Applying the Justice Department's Policy on a Reasonable Degree of Certainty in United States v. Hunt

In United States v. Hunt, \1/ Senior U.S. District Court Judge David Russell disposed of a challenge to proposed firearms-toolmark testimony. The first part of the unpublished opinion dealt with the scientific validity (as described in Daubert v. Merrell Dow Pharmaceuticals, Inc.) of the Association of Firearms and Toolmark Examiners (AFTE) "Theory of Identification As It Relates to Toolmarks." Mostly, this portion of the opinion is of the form: "Other courts have accepted the government's arguments. We agree." This kind of an opinion is common for forensic-science methods that have a long history of judicial acceptance--whether or not such acceptance is deserved.

The unusual part of the opinion comes at the end. There, the court misconstrues the Department of Justice's internal policy on the use of the phrase "reasonable certainty" to characterize an expert conclusion for associating spent ammunition with a gun that might have fired it. This posting describes some of the history of that policy and suggests that (1) the court may have unwittingly rejected it; (2) the court's order prevents the experts from expressing the same AFTE theory that the court deemed scientifically valid; and (3) the government can adhere to its written policy on avoiding various expressions of "reasonable certainty" and still try the case consistently with the judge's order.

I. The Proposed Testimony

Dominic Hunt was charged with being a felon is possession of ammunition recovered from two shootings. The government proposed to use two firearm and toolmark examiners--Ronald Jones of the Oklahoma City Police Department and Howard Kong of the Bureau of Alcohol, Tobacco, Firearms and Explosives' (ATF) Forensic Science Laboratory--to establish that the ammunition was not fired from the defendant's brother's pistol--or his cousin's pistol. To eliminate those hypotheses, "the Government intend[ed] its experts to testify" that "the unknown firearm was likely a Smith & Wesson 9mm Luger caliber pistol," and that "the probability that the ammunition ... were fired in different firearms is so small it is negligible."

This testimony differs from the usual opinion testimony that ammunition components recovered from the scene of a shooting came from a specific, known gun associated with a defendant. It appears that the "unknown" Luger pistol was never discovered and thus that the examiners could not use it to fire test bullets for comparison purposes. Their opinion was that several of the shell casings had marks and other features that were so similar that they must have come from the same gun of the type they specified.

But the reasoning process the examiners used to arrive at this conclusion--which postulates "class," "subclass," and conveniently designated "individual" characteristics--is the same as the one used in the more typical case of an association to a known gun. Perhaps heartened by several recent trial court opinions severely limiting testimony about the desired individualizing characteristics, Hunt moved "to Exclude Ballistic Evidence, or Alternatively, for a Daubert Hearing."

II. The District Court's Order

Hunt lost. After rejecting the pretrial objection to the scientific foundation of the examiners' opinions and the proper application of accepted methods by the two examiners, Judge Russell turned to the defendant's "penultimate argument [seeking] limitations on the Government's firearm toolmark experts." He embraced the government's response "that no limitation is necessary because Department of Justice guidance sufficiently limits a firearm examiner's testimony."

The odd thing is that he turned the Department's written policy on its head by embracing a form of testimony that the policy sought to eliminate. And the court did this immediately after it purported to implement DoJ's "reasonable" policy. The relevant portion of the opinion begins:

In accordance with recent guidance from the Department of Justice, the Government's firearm experts have already agreed to refrain from expressing their findings in terms of absolute certainty, and they will not state or imply that a particular bullet or shell casing could only have been discharged from a particular firearm to the exclusion of all other firearms in the world. The Government has also made clear that it will not elicit a statement that its experts' conclusions are held to a reasonable degree of scientific certainty.
The Court finds that the limitations mentioned above and prescribed by the Department of Justice are reasonable, and that the Government's experts should abide by those limitations. To that end, the Governments experts:

