Saturday, July 9, 2022

Preliminary Results from a Blind Quality Control Program

The Houston Forensic Science Center recently reported the results of realistic, blind tests of its firearms examiners. Realism comes from disguising materials to look like actual casework and injecting these "mock evidence items" into the regular flow of business. The judgments of the examiners for the mock cases can be evaluated with respect to the true state of affairs (ammunition components from the same firearm as opposed to components from different firearms). Eagerly, I looked for a report of how often the examiners declared an association for pairs of items that were not associated with one another (false "identifications") and how often they declared that there was no association for pairs that were in fact associated (false "eliminations").

These kinds of conditional "error rates" are by no means all there is to quality control and to improving examiner performance, which is the salutary objective of the Houston lab, but they are prominent in judicial opinions on the admissibility of firearms-toolmark evidence. So too, they (along with the cognate statistics of specificity and sensitivity) are established measures of the validity of tests for the presence or absence of a condition. Yet, I searched in vain for clear statements of these standard measures of examiner performance in the article by Maddisen Neuman, Callan Hundl, Aimee Grimaldi, Donna Eudaley, Darrell Stein and Peter Stout on "Blind Testing in Firearms: Preliminary Results from a Blind Quality Control Program," 67(3) J. Forensic Sci. 964-974 (2022).

Instead, tables use a definition of "ground truth" that includes materials being intentionally "insufficient" or "unsuitable" for analysis, and they focus on whether "[t]he reported results either matched the ground truth or resulted in an inconclusive decision." (Here, "inconclusive" is different from insufficient" and "unsuitable." For the sake of readers who are unfamiliar with firearms argot, Table 1 defines--or tries to--the terminology for describing the outcomes of the mock cases.)

TABLE 1. Statements for the Outcome of an Examination
(adapted from p. 966 tbl. 1)

Binary (Yes/No) Source Conclusions

Identification: A sufficient correspondence of individual characteristics will lead the examiner to the conclusion that both items (evidence and tests) originated from the same source.
Elimination: A disagreement of class characteristics will lead the examiner to the conclusion that the items did not originate from the same source. In some instances, it may be possible to support a finding of elimination even though the class characteristics are similar when there is marked disagreement of individual characteristics.
Statements of No Source Conclusion

Unsuitable: A lack of suitable microscopic characteristics will lead the examiner to the conclusion that the items are unsuitable for identification.
Insufficient: Examiners may render an opinion that markings on an item are insufficient when:
• an item has discernible class characteristics but no individual characteristics
• an item does not exhibit class characteristics and has few individual characteristics of such poor quality that precludes an examiner from rendering an opinion;
• the examiner cannot determine if markings on an item were made by a firearm during the firing process; or
• the examiner cannot determine if markings are individual or subclass.
Inconclusive: An insufficient correspondence of individual and/or class characteristics will lead the examiner to the conclusion that no identification or elimination could be made with respect to the items examined.
Note on "identification": The identification of cartridge case/bullet toolmarks is made to the practical, not absolute, exclusion of all other firearms. This is because it is not possible to examine all firearms in the world, a prerequisite for absolute certainty. The conclusion that sufficient agreement for identification exists between toolmarks means that the likelihood that another firearm could have made the questioned toolmarks is so remote as to be considered a practical impossibility.

There were 51 mock cases containing anywhere from 2 to 41 items (median = 9). In the course of the five-and-a-half year study, 460 items were examined for a total of 570 judgments by only 11 firearms examiners, with experience ranging from 5.5 to 23 years. The mock evidence varied greatly in its informativeness, and the article suggests that the lab sought to use a greater proportion of challenging cases than might be typical.

