Friday, December 16, 2011

Abusing AFIS -- Conviction by Computer?

On television shows such as NCIS, seconds after a forensic scientist inserts an image of a latent fingerprint into a machine connected to an automated fingerprint identification system (an AFIS), a computer screen blinks MATCH FOUND ... MATCH FOUND ... MATCH FOUND ... , and the chase is on. Apparently, some police and prosecutors think this is real.

Robert Garrett, a past president of the International Association for Identification, writing in the Evidence Technology Magazine, describes three cases in which governments have taken very serious actions against individuals based solely on the output of an AFIS search — with no review by any latent print examiner [1]. AFIS searches generate a list of potential matches — often the 20 closest matches as determined by an algorithm that looks at prints very differently from the way humans do. There is no proof that the AFIS ranks the candidates in the way that a skilled human examiner, relying on more information in the images, would. A number 1 candidate can be an obvious mismatch (to the human eye and brain). The Scientific Working Group on Friction Ridge Analysis, Study, and Technology (SWGFAST) insists that “AFIS ranks and scores have no role in formulating and stating conclusions based on ACE-V,” the steps that latent print examiners follow [2] and that “[t]he practice of relying on current AFIS technology to individualize latent prints correctly is not sound” [3].

According to Mr. Garrett, U.S. Customs and Immigration Enforcement relies on raw AFIS results to initiate deportation proceedings, and grand juries issue indictments relying on this information without testimony from a qualified examiner that the AFIS match means anything [1, p.10]. He concludes that “AFIS hits must be examined by a qualified fingerprint examiner and the results of that examination verified before any proceedings are commenced against a potential suspect. It is unethical, unprofessional, and—most likely—unconstitutional to do otherwise” [1, p. 11].

I would not presume to question Mr. Garrett’s professional judgment of what is unprofessional conduct in the fingerprint expert community, but it seems fair to ask on what basis he concludes that the practice of using unreviewed AFIS output is “most likely ... unconstitutional.” The article offers two possible bases for this judgment. First, Mr. Gerrett writes that
U.S. Supreme Court decisions in Melendez-Diaz v. Massachusetts and, more recently, Bullcoming v. New Mexico, reiterated a defendant’s Sixth Amendment right “to be confronted with the witnesses against him.” Reports of a laboratory or investigative finding do not satisfy the requirement.
This won’t wash. The Sixth Amendment right to confrontation is a trial right. It does not apply to administrative and grand jury proceedings. Even the usual rules for expert evidence are not binding in these proceedings. At trial, an AFIS hit, not used as part of the basis for an examiner’s opinion, would be impermissible under the rules of evidence, since this kind of scientific evidence is neither scientifically valid (under Daubert) nor generally accepted in the scientific community (per Frye). But this does not make it unconstitutional. An argument could be made that it deprives the defendant of due process to be convicted on the strength of such evidence. Cf. McDaniel v. Brown, 130 S.Ct. 665 (2010). However, the Confrontation Clause line of cases on which Mr. Garrett relies suggests that “machine-generated” test results can be introduced without the separate judgment of a human examiner. The state of Illinois currently is seeking to exploit this idea — unpersuasively in the judgment of many commentators — in the pending Supreme Court case of Williams v. Illinois (involving DNA tests and discussed on other postings on this blog).

The second suggestion regarding the constitutionality of AFIS evidence is that
Our society and its government have embraced technology in various forms for its efficiency and economy. In the areas of law enforcement and public safety, these technological advances have included AFIS, the Combined DNA Index System (CODIS), airport security screening devices, and red light/traffic cameras. But these advances bring with them compromises of privacy and our right “…to be secure in their persons, houses, papers, and effects…”
It would be extravagant to assert that AFIS, CODIS, airport magnetometers and ordinary scanners, and red light cameras are “most likely unconstitutional,” and this may not be what Mr. Garrett intended to state or imply.

In any event, the article is an eye-opener. Police and prosecutors who rely on unexamined AFIS matches are not acting professionally or responsibly. Mr. Garrett deserves thanks for shedding some light on this remarkable practice.


1. Robert J. Garrett, Automated Fingerprint Identification Systems (AFIS) and the Identification Process, Forensic Sci. Mag., July-Aug. 2011, at 10–11.

2. SWGFAST, Position Statement on the Role of AFIS Ranks and Scores and the ACE-V Process, Oct. 15, 2011.

3. SWGFAST, Press Kit, May 19, 2004, at 14.1.3.

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