D  A  U  B  E  R  T     C  A  R  D 
Updated by Steve Scarborough, Ray York, and Kasey Wertheim

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 process. 



2) What is the error rate of fingerprint examination?

Related questions:
    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 Detail1.)

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?

Related questions:

    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 ridge skin:
(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

 

4) Isn't Fingerprint Examination Subjective?

Related questions:
    Is ACE-V Subjective?
    So someone else with MORE experience might arrive at a different conclusion?
    How do you explain the results of the FBI study in the Mitchell trial?


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 correctly 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?

Related questions:
    Isn't there a lack of statistical foundation in fingerprint examination?

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 Detail2) 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?

Related questions:
    Doesn't the NIJ solicitation demonstrate that no validation testing
    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?

Related questions:
     How do you explain differing agency minimum point requirements?
     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.

 

8) Have all elements of fingerprint examination been peer reviewed?

Related questions might include:
    Do you feel it is important for peer review outside the fingerprint community?

Concept response: 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 fingerprints. 

 

9) Would you consider fingerprint examination a law enforcement function?

Other sub-concepts include:
    What other applications are there for fingerprint identification?
    

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 disaster
     -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 identification.