Tibbs. Shipp, and Harris on "Meaningul" Peer Review of Studies on Firearms-toolmark Matching

The Supreme Court's celebrated (but ambiguous) opinion in Daubert v. Merell Dow Pharmaceuticals, \1/ was a direct response to a seemingly simple rule--results that are not published in the peer-reviewed scientific literature are inadmissible to prove that a scientific theory or method is generally accepted in the scientific community. The Court unanimously rejected this strict rule--and more broadly, the very requirement of general acceptance--in favor of a multifaceted examination guided by four or five criteria that have come to be known as "the Daubert factors."

But "peer review and publication" lives on--not as a formal requirement, but as one of these factors. Thus, courts routinely ask whether the peer-reviewed scientific literature supports the reasoning or data that an expert is prepared to present at trial. All too often, however, the examination of the literature is cursory or superficial. The temptation, especially for overburdened judges not skilled in sorting through biomedical and other journals, is to check that there are articles on point, and if  the theory has been discussed (critically or otherwise) in the literature, to write that the "peer review and publication" factor supports admission of the testimony.

One area in which this dynamic is apparent is traditional testimony of firearms examiners matching marks from guns to bullets or shell casings. \2/ Defendants have strenuously objected that traditional associations of particular guns to ammunition components is an inscrutable judgment call that does not pass muster under Daubert. Perhaps the most meticulous analysis of this issue comes from an unpublished opinion of Judge Todd Edelman in United States v. Tibbs. \3/ Judge Edelman's discussion of peer review and publication is unusually thorough and may have been penned as an antidote to the strategy in which the government gives the court a laundry list of articles that have discussed the procedure and the court checks off the "peer review and publication" box.

Being an opinion for a trial court (the District of Columbia Superior Court), Tibbs is not binding precedent for that court or any other, but it has not gone unnoticed. Two federal district courts recently reached mutually opposing conclusions about Judge Edelman's analysis of one large segment of the literature cited in support of admitting match determinations--namely, the extensive research reported in the AFTE Journal. ("AFTE" stands for the Association of Firearms and Toolmark Examiners. The organization was formed in 1969 in "recognition of the need for the interchange of information, methods, development of standards, and the furtherance of research, [by] a group of skilled and ethical firearm and/or toolmark examiners" who "stand prepared to give voice to this otherwise mute evidence." \4/)

Tibbs' Analysis of the AFTE Journal

Because of the AFTE Journal's orientation and editorial process, Tibbs did not give "the sheer number of studies conducted and published" there much weight. \5/ Judge Edelman made essentially four points about the journal:

• Contrary to the testimony of the government’s experts, post-publication comments or later articles are not normally considered to be “peer review”;
• The AFTE pre-publication peer review process is “open,” meaning that “both the author and reviewer know the other's identity and may contact each other during the review process”;
• The reviewers who form the editorial board are all “members of AFTE” who may well “be trained and experienced in the field of firearms and toolmark examination, but do not necessarily have any ... training in research design and methodology” and who “have a vested, career-based interest in publishing studies that validate their own field and methodologies”; and
• “AFTE does not make this publication generally available to the public or to ... reviewers and commentators outside of the organization's membership [and] unlike other scientific journals, the AFTE Journal ... cannot even be obtained in university libraries.” \6/

The court contrasted these aspects of the journal’s peer review to a "double-blind" process and observed that the AFTE “open” process was “highly unusual for the publication of empirical scientific research.” \7/ The full opinion, which develops these ideas more completely can be found online.

Shipp

Senior Judge Nicholas Garaufis of the Eastern District of New York was impressed with "this thorough opinion." \8/ His opinion in United States v. Shipp referred to the "several pages analyzing the AFTE Journal's peer review process [that] highlight[] several reasons for assigning less weight to articles published in the AFTE Journal than in other publications" and added that

The court shares these concerns about the AFTE Journal's peer review process. In particular, the court is concerned that the reviewers, who are all members of the AFTE, have a vested, career-based interest in publishing studies that validate their own field and methodologies. Also concerning is the possibility that the reviewers may be trained and experienced in the field of firearms and toolmark identification, but [may] not necessarily have any specialized or even relevant training in research design and methodology. \9/

Harris

In contrast, Judge Rudolph Contreras of the U.S. District Court for the District of Columbia, writing in United States v. Harris, \10/ had nothing complimentary to say about Tibbs. This court defended the AFTE Journal research articles said to demonstrate the validity of firearms-toolmark identification with two rejoinders to Tibbs. First, Judge Contreras maintained that “there is far from consensus in the scientific community that double-blind peer review is the only meaningful kind of peer review.” \11/ This is true enough, but the issue raised by the criticism of “open” review is not whether double-blind review is better than single-blind review (in which the author does not know the identity of the referees) or some other system. It is whether “open” review conducted exclusively by AFTE members is the kind of peer review envisioned as a strong indicator of scientific soundness in Daubert. The factors enumerated in Tibbs make that a serious question.

Second, Judge Contreras observed that the Journal of Forensic Sciences, which uses double-blind review, republished one AFTE study. This solitary event, the Harris opinion suggests, is a “compelling” rebuttal of “the allegation by Judge Edelman in Tibbs that the AFTE Journal does not provide 'meaningful' review." \12/ But Judge Edelman never proposed that every article in the AFTE journal was without scientific merit. Rather, his point was far less extreme. It was merely that courts should not “accept at face value the assertions regarding the adequacy of the journal's peer review process.” \13/ That one article—or even dozens—published in the AFTE Journal could have been published in other journals reveals very little about the level and quality of AFTE review. After all, even a completely fraudulent review process that accepted articles for publication by flipping a coin would result in the publication of some excellent articles—but not because the review process was meaningful or trustworthy. In addition, one might ask whether the very fact that an article had to be republished in a more widely read journal fortifies the fourth point in Tibbs, that the journal’s circulation is too restricted to make its publications part of the mainstream scientific literature. The discussion of peer review and publication in Harris ignores this concern.