[S]hall not [1] assert that two toolmarks originated from the same source to the exclusion of all other sources.... [2] assert that examinations conducted in the forensic firearms/toolmarks discipline are infallible or have a zero error rate.... [3] provide a conclusion that includes a statistic or numerical degree of probability except when based on relevant and appropriate data.... [4] cite the number of examinations conducted in the forensic firearms/toolmarks discipline performed in his or her career as a direct measure for the accuracy of a proffered conclusion..... [5] use the expressions ‘reasonable degree of scientific certainty,’ ‘reasonable scientific certainty,’ or similar assertions of reasonable certainty in either reports or testimony unless required to do so by [the Court] or applicable law. \2/

So far it seems that the court simply told the government's experts (including the city police officer) to tow the federal line. But here comes the zinger. The court abruptly turned around and decided to ignore the Attorney General's mandate that DoJ personnel should strive to avoid expressions of "reasonable scientific certainty" and the like. The court wrote:

As to the fifth limitation described above, the Court will permit the Government's experts to testify that their conclusions were reached to a reasonable degree of ballistic certainty, a reasonable degree of certainty in the field of firearm toolmark identification, or any other version of that standard. See, e.g., U.S. v. Ashburn, 88 F. Supp. 3d 239, 249 (E.D.N.Y. 2015) (limiting testimony to a “reasonable degree of ballistics certainty” or a “reasonable degree of certainty in the ballistics field.”); U.S. v. Taylor, 663 F. Supp. 2d 1170, 1180 (D.N.M. 2009) (limiting testimony to a “reasonable degree of certainty in the firearms examination field.”). Accordingly, the Government's experts should not testify, for example, that “the probability the ammunition charged in Counts Eight and Nine were fired in different firearms is so small it is negligible” ***.

So the experts can testify that they have "reasonable certainty" that the ammunition was fired from the same gun, but they cannot say the probability that it was fired from a different gun is small enough that the alternative hypothesis has a negligible probability? Even though that is how experts in the field achieve "reasonable certainty" (according to the AFTE description that the court held was scientifically valid)? This part of the opinion hardly seems coherent. \3/

III. The Tension Between the Order and the ULTR

The two cases that the court cited for its "reasonable ballistic certainty" ruling were decided years before the ULTR that it called reasonable, and such talk of "ballistic certainty" and "any other version of that standard" is precisely what the Department had resolved to avoid if at all possible. The history of the "fifth limitation" has an easily followed paper trail that compels the conclusion that this limitation was intended to avoid precisely the kind of testimony that Judge Russell's order permits.

Let's start with the ULTR quoted (in part) by the court. It has a footnote to the "fifth limitation" that instructs readers to "See Memorandum from the Attorney General to Heads of Department Components (Sept. 9. 2016), https://www.justice.gov/opa/file/891366/download." The memorandum's subject is "Recommendations of the National Commission on Forensic Science; Announcement for NCFS Meeting Eleven." In it, Attorney General Loretta Lynch wrote:

As part of the Department's ongoing coordination with the National Commission on Forensic Science (NCFS), I am responding today to several NCFS recommendations to advance and strengthen forensic science. *** I am directing Department components to *** work with the Deputy Attorney General to implement these policies *** .

1. Department forensic laboratories will review their policies and procedures to ensure that forensic examiners are not using the expressions "reasonable scientific certainty" or "reasonable [forensic discipline] certainty" in their reports or testimony. Department prosecutors will abstain from use of these expressions when presenting forensic reports or questioning forensic experts in court unless required by a judge or applicable law.

The NCFS was adamant that judges should not require "reasonable [forensic discipline] certainty." Its recommendation to the Attorney General explained that

Forensic discipline conclusions are often testified to as being held “to a reasonable degree of scientific certainty” or “to a reasonable degree of [discipline] certainty.” These terms have no scientific meaning and may mislead factfinders about the level of objectivity involved in the analysis, its scientific reliability and limitations, and the ability of the analysis to reach a conclusion. Forensic scientists, medical professionals and other scientists do not routinely express opinions or conclusions “to a reasonable scientific certainty” outside of the courts. Neither the Daubert nor Frye test of scientific admissibility requires its use, and consideration of caselaw from around the country confirms that use of the phrase is not required by law and is primarily a relic of custom and practice. There are additional problems with this phrase, including:

• There is no common definition within science disciplines as to what threshold establishes “reasonable” certainty. Therefore, whether couched as “scientific certainty” or“ [discipline] certainty,” the term is idiosyncratic to the witness.
• The term invites confusion when presented with testimony expressed in probabilistic terms. How is a lay person, without either scientific or legal training, to understand an expert’s “reasonable scientific certainty” that evidence is “probably” or possibly linked to a particular source?

