More on Pitts and Lundi: Why Bother with Opposing Experts?

In the post-PCAST cases of United States v. Pitts 1/ and United States v. Lundi 2/, the government prevented a scholar of the development and culture of fingerprinting from testifying for the defense. The proposed witness was Simon Cole, Professor of Criminology, Law and Society at the Department of Social Ecology of the University of California (Irvine). Pitts “contend[ed] that Dr. Cole’s testimony [was] necessary ‘contrary evidence’ that calls into question the reliability of fingerprint analysis.” Lundi wanted Cole to testify about “forensic print analysis, in particular in the areas of accuracy and validation,” including "best practices." The federal district court would not allow it.

Qualifications of an Expert Witness

In Pitts, the government first denied that Cole had the qualifications to say anything useful about fingerprinting. It maintained (in the court's words) that “Dr. Cole (1) is ‘not a trained fingerprint examiner’; (2) ‘has not published peer-reviewed scientific articles on the topic of latent fingerprint evidence’; and (3) ‘has not conducted any validation research in the field.’” The court neither accepted nor clearly rejected this argument, for it decided to keep Cole away from the jury on a different ground.

Exclusion for lack of qualifications would have done violence to Federal Rule of Evidence 702. First, Cole was not going to offer an opinion as a criminalist (which he is not) nor as an interdisciplinary scholar (which he is) on whether the examiner in the case had accurately perceived, compared, and evaluated the images. More likely, he would have opined on the extent to which scientific studies have shown that fingerprint examiners can distinguish between same-source and different-source prints. Training and experience in conducting fingerprint identifications is largely irrelevant to this task.

Second, Rule 702 does not require someone to publish peer-reviewed articles on a topic to be qualified to give an opinion as to the state of the scientific literature. Epidemiologists and toxicologists, for example, can opine about the toxicity of a compound without first publishing their own research on the compound's toxicity. Finally, there is no support in logic or law for the notion that someone has to conduct his or her own validity study to have helpful information on the studies that others have done and what these studies prove.

The Panacea of Cross-examination

The government’s other argument was “that Dr. Cole’s testimony will not assist the trier of fact.” But this argument was garbled:

Specifically, the government points out that Dr. Cole’s only disclosed opinion is that the government’s expert’s testimony “exaggerates the probative value of the evidence because such testimony improperly purports to eliminate the probability that someone else might be the source of the latent print.” “Professor Cole fails to provide any analysis of why latent fingerprint evidence [in general] is so unreliable that it should not be submitted to the jury or, if such evidence can be reliable in some circumstances, what precisely the NYPD examiners did incorrectly in this case.” Dr. Cole is not expected to testify that the identification made by the government’s expert in this case is unreliable or that the examiners made a misidentification. Therefore, the government argues Dr. Cole’s opinion goes to the weight of the government’s evidence, not its admissibility. (Citations and internal quotation marks omitted.)

Chief Judge Dora L. Irizarry had already ruled that a source attribution made with an acknowledgment of at least a theoretical possibility that the match could be a false positive was admissible. If expert evidence is admitted, the opposing party is normally permitted to counter it with expert testimony that it deserves little weight. To argue that just because evidence goes to weight, rebuttal evidence about its weight is inadmissible makes no sense.  Once the evidence is admitted, it's weight is the only game in town.

The real issue is what validity or possibility-of-error testimony would add to the jury's knowledge. In this regard, Judge Irizarry wrote that

The Court is not convinced that Dr. Cole’s testimony would be helpful to the trier of fact. The only opinion Defendant seeks to introduce is that fingerprint examiners “exaggerate” their results to the exclusion of others. However, the government has indicated that its experts will not testify to absolutely certain identification nor that the identification was to the exclusion of all others. Thus, Defendant seeks admit Dr. Cole’s testimony for the sole purpose of rebutting testimony the government does not seek to elicit. Accordingly, Dr. Cole’s testimony will not assist the trier of fact to understand the evidence or determine a fact in issue. (Citations omitted.)

At first blush, this seems reasonable. If the only thing Cole was prepared to say was that fingerprinting does not permit “absolutely certain identification,” and if the fingerprint examiners will have said this anyway, why have him repeat it?

But surely Cole (or another witness— say, a statistician) could have testified to something more than that. An expert with statistical knowledge could inform the jury that although there is very little direct evidence on how frequently fingerprinting experts err in making source attributions in real casework, experiments have tested their accuracy, and the researchers detected errors at various rates. This information could “assist the trier of fact to understand the evidence or determine a fact in issue.” So why keep Cole from giving this “science framework” testimony?

