in the
Concept response: Fingerprint examination is mostly objective. (see
the Detail10) The only portion of the
ACE-V process that is subjective is the determination that a sufficient
quality and quantity of information exists to permit individualization, and
that determination is made based on an objective analysis and comparison of
detectable uniqueness, which is naturally affected by the knowledge,
training, skills, and experience of that examiner.
Depending on the question, you may need to clarify the difference between an
opinion of identity and an opinion of sufficiency. Your answer may
include a number of different elements, and as mentioned above, there
may be variations of the evaluation of poor quality fingerprints. But
the fact remains that two competent latent print examiners who
follow the ACE-V methodology will arrive at the same conclusion of identity
or non-identity when looking at the same evidence.
The purpose of the FBI survey (Detail3)
conducted for the Mitchell trial was to demonstrate the overwhelming general
acceptance of the use of fingerprints as a means of personal identification.
All responses confirmed the acceptance that friction ridges are unique and
permanent, and that in the history of the science, there have never been two
fingerprints found to be the same.
And the fact remains after reading all of the other information about the
survey: No agency incorrectly identified either of the prints in the survey.
5) Have friction ridge arrangements been
scientifically tested and found reliable for individualization?
Isn't there a lack of statistical foundation in fingerprint
This concept addresses the detail itself, not its use by a practitioner.
There has been an enormous amount of testing to support the reliability of
the use of friction ridge skin for identification purposes. Some of
the most recent mathematical research by Sharath Pankanti (IBM Research),
Salil Prabhakar and Anil Jain (Michigan State University) and many many
others before them, test the reliability of the use of level 2 friction
ridge detail arrangements for individualization through frequency studies
and AFIS research. The FBI / Lockheed-Martin 50K X 50K study
demonstrated probabilities associated with two prints containing matching
detail on level 2. (see also the
Numerous statistical models have been proposed for over a century, and they
all support the use of fingerprints for personal identification. Only
very recently have plans been implemented and statistical modeling been
attempted utilizing level three detail.
See also the Detail22 for Christophe Champod's
discussion on the use of statistics. Collect references from YOUR study to
support these statements, but be familiar with the origins of those
particular statistical models or references. We may consider adding more specific
references here later.
6) Do you know of any formal studies to
validate fingerprint matching?
Doesn't the NIJ solicitation demonstrate that no validation
has been conducted in fingerprints?
Over a century of medical study of the structure and formation of
friction ridge skin has validated the fundamental principles of permanence
and uniqueness. If a sufficient quality and quantity of that detail
transfers to a surface, individualization of the source can occur.
There has been a tremendous amount of empirical validation of the use of
fingerprints for individualization. Over a century of thousands of
examiners conducting millions, probably even billions of fingerprint
comparisons around the world has not revealed two areas of skin that are
exactly the same. Further, daily AFIS use around the world since the
1980's has not uncovered two such areas of skin.
Many people were concerned with the wording of that particular NIJ
solicitation, which is why the NIJ offered clarification of their position
in a follow-up
letter: "What underlies this solicitation is the desire for more
research to further confirm the already-existing basis that permits
fingerprints to be used as a means to individualize." Scientific
methodologies and philosophies in any field are routinely examined in light
of new advances in technology in order to challenge established beliefs, and
to confirm and further validate the already-existing basis for their use.
7) Isn't it true that
there are no universally accepted standards in fingerprint examination?
How do you explain differing agency minimum point
Why are training programs different?
There are many universally
accepted standards in fingerprint examination. For example, if there
is a difference in two impressions that cannot be accounted for, then the
impressions do not match. That is a standard that every examiner
trained to competency adheres to. Another standard would be ACE-V.
Although it may be described differently by some, every practitioner
examines latent impressions in a manner that conforms to this methodology.
(see also the Detail10)
Other standards include classification terminology, a general lack of
reporting probable individualizations, etc...
Point minimums are most widely viewed as quality control measures rather
than standards. (see also the Detail51)
The standard for identification lies within what has to be present in order
for two impressions to match. This is also universal. For
example, conforming to Ashbaugh's philosophy of identification, in order for
one impression to be individualized to an impression of a known source,
there have to be ridge formations, in sequence, having sufficient uniqueness
in order to individualize (exclude every other possible source). These
four elements must be fulfilled, or else individualization can not occur.
Training programs are designed to train to competency. Although the
details of programs may differ, the end result is (hopefully) a competent
latent print examiner who conducts comparisons accurately each and every
time. The standard is training to competency.
Have all elements of fingerprint examination been peer reviewed?
Related questions might include:
Do you feel it is important for peer review outside the
The fingerprint field and it's theories and techniques have been published
and peer reviewed during a period of over a hundred years. This
includes publication in peer-review journals outside the scope of
9) Would you consider fingerprint examination a
law enforcement function?
Other sub-concepts include:
What other applications are there for fingerprint
Most of the early pioneers of fingerprint identification were scientists and
doctors from around the world. Today, the science of fingerprints has
wide acceptance in business, academic, scientific and biometric communities.
Although friction ridge skin identification is primarily used in
law-enforcement environments, it is also used:
-in hospitals for newborn identification
-in the military for casualty identification
-in the identification of deceased victims of mass
-increasingly in security devices, such as touch-pad
locks in airports,
or home and automobile keyless entry systems.
10) How can you justify
using small distorted fragments for individualization?
Other sub-concepts include:
What if there was a dissimilarity you could not see
outside the matching area of an identification?
No two touches are ever exactly the same, therefore all impressions contain
some level of distortion. No friction ridge skin impression contains
all the detail present on the source, therefore all prints are partial
recordings. In short, all impressions, known and unknown, are "partial, distorted
fragments." The real issue is whether there is a detectable quality
and quantity of uniqueness to permit individualization. Once identity
has been established, the examiner knows that any further recording of the
print would have also matched. Therefore, if an individualization has
been made (by a competent examiner following the correct ACE-V methodology),
it is understood that suggesting a dissimilarity outside that available area
is to propose an impossible situation. If an examiner does not truly
believe that with the print in question, they should reconsider the