Accordingly, the NCFS recommended that the Attorney General "direct all attorneys appearing on behalf of the Department of Justice (a) to forego use of these phrases ... unless directly required by judicial authority as a condition of admissibility for the witness’ opinion or conclusion ... ." As we have seen, the Attorney General adopted this recommendation. \4/

IV. How the Prosecutors and the ATF Expert Can Follow Departmental Policy

Interestingly, Judge Russell's opinion does not require the lawyers and the witnesses to use the expressions of certainty. It "permits" them to do so (seemingly on the theory that this practice is just what the Department contemplated). But not all that is permitted is required. To be faithful to Department policy, the prosecution cannot accept the invitation. The experts can give their conclusion that the ammunition came from a single gun. However, they should not add, and the prosecutor may not ask them to swear to, some expression of "reasonable [discipline] certainty" because: (1) the Department's written policy requires them to avoid it "unless required by a judge or applicable law"; (2) the judge has not required it; and (3) applicable law does not require it. \5/

The situation could change if at the trial, Judge Russell were to intervene and to ask the experts about "reasonable certainty." In that event, the government should remind the court that its policy, for the reasons stated by the National Commission and accepted by the Attorney General, is to avoid these expressions. If the court then rejects the government's position, the experts must answer. But even then, unless the defense "opens the door" by cross-examining on the meaning of "reasonable [discipline] certainty," there is no reason for the prosecution to use the phrase in its examination of witnesses or closing arguments.

NOTES

1. No. CR-19-073-R, 2020 WL 2842844 (W.D. Okla. June 1, 2020).
2. The ellipses in the quoted part of the opinion are the court's. I have left out only the citations in the opinion to the Department's Uniform Language on Testimony and Reporting (ULTR) for firearms-toolmark identifications. That document is a jumble that is a subject for another day.
3. Was Judge Russell thinking that the "negligible probability" judgment is valid (and hence admissible as far as the validity requirement of Daubert goes) but that it would be unfairly prejudicial or confusing to give the jury this valid judgment? Is the court's view that "negligible" is too strong a claim in light of what is scientifically known? If such judgments are valid, as AFTE maintains, they are not generally prejudicial. Prejudice does not mean damage to the opponent's case that arises from the very fact that evidence is powerful.
4. At the NCFS meeting at which the Department informed the Commission that it was adopting its recommendation, "Commission member, theoretical physicist James Gates, complimented the Department for dealing with these words that 'make scientists cringe.'" US Dep't of Justice to Discourage Expressions of "Reasonable Scientific Certainty," Forensic Sci., Stat. & L., Sept. 12, 2016, http://for-sci-law.blogspot.com/2016/09/us-dept-of-justice-to-discourage.html.
5. In a public comment to the NCFS, then commissioner Ted Hunt (now the Department's senior advisor on forensic science) cited the "ballistic certainty" line of cases as indicative of a problem with the NCFS recommendation as then drafted but agreed that applicable law did not require judges to follow the practice of insisting on or entertaining expressions of certitude. See "Reasonable Scientific Certainty," the NCFS, the Law of the Courtroom," and That Pesky Passive Voice, Forensic Sci., Stat. & L., http://for-sci-law.blogspot.com/2016/03/reasonable-scientific-certainty-ncfs.html, Mar. 1, 2016; Is "Reasonable Scientific Certainty" Unreasonable?, Forensic Sci., Stat. & L., Feb. 26, 2016, http://for-sci-law.blogspot.com/2016/02/is-reasonable-scientific-certainty.html (concluding that

   In sum, there are courts that find comfort in phrases like "reasonable scientific certainty," and a few courts have fallen back on variants such as "reasonable ballistic certainty" as a response to arguments that identification methods cannot ensure that an association between an object or person and a trace is 100% certain. But it seems fair to say that "such terminology is not required " -- at least not by any existing rule of law.)