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Editor: Colin Miller
Univ. of South Carolina School of Law

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Monday, June 13, 2011

Demystifying The Myth Of Fingerprints: The NCSTL's Introductory Video And The San Diego Courthouse Bomber Case

The use of fingerprint evidence is always an interesting issue in Evidence and Expert Evidence classes. So, what is the history of fingerprinting? How about SWGFAST? ACE-V? A friction ridge? A few weeks ago, I posted an entry about the fine folks at the National Clearinghouse for Science, Technology, and the Law (NCSTL) at the Stetson University College of Law and the terrific content that they are producing. Well, they have just put out a terrific two-and-a-half minute video that delves into these and other issues and would serve as a nice introduction to the material in an evidence-related class:

Meanwhile, if you are looking for a solid case that delves into many of these topics, you could do a lot worse than the recent opinion of the United States District Court for the Southern District of California in United States v. Love, 2011 WL 2173644 (S.D. Cal. 2011).

Donny Love, Sr. was convicted of the use of a weapon of mass destruction and other charges arising from the bombing of the Edward J. Schwartz Federal Courthouse in San Diego on May 4, 2008. Prior to his trial, Love moved to exclude the testimony of Robin Ruth, the standards and practices program manager of Federal Bureau of Investigation's latent fingerprint unit, who analyzed fifteen latent prints that connected Love to the crime. In addressing this motion, the United States District Court for the Southern District of California began by noting that

There are, broadly speaking, two kinds of fingerprints. "Rolled," "full," or "known" prints are taken under controlled circumstances, often for official use. "Latent" prints, by contrast, are left—often unintentionally—on the surfaces of objects touched by a person. Latent fingerprint examiners compare unidentified latent prints to known prints as a means of identifying the person who left the latent print.

The court then cited to the Third Circuit's opinion in United States v. Mitchell, 365 F.3d 215 (3rd Cir. 2004), which provides a nice introduction to latent fingerprint terminology and methodology: 

[f]ingerprints are left by the depositing of oil upon contact between a surface and the friction ridges of fingers. The field uses the broader term "friction ridge" to designate skin surfaces with ridges evolutionarily adapted to produce increased friction (as compared to smooth skin) for gripping. Thus toeprint or handprint analysis is much the same as fingerprint analysis. The structure of friction ridges is described in the record before us at three levels of increasing detail, designated as Level 1, Level 2 and Level 3. Level 1 detail is visible with the naked eye; it is the familiar pattern of loops, arches, and whorls. Level 2 detail involves "ridge characteristics"-the patterns of islands, dots, and forks formed by the ridges as they begin and end and join and divide. The points where ridges terminate or bifurcate are often referred to as "Galton points," whose eponym, Sir Francis Galton, first developed a taxonomy for these points. The typical human fingerprint has somewhere between 75 and 175 such ridge characteristics. Level 3 detail focuses on microscopic variations in the ridges themselves, such as the slight meanders of the ridges (the "ridge path") and the locations of sweat pores. This is the level of detail most likely to be obscured by distortions.
The FBI...uses an identification method known as ACE–V, an acronym for "analysis, comparison, evaluation, and verification." The basic steps taken by an examiner under this protocol are first to winnow the field of candidate matching prints by using Level 1 detail to classify the latent print. Next, the examiner will analyze the latent print to identify Level 2 detail (i.e., Galton points and their spatial relationship to one another), along with any Level 3 detail that can be gleaned from the print. The examiner then compares this to the Level 2 and Level 3 detail of a candidate full-rolled print (sometimes taken from a database of fingerprints, sometimes taken from a suspect in custody), and evaluates whether there is sufficient similarity to declare a match....
At the evaluation step, the examiner may reach three conclusions—that the prints are a match ("identification"), that the prints are not a match (“exclusion”), or that more information is needed ("inconclusive")...."In the final step, the match is independently verified by another examiner."

The Southern District of California then went on to note, "that since Mitchell was decided in 2004, there have been important refinements and developments with respect to latent print identification...."

This introduction led the court into the law, specifically Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), which held that in determining whether expert testimony is based upon reliable principles and methods under Federal Rule of Evidence 702, courts can consider factors such as

whether the "technique can be (and has been) tested," "[w]hether it has been subjected to peer review and publication," the "known or potential rate of error," "whether there are standards controlling the technique's operation," and "whether the...technique enjoys general acceptance within a relevant scientific community."

In addition, the court decided to consider two other factors: (1) whether latent fingerprint analysis has a "relationship to...established modes of scientific analysis," and (2) whether it has "non-judicial uses." Briefly, here is what the court held in connection with each factor:

Testing: "The parties do not dispute that the reliability of latent fingerprint analysis can be tested, and the record reveals three categories of potential tests....The fact that latent fingerprint analysis can be tested for reliability, without more, allows the first Daubert 'factor to weigh in support of admissibility.'...Ruth also testified, however, that at least some actual testing and research has been performed....Finally, several studies of the performance of fingerprint examiners have been performed. The most recent such study was published in May 2011....The court recognizes that the NAS Report called for additional testing to determine the reliability of latent fingerprint analysis generally and of the ACE–V methodology in particular....The Report also questions the validity of the ACE–V method....However, Daubert, Kumho, and Rule 702 do not require "absolute certainty"...; instead, they ask whether a methodology is testable and has been tested. On this record, the court finds that latent fingerprint analysis can be tested and has been subject to at least a modest amount of testing—some of which, like the study published in May 2011, was apparently undertaken in direct response to the NAS's concerns. The court therefore concludes that this factor weighs in favor of admitting latent fingerprint evidence." 