Whether or not the study is generalizable to other examiners, laboratories, and cases, the authors write that "no hard errors were observed; that is, no identifications were declared for true nonmatching pairs, and no eliminations were declared for true matching pairs." This sounds great, but how probative is the observation of "no hard errors"

Table 3 of the article states that there were 143 false pairs, of which 106 were designated inconclusive. It looks like the examiners were hesitant to make an elimination, even for a false pair. They made only 37 eliminations. Since there were no "hard errors," none of the false pairs were misclassified as identifications. Ignoring inconclusives, which are not presented as evidence for or against an association, the observed false-identification rate therefore was 0/37. Using the rule of three for a quick approximation, we can estimate the 95% confidence interval as going from 0 to 3/37. To use phrasing like that in the 2016 PCAST Report, the false-positive rate could be as large as 1 in 9.

Applying the same reasoning to the 386 true pairs, of which 119 were designated inconclusive, the observed false-elimination rate must have been 0/267. The 95% confidence interval for the false-elimination rate thus extends to about 3/267, or 1/89.

These confidence intervals should not be taken too seriously. The simple binomial probability model implicit in the calculations does not hold for dependent comparisons. To quote the authors (p. 968), "Because the data were examined at the comparison level, an item of evidence can appear in the data set in multiple comparisons and be represented by multiple comparison conclusions. For example, Item 1 may have been compared to Item 2 and Item 3 with comparison conclusions of elimination and identification, respectively." Moreover, I could be misconstruing the tables. Finally, even if the numbers are all on target, they should not taken as proof that error rates are as high as the upper confidence limits. The intervals are merely indications of the uncertainty in using particular numbers as estimates of long-term error rates.

In short, the "blind quality control" program is a valuable supplement to minimal-competency proficiency testing. The absence of false identifications and false eliminations is encouraging, but the power of this study to pin down the probability of errors at the Houston laboratory is limited.

Wednesday, July 6, 2022

Why Did the Proposed Amendment to Rule 702 Scuttle the "Preponderance of the Evidence"?

After posting a description of the changes to the proposed amendment to Federal Rule of Evidence 702, I received the following inquiry:

Which one is actually the proposal? "More likely than not" or "by a preponderance of the evidence"? The former seems to be a weakening, the latter (even if it is redundant for lawyers) puts forensic scientists on notice. Use of the word "evidence" in the latter is, however, potentially confusing. "Evidential reliability" is about the "reliability" [sic] of the "evidence", i.e., the "scientific validity" of the methods applied to arrive at the "opinion". The proposed change (if it is the proposed change) seems to refer to "evidence" about the "reliability" of the "evidence" (in which the first and second instance of the word "evidence" do not refer to the same thing).

The first iteration of the amendment used "preponderance." It read, "[a]n [expert] witness ... may testify ... if the proponent has demonstrated by a preponderance of the evidence that" the proposed evidence satisfies various requirements regarding what the Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), called "evidentiary reliability." Now the proposed text is, "An [expert] witness ... may testify ... if the proponent demonstrates to the court that it is more likely than not that" the proposed evidence satisfies these requirements.

Why the change? Partly because of the elliptical nature of the original formulation and partly because of the awkwardness of the construction "evidence that the evidence." As the rest of this posting explains, the new (green) version is better drafted, but the idea was never in doubt.

The governing principle comes from Federal Rule of Evidence 104(a) as interpreted in Bourjaily v. United States, 483 U.S. 171 (1987). The rule begins with a general observation that

The court must decide any preliminary question about whether a witness is qualified, a privilege exists, or evidence is admissible. In so deciding, the court is not bound by evidence rules, except those on privilege.

Fed. R. Evid. 104(a). So to decide whether proffered evidence is admissible at trial, the court can consider all pertinent, non-privileged information presented to it, whether or not the information about admissibility would be admissible in a trial.

