1. Litigating Fingerprint Evidence: Ensuring a Statistical Foundation
Swofford, H.J.
Chair, Friction Ridge Subcommittee, OSAC
Chief, Latent Print Branch, U.S. Army Criminal Investigation Laboratory
Fordham University School of Law, June 2018

3. Calls for Reform
National Research Council Strengthening Forensic Science in the United States: A Path Forward. Washington, DC: The National Academies Press.
Expert Working Group on Human Factors in Latent Print Analysis (U.S.), National Institute of Justice (U.S.), & National Institute of Standards and Technology (U.S.). (2012). Latent print examination and human factors: Improving the practice through a systems approach : the report of the Expert Working Group on Human Factors in Latent Print Analysis. Washington, D.C.: National Institute of Standards and Technology.
REPORT TO THE PRESIDENT, Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods, Executive Office of the President, President’s Council of Advisors on Science and Technology. 2016
American Academy for the Advancement of Science (AAAS), Forensic Science Assessments: A Quality and Gap Analysis, Latent Fingerprint Examination, AAAS, 2017.

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The Issue
Detect
Measure
Evaluate ?
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The Objective
Detect
Measure
Evaluate
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6. Current State of the Practice
Step 1: Analyze the impression to visually assess the quality and quantity of information
Fingerprint image(s) from NIST SD 27; Image license free for public share and use from Clipart

7. Current State of the Practice
Step 2: Compare and visually assess the similarity between the impressions and form an opinion regarding the significance of those measurements
Fingerprint image(s) from NIST SD 27; Image license free for public share and use from Clipart

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Current State of the Practice
Problems:
No measurements taken
No documentation
No standards for interpretation
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Bridging the Gap & Promoting Reform
How? A B
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Future State of the Science
Basic tenets of science:
DOCUMENT the details utilized
MEASURE the attributes of those details
EVALUATE the significance of those measurements
REPORT conclusions which are substantiated by the data
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11. Future State of the Science
Step 1: Measure the quality of the impression & Evaluate the significance of those measurements
Fingerprint image(s) from NIST SD 27; Image license free for public share and use from Clipart

12. Future State of the Science
Step 2: Compare & measure the similarity between the impressions and evaluate the significance of those measurements using empirical datasets
Image license free for public share and use from clipart; Fingerprint Image(s) from NIST SD 27
FRStat Logo depicted above is the property of the U.S. Government

13. Future State of the Science
Measure the similarity between the impressions and evaluate the significance of those measurements using empirical datasets

14. Future State of the Science
RESULTS OF EXAMINATION
The latent print on Exhibit 1 and the standards bearing the name XXXX have corresponding ridge detail. The probability of observing this amount of correspondence is approximately 96,000 times greater when impressions are made by the same source rather than by different sources.
TECHNICAL NOTE
The statistical calculations in this report were generated using FRStat software. Results equal to or greater than 10 indicate a positive association between two impressions. Correspondence is measured with respect to the spatial relationships and angles of the annotated ridge details and reflected as a similarity statistic. Uncertainty of measurement is calculated using an iterative random sampling scheme for the annotated details. The reported result is the lower bound of the 99% confidence interval. FRStat is not designed to evaluate all aspects of the impressions, such as pattern type, feature type, intervening ridge counts, and other details considered by an examiner; thus, the reported results indicate a conservative estimate for the statistical strength of an association between
two impressions.

15. Future State of the Science
“Association” threshold tied to empirically tested data

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Bridging the Gap & Promoting Reform
That sounds great, but not all laboratories have those capabilities Can they implement these capabilities?
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Bridging the Gap & Promoting Reform
YES!!!
Laboratories ARE ABLE to access latent print quality software*
Laboratories ARE ABLE to access statistical interpretation software*
Laboratories ARE ABLE to ensure reported conclusions are grounded by available facts or data
* Available to most US government entities
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18. Bridging the Gap & Promoting Reform

19. Bridging the Gap & Promoting Reform
YOU can help strengthen the foundation of fingerprint examination – hold the expert and laboratory accountable to demonstrate:
WHAT was observed
HOW it was measured
WHY it is “significant”
WHERE is the data to substantiate the conclusion

20. Henry Swofford Chair, Friction Ridge Subcommittee, OSAC
Chief, Latent Print Branch, USACIL
(404)