Peer Review and Publication: "Publications regarding latent fingerprint analysis are relatively few in number. The government introduced into evidence a list of roughly thirty publications touching on various aspects of the field....Love's moving papers also contain citations to a handful of other relevant publications....Although limited in quantity, many of these publications appear to "address... theoretical/foundational questions" in latent fingerprint analysis....The articles are therefore relevant to the reliability inquiry.

Ruth stated that at least one of these articles was published in a peer-reviewed journal, and the government's brief cites three other examples of peer-reviewed work....Even assuming that all of the articles cited by Ruth and the parties are peer-reviewed, latent fingerprint analysis would have only a small fraction of the number of peer reviewed publications found in established sciences. Nonetheless, because there are a handful of publications that concern the reliability of latent fingerprint analysis, at least a few of which are peer-reviewed, this factor is either neutral or weighs slightly in favor of admissibility."

•Error Rates: "Latent fingerprint examiners have sometimes stated that their analyses have a zero error rate....Ruth did not so testify. Rather, she stated that the ACE–V methodology is unbiased and that the methodology itself introduces no random error. Errors occur, but those errors are human errors resulting from human implementation of the ACE–V process....Because human errors are nonsystematic, Ruth believes that there is no overall predictive error rate in latent fingerprint analysis.

Ruth's testimony does not mean that the ACE–V process is perfect, or even that it is necessarily the best possible process for identifying latent prints....Nevertheless, all of the relevant evidence in the record before the court suggests that the ACE–V methodology results in very few false positives—which is to say, very few cases in which an examiner identifies a latent print as matching a known print even though the two prints were actually made by different individuals. Most significantly, the May 2011 study of the performance of 169 fingerprint examiners revealed a total of six false positives among 4,083 comparisons of non-matching fingerprints for "an overall false positive rate of 0.1%."

The court therefore concludes that the error rate favors admission of latent fingerprint evidence."

Standards: Here, the court noted that "[i]t is not disputed that the ACE–V methodology leaves much room for subjective judgment" and that "[t]here is not a single national standard" to guide an examiner's judgment. The court, however, focused upon standards imposed by the FBI's latent fingerprints unit to find that this factor favored admission:

"The FBI uses three different types of standards in an effort to reach reliable conclusions through the ACE–V process. At the laboratory level, the FBI adheres to the standards for calibration laboratories provided by the International Organization for Standardization and the standards for forensic laboratories promulgated by the American Society of Crime Laboratory Directors Laboratory Accreditation Board ("ASCLD/LAB")....The FBI also follows the consensus-based guidelines for laboratories engaged in friction ridge analysis issued by the Scientific Working Group on Friction Ridge Analysis Study and Technology.

At the level of individual examiners, the FBI applies relatively stringent standards for qualification. In addition to a college degree, examiners must have a significant amount of training in the physical sciences. They are then given eighteen months of FBI training and a four-day proficiency examination. After passing that test, an examiner has a six-month probationary period in which every aspect of her work is fully reviewed. Even thereafter, examiners undergo annual audits, proficiency tests, and continuing education.

Finally, at the level of individual comparisons and evaluations, the ACE–V methodology provides procedural standards that must be followed, such as the requirement that examiners assess each ridge and ridge feature in the prints under comparison....The FBI has also recently incorporated documentation requirements that record the process used to detect latent prints as well as the examiner's comparison of the latent print to a known print. These documentation requirements and other procedures are enforced through the technical and administrative review of examiners' work. And the verification process serves as an error-reducing backstop."

General Acceptance: "The NAS report does demonstrate some hesitancy in accepting latent fingerprint analysis on the part of the broader scientific community. Love's claim is subject to two significant qualifications. First, the NAS report itself states that "friction ridge analysis has served as a valuable tool, both to identify the guilty and to exclude the innocent."...Instead of a full-fledged attack on friction ridge analysis, the report is essentially a call for better documentation, more standards, and more research.

Second, Love does not dispute that the forensic science and law enforcement communities strongly support the use of friction ridge analysis. Acceptance in that narrower community is also relevant to the Daubert inquiry....For both of these reasons, the court concludes that the general acceptance factor at least weakly supports the admission of latent fingerprint evidence."

Relationship to Established Techniques: "The Third Circuit held in Mitchell, and Ruth testified, that friction ridge analysis is related to the undisputeclly scientific "fields of developmental embryology and anatomy,” which explain “the uniqueness and permanence of areas of friction ridge skin."...Love argues that this strong tie to the biological sciences is irrelevant, because "'uniqueness and persistence are necessary'" but not sufficient conditions for friction ridge analysis to be reliable....Even if uniqueness and persistence alone cannot validate latent fingerprint analysis, however, it remains true that "[i]ndependent work in [developmental embryology and anatomy] bolsters" two critical "underlying premises of fingerprint identification."...This factor weighs in favor of admission."

Non-Judicial Applications: "Ruth testified that friction ridge analysis is used for various other purposes, including to identify disaster victims, to identify newborns at hospitals, for biometric devices, for some passports and visas, and for certain jobs....Love stresses that these non-judicial applications generally use rolled and not latent prints. Ruth testified, however, that latent prints are used to identify disaster victims when rolled prints are unavailable....On the basis of the widespread use of fingerprints, and occasional use of latent prints, for non-judicial identification purposes, the court concludes that this factor modestly supports the admission of latent fingerprint evidence."

Based upon all of these factors, the court easily concluded that the latent fingerprint testimony was admissible.

-CM

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