But Rule 104 is silent on how confident the judge should be that the proposed evidence satisfies the requirements for admissibility. That is where Bourjaily comes in. In that case, the government wanted to introduce out-of-court statements of a coconspirator as evidence against the defendant. To avoid the rule against hearsay, it sought to persuade the court to apply the rule that certain statements of conspirators are admissible against everyone in the conspiracy. Defendant's membership in the conspiracy was thus a preliminary question for the court, and the Bourjaily Court explained that

We are ... guided by our prior decisions regarding admissibility determinations that hinge on preliminary factual questions. We have traditionally required that these matters be established by a preponderance of proof. Evidence is placed before the jury when it satisfies the technical requirements of the evidentiary Rules, which embody certain legal and policy determinations. The inquiry made by a court concerned with these matters is not whether the proponent of the evidence wins or loses his case on the merits, but whether the evidentiary Rules have been satisfied. Thus, the evidentiary standard is unrelated to the burden of proof on the substantive issues, be it a criminal case ... or a civil case. ... The preponderance standard ensures that, before admitting evidence, the court will have found it more likely than not that the technical issues and policy concerns addressed by the Federal Rules of Evidence have been afforded due consideration. ... Therefore, we hold that, when the preliminary facts relevant to Rule 801(d)(2)(E) are disputed, the offering party must prove them by a preponderance of the evidence.

483 U.S. at 175-76 (note omitted).

Applying Bourjaily to the preliminary questions in Rule 702, it is quite clear that the trial court has to find that "evidentiary reliability" under Rule 702 is more probable than not. To foreclose any debate about it, in Daubert itself, the Court pointed to the preponderance standard, writing that "[f]aced with a proffer of expert scientific testimony, then, the trial judge must determine at the outset, pursuant to Rule 104(a), whether the expert is proposing to testify to (1) scientific knowledge that (2) will assist the trier of fact to understand or determine a fact in issue." 509 U.S. at 592.

Yet, many public commenters did not see this. Some comments claimed that the word "evidence" in "preponderance of the evidence" would constrain the court to considering only such evidence as would be admissible at trial in deciding whether the proposed expert testimony is admissible. Other comments claimed that the phrase would keep previously admissible evidence from juries. Indeed, "almost all of the fire was directed toward the term 'preponderance of the evidence.'” Advisory Comm. on Evid. Rules, Report to the Standing Committee, May 15, 2022, at 7.

The Advisory Committee unabashedly rejected both these claims. In its report to the Standing Committee, it wrote that:

The Committee does not agree that the preponderance of the evidence standard would limit the court to considering only admissible evidence; the plain language of Rule 104(a) allows the court deciding admissibility to consider inadmissible evidence. Nor did the Committee believe that the use of the term preponderance of the evidence would shift the factfinding role from the jury to the judge, for the simple reason that, when it comes to making preliminary determinations about admissibility, the judge is and always has been a factfinder.

Id. Nevertheless,

[T]he Committee recognized that it would be possible to replace the term “preponderance of the evidence” with a term that would achieve the same purpose while not raising the concerns (valid or not) mentioned by many commentators. The Committee unanimously agreed to change the proposal as issued for public comment to provide that the proponent must establish that it is “more likely than not” that the reliability requirements are met. This standard is substantively identical to “preponderance of the evidence” but it avoids any reference to “evidence” and thus addresses the concern that the term “evidence” means only admissible evidence.

Id. Finally,

The Committee was also convinced by the suggestion in the public comment that the rule should clarify that it is the court and not the jury that must decide whether it is more likely than not that the reliability requirements of the rule have been met. Therefore, the Committee unanimously agreed with a change requiring that the proponent establish “to the court” that it is more likely than not that the reliability requirements have been met. The proposed Committee Note was amended to clarify that nothing in amended Rule 702 requires a court to make any findings about reliability in the absence of a proper objection.

Id. Overlooked in this debate over the niceties of the phrase "preponderance of the evidence" is a different drafting point. The proposed amendment makes it explicit that the standard pertains to the court's role in considering scientific validity, but it does not do the same for the other requirements of Rule 702--namely, that the witness be "qualified as an expert by knowledge, skill, experience, training, or education." That a witness is qualified to testify also must be established as more probable than not. For a rare case excluding testimony from a latent fingerprint examiner because she ran into problems in demonstrating proficiency, see United States v. Cloud, No. 1:19-cr-02032-SMJ-1, 2021 WL 7184484 (E.D. Wash. Dec. 17, 2021) (false exclusion in casework, a false exclusion on a proficiency test, and receiving help from her supervisor on a follow-up proficiency test).