Beyond the AFTE Journal

The significant concerns exposed in Tibbs do not prove that the peer-reviewed scientific literature, taken as a whole, undermines firearms identification as commonly practiced. They simply mean that the list of publications over the years in the AFTE Journal may not be entitled to great weight in evaluating whether the scientific literature supports the claim of firearms and toolmark examiners to be able to supply generally accurate and reliable "opinions relative to evidence which otherwise stands mute before the bar of justice." \14/

Fortunately, newer peer-reviewed studies exist, and not all the older research appears in the AFTE Journal. \15/ Thus, the Harris court asserted that

[E]ven if the Court were to discount the numerous peer-reviewed studies published in the AFTE Journal, Mr. Weller's affidavit also cites to forty-seven other scientific studies in the field of firearm and toolmark identification that have been published in eleven other peer-reviewed scientific journals. This alone would fulfill the required publication and peer review requirement. \16/

The last sentence could be misunderstood. As a statement that the 47 studies could be the basis of an scientifically informed judgment about the validity of firearms-toolmark matching, the conclusion is correct. As a statement that checking the "peer review and publication" box on the basis of a large number of studies published in the right places "alone" is a reason to admit the challenged testimony, it would be more problematic. The "required ... requirement" (to the extent Daubert imposes one) is for a substantial body of peer-reviewed papers that form a solid foundation for a scientific assessment of a method. Unless this research literature is actually supportive of the method, however, satisfying the "the required publication and peer review requirement" is not a reason to admit the evidence. 

Do the 47 studies (old and new) in widely accessible, quality journals all show that examiners' opinions derived from comparing toolmarks are consistently correct and stable for the kinds of comparisons made in practice? If so, then it is high time to stop the arguments over scientific validity. If not, if the 47 studies are of varying quality, scope, and relevance to ascertaining how repeatable, reproducible, and accurate the opinions rendered by firearms-toolmark examiners are, then there is room for further analysis of whether and how these experts can provide valuable information for the legal factfinders.

NOTES

1. 509 U.S. 579 (1993),
2. No. 2016 CF1 19431, 2019 D.C. Super. LEXIS 9, 2019 WL 4359486 (D.C. Super. Ct., Sept. 5, 2019).
3. "[T]he process that most firearms examiners use when analyzing evidence" is desctibed in graphic detail in "[t]he Firearms Process Map, which captures the ‘as-is’ state of firearms examination, provides details about the procedures, methods and decision points most frequently encountered in firearms examination." NIST, OSAC's Firearms & Toolmarks Subcommittee Develops Firearms Process Map Jan. 19, 2021, https://www.nist.gov/news-events/news/2021/01/osacs-firearms-toolmarks-subcommittee-develops-firearms-process-map.
4. AFTE Bylaws, Preamble, https://afte.org/about-us/bylaws
5. 2019 D.C. Super. LEXIS 9, at *35. For a decade or so, both legal academics and forensic scientists had pointed to the AFTE Journal as an example of a practitioner-oriented outlet for publications that did not follow the peer review and publication practices of other scientific journals. See, e.g., David H. Kaye, Firearm-Mark Evidence: Looking Back and Looking Ahead, 68 Case W. Res. L. Rev. 723 (2018); Jennifer L. Mnook--n et al., The Need for a Research Culture in the Forensic Sciences, 58 UCLA L. Rev. 725 (2011).
6. 2019 D.C. Super. LEXIS 9, at *32-*33.
7. Id. at *33.
8. United States v. Shipp, 422 F.Supp.3d 762, 776 (E.D.N.Y. 2019).
9. Id. (citations and internal quotation marks omitted). Nevertheless, the court found "sufficient peer review." It wrote that "even assigning limited weight to the substantial fraction of the literature that is published in the AFTE Journal, this factor still weighs in favor of admissibility. Daubert found the existence of peer-reviewed literature important because “submission to the scrutiny of the scientific community ... increases the likelihood that substantive flaws in the methodology will be detected.” Daubert, 509 U.S. at 593. Despite AFTE Journal’s open peer-review process, the AFTE Theory has still been subjected to significant scrutiny. ... Therefore, the court finds that the AFTE Theory has been sufficiently subjected to 'peer review and publication' [outside of the AFTE Journal].” Daubert, 509 U.S. at 594."
10. 502 F.Supp.3d 28 (D.D.C. 2020).
11. Id. at 40.
12. Id.
13. Tibbs, 2019 D.C. Super. LEXIS 9, at *29.
14. AFTE Bylaws, Preamble, https://afte.org/about-us/bylaws.
15. AFTE has sought to remedy at least one complained-of feature of its peer review process. In 2020, it instituted the double-blind peer review that the Harris court found unnecessary. AFTE Peer Review Process – January 2020, https://afte.org/afte-journal/afte-journal-peer-review-process. Whether the qualifications and backgrounds of the journal's referrees have been changed is not apparent from the AFTE website.
16. Harris, 502 F.Supp.3d at 40.