The court’s answer boils down to this:

Moreover, the substance of Dr. Cole’s opinion largely appears in the reports and attachments cited in Defendant’s motion to suppress .... For example, Dr. Cole’s article More Than Zero contains a lengthy discussion about error rates in fingerprint analysis and the rhetoric in conveying those error rates ... , and the PCAST Report notes that jurors assume that error rates are much lower than studies reveal them to be (PCAST Report at 9-10 (noting that error rates can be as high as one in eighteen)). Defendant identifies no additional information or expertise that Dr. Cole’s testimony provides beyond what is in these articles and does not explain why cross-examination of the government’s experts using these reports would be insufficient. 3/

Now, I think the 1 in 18 figure is mildly ridiculous, 4/ but there is no general rule that because published findings could be introduced via cross-examination, a party cannot call on an opposing expert to present or summarize the findings. First, the expert being cross-examined might not concede that the findings are from authoritative sources. This occurred repeatedly when a number of prosecution DNA experts flatly refused to acknowledge the 1992 NAS report on forensic DNA technology as authoritative. That created a hearsay problem for defendants. After all, the authors of the report were not testifying and hence were not subject to cross-examination. The rule against hearsay applies to such statements because the jury would have to evaluate the truthfulness of the statements without hearing from the individuals who wrote them.

Therefore, counsel could not quote or paraphrase the report’s statements over a hearsay objection unless the report fell under some exception to the rule against hearsay. The obvious exception—for “learned treatises”—does not apply unless the report first is “established as a reliable authority by the testimony or admission of the witness or by other expert testimony or by judicial notice.” 5/

In Pitts, however, it appears that the government’s experts were willing to concede that the NAS and PCAST reports were authoritative (even though a common complaint from vocal parts of the forensic-science community about both reports was that they were not credible because they lacked representation from enough practicing forensic scientists). Moreover, a court might well have to admit the PCAST report under the hearsay exception for government reports.

Nonetheless, a second problem with treating cross-examination as the equivalent of testimony from an opposing expert is that it is not equivalent. By way of comparison, would  judges in a products liability case against the manufacturer of an alleged teratogen reason that the defense cannot call an expert to present and summarize the results of studies that address the strength of the  association between exposure and birth defects but rather can only ask the plaintiff’s experts about the studies?

In criminal cases, even if the defense expert eschews opinions on whether the defendant is the source of the latent prints as beyond his (or anyone’s?) expertise, the jury might consider this expert to be more credible and more knowledgeable about the underlying scientific literature than the latent print examiners. Examiners understandably can have great confidence in their careful judgments and in the foundations of the important work that they do. It would not be surprising for their message on cross-examination (or re-direct examination) to be, yes, errors are possible and they have occurred in artificial experiments and a few extreme cases, but, really,the process is highly valid and reliable. An outside observer may have a less sanguine perspective to offer even when discussing the same underlying literature.

Cross-examination is all well and good, but cross-examination of experts is delicate, difficult, and dangerous. Confining the defense to posing questions about specific studies in lieu of its own expert testimony about these studies is not normal. Court instructions about error probabilities (analogous to instructions about the factors that degrade eyewitness identifications) might be a device to avoid unduly time-consuming defense witnesses, but those do not yet exist. The opportunity to cross-examine the other party's witnesses rarely warrants depriving a party of the right to present testimony from its experts.

NOTES

1. United States v. Pitts, 16-CR-550 (DLI), 2018 WL 1169139 (E.D.N.Y. Mar. 2, 2018).
2. United States v. Lundi, 17-CR-388 (DLI), 2018 WL 3369665 (E.D.N.Y. July 10, 2018).
3. The opinion in Lundi is similar:

   The government seeks to preclude Defendant’s proposed expert, Dr. Cole, from testifying, and points to this Court’s decision in Pitts, ... . The government argues that, as was the case in Pitts, Dr. Cole’s anticipated testimony would serve to rebut testimony from the government’s experts that the government does not expect to elicit. ... The government argues further that Dr. Cole’s additional proposed testimony, which would address the reliability of fingerprint examinations and the “best practices” to be followed when conducting such examinations, is not distinguishable from the information contained in the reports Defendant attached to his motion, and with which he can cross examine the government’s experts. ...
   
   Defendant claims that Dr. Cole’s testimony is necessary in this case because the reports could not be introduced through the government’s experts. .... However, the government has given every indication that its experts would recognize these reports, such that Defendant can use them on cross-examination. See Opp’n at 18 (“[t]o the extent the defendant wants to cross examine the [fingerprint] examiners on the basis of the empirical studies in which the error rates cited in the defendant’s motion were found, the defendant is free to do so....”). The Court finds that Dr. Cole’s testimony would not assist the trier of fact. See Pitts, 2018 WL 1169139, at *3. Accordingly, the testimony is precluded.

4. See David H. Kaye, On a “Ridiculous” Estimate of an “Error Rate for Fingerprint Comparisons”, Forensic Sci., Stat. & L., Dec. 10, 2016, http://for-sci-law.blogspot.com/2016/12/on-ridiculous-estimate-of-error-rate.html.
5. Federal Rule of Evidence 803(18); see generally David H. Kaye, David A. Bernstein, & Jennifer L. Mnookin, The New Wigmore: A Treatise on Evidence: Expert Evidence § 5.4 (2d ed. 2011).

Index to comments and cases on the PCAST report