Friday, July 1, 2022

Proposed Amendment to Federal Rule of Evidence 702 Clears More Hurdles

The following report appeared in the OSAC newsletter OSAC In Brief, June 2022, at 4-6 with the title "Proposed Amendment to Federal Rule of Evidence 702 Clears More Hurdles." It updates a report in the June 2022 issue (posted earlier today on this blog). Both reports are meant to be boringly factual. More opinionated remarks may appear later.

After five years of discussion, a proposed amendment to Federal Rule of Evidence 702 on testimony by expert witnesses has progressed to the Judicial Conference of the United States—the policy-making arm of the federal judiciary. If the Judicial Conference accepts the unanimous recommendations of both its Advisory Committee on Evidence Rules, which drafted the amendment, and its standing Committee on Rules of Practice and Procedure, which endorsed it this month, the amendment will be delivered to the Supreme Court for transmittal to Congress. Then, unless Congress intervenes, it will become effective by the end of next year.

But what effect would it have? According to the Advisory Committee chair, U.S. District Court Judge Patrick Schiltz, the amendment does not alter the meaning of the rule in the slightest. “It simply makes it clearer, makes it easier for people to understand, so that fewer mistakes will be made” (as reported June 7, in Bloomberg Law). Box 1 shows the proposed changes, which differ slightly from those discussed in the OSAC In Brief article of July 2021.

BOX 1. Proposed Changes to Federal Rule of Evidence 702
A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that:
(a) the expert's scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied expert's opinion reflects a reliable application of the principles and methods to the facts of the case.

On the face of it, the amendment does little, if anything, to alter the substance of the existing rule. It adds the words “if the proponent demonstrates to the court that it is more likely than not” in front of the criteria for admitting expert testimony, but the Supreme Court had already noted that in exercising a longstanding “gatekeeping” role, the district court needs to determine whether the conditions for admitting expert testimony are “established by a preponderance of proof.” (Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579, 592 n.10 (1993) (citing Fed. Evid. 104(a); as a result of public comments, the Advisory Committee substituted “more likely than not” for the “preponderance of evidence” to describe the proponent’s burden of persuasion on the issue of admissibility).

The other wording change concerns the well entrenched reliability-as-applied requirement (“the expert has reliably applied” in part (d)). The amendment uses an alternative phrase—“the expert's opinion reflects a reliable application.” Although one could argue that the specific reference to “opinion” limits the requirement to personal opinions, that is not the intent. An explanatory note that will accompany the revised rule (if and when it is adopted) makes it plain that it still must appear that the expert has applied a valid and reliable method proficiently and appropriately in making any and all findings and inferences. The only purpose of the change is “to emphasize that each expert opinion must stay within the bounds of what can be concluded from a reliable application” of a reliable method to the facts of the case. And, this Advisory Committee Note (ACN) adds that this directive is “is especially pertinent to the testimony of forensic experts,” for which “the judge should (where possible) receive an estimate of the known or potential rate of error of the methodology employed, based (where appropriate) on studies that reflect how often the method produces accurate results” rather than “assertions of absolute or one hundred percent certainty—or to a reasonable degree of scientific certainty ... .”

During the six-month comment period that ended in February, the draft received well over 500 comments. The Reporter to the Advisory Committee found the public reaction “somewhat surprising, because the proposed amendment essentially seeks only to clarify the application of Rule 702 as it was amended in 2000—and that amendment received [only] 179 comments.” Lawyers from the plaintiffs’ side of the civil bar opposed the latest amendment, while defendants’ lawyers supported it.

There were relatively few comments about the implications of the additional words and the accompanying note for the areas of forensic science covered by OSAC. These too were (predictably) divided. The National District Attorneys Association (NDAA) objected to the ACN’s singling out forensic-science testimony as a problem and saw the amendments as “a solution in search of a problem.” But the New York City Bar Association expressed “particular concern [with] criminal prosecutions” and “the scientific validity of many types of ‘feature-comparison’ methods of identification, such as those involving fingerprints, footwear and hair.” The New York State Crime Laboratory Advisory Committee (NYSCLAC) objected to “changes limiting forensic science testimony” but then maintained that its laboratories already complied with the guidance in the ACN. The Union of Concerned Scientists questioned parts of the NDAA and NYSCLAC statements and insisted that “forensic evidence should be required to present courts with estimates of error rates relevant to their methodologies.” The Innocence Project and other organizations and individuals submitted a joint statement praising the changes and pressing for more. They wanted the text of the rule to contain a requirement that testimony is not only “the product of reliable principles and methods” (the current wording), but also to specify that it “includes the limitations and uncertainty of those principles and methods.”

The conflicting comments regarding forensic science produced no modifications. If the amendment is adopted, it will implement, to some extent, the 2016 recommendation of the President’s Council of Advisors on Science and Technology that “the Judicial Conference of the United States ... should prepare ... an Advisory Committee note, providing guidance to Federal judges concerning the admissibility under Rule 702 of expert testimony based on forensic feature-comparison methods.”

Author’s disclaimer: This report presents the views of the author. Their publication in In Brief is not an endorsement by NIST or OSAC, and they are not intended to represent the views of any OSAC unit. No estimate of the known or potential rate of error is available.

Proposed Changes to Federal Rule of Evidence 702

The following report appeared in the OSAC newsletter OSAC In Brief, July 2021, at 3-7 with the uninspired title "Proposed Changes to Federal Rule of Evidence 702." It was followed by an update in the June 2022 issue (about to be reproduced on this blog). Both are meant to be boringly factual. More opinionated remarks may appear later.

On April 30, the federal Advisory Committee on Evidence Rules unanimously proposed two changes to the wording of Federal Rule of Evidence 702. The rule, which many states have adopted in one form or another, provides for testimony by expert witnesses. The changes do not alter the meaning of the rule, but they can be seen as a course-correction signal telling courts to be more vigorous in ensuring that “forensic expert testimony is valid, reliable, and not overstated in court.”

The quoted words come from a report of the Advisory Committee. Facilitating such testimony also is part of OSAC’s raison d’ĂȘtre. This article for In Brief therefore describes the proposed amendment, a little bit of its history, the steps required for it to be enacted into law, and its significance for OSAC’s work.

The Proposer: An Advisory Committee to the Standing Committee of the Judicial Conference

The Judicial Conference of the United States is the policymaking organ of the judicial branch of the federal government. Composed of the Chief Justice of the U.S. Supreme Court, the chief judges of the 13 federal judicial circuits, and select federal district judges, it also is required by statute “to carry on a continuous study of the operation and effect of the general rules of practice and procedure" that apply in the federal courts (and, with some variations, in many state court systems as well). The Conference relies on a “Committee on Rules of Practice and Procedure, commonly referred to as the ‘Standing Committee.’" The Standing Committee, in turn, relies on advisory committees on appellate, bankruptcy, civil, criminal, and evidence rules. These advisory committees are comprised of “federal judges, practicing lawyers, law professors, state chief justices, and representatives of the Department of Justice.” (Quotations are from the Administrative Office of the U.S. Courts.) The Advisory Committee on Evidence Rules (which we can abbreviate as ACER) is one of these committees.

The Proposed Text: Two Wording Changes

Rule 702 went into effect in federal courts in 1975. It was one sentence long. The Supreme Court famously interpreted it in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993), a somewhat ambivalent and abstract opinion. The Court expounded further in cases in 1997 and 1999. The rule was rewritten to incorporate the teachings in these cases in 2000, leading to the version with the longer sentence in the right-hand side of Box 1.

BOX 1. FEDERAL RULE OF EVIDENCE 702 THEN AND NOW
The Rule in 1975 The Rule in 2021
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise. A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if:
(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied the principles and methods to the facts of the case.

The proposed amendment makes two seemingly minor changes, shown in Box 2:

BOX 2. THE ADVISORY COMMITTEE’S PROPOSED AMENDMENT TO RULE 702

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent has demonstrated by a preponderance of the evidence that:
(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;
(b) the testimony is based on sufficient facts or data;
(c) the testimony is the product of reliable principles and methods; and
(d) the expert has reliably applied expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.

Reading these words, one might well ask what is going on. The first change seems to state the obvious (to lawyers, anyway). A footnote in Daubert already indicates that in the “preliminary assessment of whether the reasoning or methodology” possesses “evidentiary reliability,” the trial court must be satisfied by “a preponderance of proof” because that is the threshold for all “[p]reliminary questions concerning the qualification of a person to be a witness, the existence of a privilege, or the admissibility of evidence.” It may not hurt to state this standard in the text of the rule (although including it after the opening clause about qualifications awkwardly fails to modify the qualifications part of the rule). But why bother?

Similarly, the change to Part (d) is potentially confusing because it limits the “reliable application” prong of the rule to expert “opinion” even though, as the Advisory Committee that drafted the original rule noted, it is “logically unfounded” to “assume[] that experts testify only in the form of opinions.” Instead, “[t]he rule … recognizes that an expert on the stand may give a dissertation or exposition of scientific or other principles relevant to the case, leaving the trier of fact to apply them to the facts.” But aside from the probably unintended limitation of the as-applied prong to opinions, why bother? What is the difference between testimony when an expert has “reasonably applied the principles and methods” and testimony that “reflects a reasonable application of the principles and methods”?

The answers lie in ACER’s official note prepared to accompany the rule, the minutes of its meetings, and its periodic reports to the Standing Committee on its progress in revising the rule.

The Purpose of the New Text

For OSAC, the most salient parts of the note of the Advisory Committee are in Boxes 3 and 4. As to the first change, regarding “preponderance,” ACER believed that

BOX 3. Part of ACER’s Proposed Note Explaining Its First Proposed Change

[M]any courts have held that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility. These rulings are an incorrect application of Rules 702 and 104(a). … The Committee concluded that emphasizing the preponderance standard in Rule 702 specifically was made necessary by the courts that have failed to apply correctly the reliability requirements of that rule. … [Explicitly incorporating the standard] means that once the court has found the admissibility requirement to be met by a preponderance of the evidence, any attack by the opponent will go only to the weight of the evidence.

A major push for this change came from individuals and organizations concerned with civil litigation in which, they believed, courts have admitted expert opinions that a drug or chemical is harmful without adequately verifying that there is a body of scientific literature sufficient to let a reasonable expert conclude that the substance can cause the kind of harm claimed to have occurred under the conditions of the case. However, it also will remind judges in criminal cases that they must have proof that the scientific literature is sufficient to support the findings of forensic-science experts.

As Box 4 shows, the second part of the “amendment is especially pertinent to the testimony of forensic [science] experts in both criminal and civil cases”:

BOX 4. Part of ACER’s Proposed Note Explaining Its Second Proposed Change

Rule 702(d) has also been amended to emphasize that a trial judge must exercise gatekeeping authority with respect to the opinion ultimately expressed by a testifying expert. … The amendment is especially pertinent to the testimony of forensic experts in both criminal and civil cases. Forensic experts should avoid assertions of absolute or one hundred percent certainty—or to a reasonable degree of scientific certainty—if the methodology is subjective and thus potentially subject to error. In deciding whether to admit forensic expert testimony, the judge should (where possible) receive an estimate of the known or potential rate of error of the methodology employed, based (where appropriate) on studies that reflect how often the method produces accurate results. Expert opinion testimony regarding the weight of feature comparison evidence (i.e., evidence that a set of features corresponds between two examined items) must be limited to those inferences that can reasonably be drawn from a reliable application of the principles and methods. This amendment does not, however, bar testimony that comports with substantive law requiring opinions to a particular degree of certainty. … [N]othing in the amendment requires the court to nitpick an expert’s opinion in order to reach a perfect expression of what the basis and methodology can support. The … standard does not require perfection. On the other hand, it does not permit the expert to make extravagant claims that are unsupported by the expert’s basis and methodology.

It is the ACER note, much more than the revisions to the text of the rule, that has implications for forensic-science evidence. As the note indicates, the committee was especially concerned with forensic-science testimony. Its briefing materials included summaries of federal cases from across the spectrum of forensic sciences that raised the issue of “overstatement.” Furthermore, the idea of a new Advisory Committee Note came from the 2016 report of the President’s Council of Advisors on Science and Technology. PCAST called on “the Judicial Conference [to] prepare, with advice from the scientific community, a best practices manual and an Advisory Committee note, providing guidance to Federal judges concerning the admissibility under Rule 702 of expert testimony based on forensic feature-comparison methods.”

Apparently, PCAST did not realize that ACER is not empowered to write new notes to old rules. At a symposium convened by ACER in 2017, PCAST co-chair and newly appointed Presidential science advisor, Eric Lander, advised the committee as follows: “If an advisory note is a possibility, I’d favor it. If it’s not, change a comma in the rule and then write a new advisory note. Change one word, any word and write an advisory note.” Advisory Comm. on Evid. Rules Symposium on Forensic Expert Testimony, Daubert, and Rule 702, 86 Ford. L. Rev. 1463, 1523 (2018). This change-a-word artifice is more or less what is happening.

What Is Next in the Rulemaking Process?

The proposed amendment is just that—proposed. To become law, the ACER amendment and accompanying note must be approved by the Standing Committee after a six-month period for public comment and testimony (after which ACER reviews and can revise the proposed amendment and seek more comment). The Standing Committee then reviews the final drafts. It can revise and return the draft to ACER, or it can submit the amendment and note to the full Judicial Conference for its review. If the Judicial Conference approves, the drafts go to the Supreme Court, which normally transmits them to Congress with no substantive review. Congress then can adopt, reject, modify, or defer the rule change, but if Congress is silent for seven months, the amendment becomes effective at the end of the year.

Plainly, the proposal, which was four years in the making, still has a long way to go, but the very fact that ACER deliberated at length and expressed concern about forensic-science testimony, overstatement, and error probabilities could have more immediate impact in litigation.

Implications for OSAC

To help satisfy the proof requirements of Rule 702 (both as it stands and as it might be amended), subcommittees drafting standards for making findings and for reporting or testifying should specifically cite the scientific literature that supports each part of the standard. Valid estimates of potential error rates (or related statistics on the accuracy of results), or procedures to arrive at these estimates, should be part of such standards. Scientific and Technical Review Panels (STRPs) already are instructed to look for this content or for an explanation in the standard of why methods for ascertaining and expressing uncertainty in measurements, observations, or inferences are not present in the standards they review.

The repeated references to “overstatement” in ACER’s deliberations and materials should reinforce the desire of OSAC units to address the admittedly difficult problem of prescribing standards for testimony—and to use phrases in all standards that involve results that will satisfy the insistence on “those inferences that can reasonably be drawn from a reliable application of the principles and methods.” Cases on firearms-toolmark identifications (called “ballistics” cases in the ACER materials) suggest that judicial efforts are unlikely to produce the best solution. The Department of Justice has attempted to confront this issue with its Uniform Language for Testimony and Reports standards (ULTRs). It argued to ACER that these ULTRs help solve the problem of overclaiming, but one response was that because there are no such standards in laboratories generally, a new Advisory Committee Note is necessary. OSAC units still can help fill this gap if they act quickly.

Disclaimer: This report presents the views of the author. Their publication in In Brief is not an endorsement by NIST or OSAC, and they are not intended to represent the views of any OSAC unit. The error rate associated with them is not known.