Court Opinion

ID: 9382014
Source: CourtListenerOpinion
Date Created: 2023-03-24 16:00:44.410492+00
Date Added: 2024-06-11T17:17:36.475119
License: Public Domain

Appellate Case: 21-6046     Document: 010110832100        Date Filed: 03/24/2023     Page: 1
                                                                                    FILED
                                                                        United States Court of Appeals
                                        PUBLISH                                 Tenth Circuit

                       UNITED STATES COURT OF APPEALS                          March 24, 2023

                                                                           Christopher M. Wolpert
                              FOR THE TENTH CIRCUIT                            Clerk of Court
                          _________________________________

  UNITED STATES OF AMERICA,

        Plaintiff - Appellee,

  v.                                                            No. 21-6046

  DOMINIC EUGENE HUNT, a/k/a Dime
  Sack,

        Defendant - Appellant.
                       _________________________________

                      Appeal from the United States District Court
                         for the Western District of Oklahoma
                             (D.C. No. 5:19-CR-00073-R-1)
                        _________________________________

 Grant R. Smith, Assistant Federal Public Defender (Virginia L. Grady, Federal Public
 Defender, with him on the briefs), Denver, Colorado, for Defendant-Appellant.

 Jacquelyn M. Hutzell, Assistant United States Attorney (Robert J. Troester, United States
 Attorney, and David McCrary, Assistant United States Attorney, with her on the brief),
 Oklahoma City, Oklahoma, for Plaintiff-Appellee.
                        _________________________________

 Before HARTZ, SEYMOUR, and MORITZ, Circuit Judges.
                   _________________________________

 HARTZ, Circuit Judge.
                          _________________________________

       Defendant Dominic Eugene Hunt appeals his convictions on two charges of being

 a felon in possession of ammunition. The ammunition was used in two shootings in early

 2019. Investigators found three spent cartridges at the scene of one shooting and one
Appellate Case: 21-6046      Document: 010110832100          Date Filed: 03/24/2023       Page: 2

 spent cartridge at the other. A firearms expert testified that all four cartridges were fired

 from the same (undiscovered) weapon. Defendant’s sole complaint on appeal is that the

 expert testimony should not have been admitted at trial. He argues that the expert’s field

 of firearm toolmark examination is not scientifically valid and that the district court failed

 to perform its gatekeeping role in examining the admissibility of expert testimony

 because it relied on prior judicial opinions rather than the most up-to-date empirical

 evidence when it denied his pretrial motion to exclude the testimony without conducting

 a hearing.

        Exercising jurisdiction under 28 U.S.C. § 1291, we affirm. We need not declare a

 general rule on the admission of firearm toolmark testimony. We hold only that the

 district court adequately performed its gatekeeping role and did not err in admitting the

 testimony in light of the material presented on the pretrial motion and the expert

 testimony at trial.

        I.     BACKGROUND

        On January 20, 2019, a car was stolen from the residence of Defendant’s

 cousin, Jimmy Jones. The theft was captured on the surveillance camera at Jones’s

 home. It showed that after his daughter started her car to warm it up and went back

 inside, a man exited a blue Hyundai that had driven by and then jumped in her car

 and drove off following the Hyundai. Jones later thought he saw the same blue

 Hyundai down the street, though it turned out that he was mistaken. Based on this

 misidentification, however, he, Defendant, Travis Carter (Jones’s brother), and

 Christopher Dawson (Defendant’s brother) confronted three men that Jones thought

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 were involved in the theft. This confrontation led to a fistfight, which ended when

 someone shot Del Lavar Brison, one of the men from the group that Defendant

 confronted. An officer with the Oklahoma City Police Department (OCPD) was

 called to the scene and asked Brison who shot him. Brison said something that the

 responding officer understood as indicating that “it was a black male wearing a . . .

 maroon jacket.” R., Vol. III at 213. The surveillance video from Jones’s home

 showed Defendant wearing a maroon hoodie at the time of the theft. An OCPD

 crime-scene investigator recovered one spent Blazer 9mm Luger cartridge case from

 the scene—it was the only cartridge case that was found.

          Less than two weeks later, in the early morning of February 2, 2019, a man

 named Conilius Wright was found unconscious in his truck after being mortally

 wounded in a drive-by shooting. One of Wright’s companions testified that

 Defendant and Wright had issues with one another, and Defendant’s then girlfriend

 testified that on the night of the shooting Wright spoke with her about possibly being

 the father of her child. Defendant’s cell-phone location data indicated that he was

 near Wright’s shooting one minute before it was reported on a 911 call. An OCPD

 crime-scene investigator recovered three spent cartridge cases near Wright’s vehicle:

 one Blazer 9mm Luger cartridge case and two Winchester 9mm Luger cartridge

 cases.

          The four 9mm Luger cartridge cases recovered from the January and February

 2019 incidents were submitted to the OCPD Firearms Laboratory and were analyzed

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 by Ronald Jones, a firearm and toolmark1 examiner. Jones compared the cases using

 a microscope and reported on November 4, 2019, that (1) the three cartridge cases

 recovered at the scene of Wright’s homicide were all fired from the same unknown

 firearm and (2) that same unknown firearm fired the one cartridge case recovered

 from the scene of Brison’s shooting.

       On November 6, 2019, a federal grand jury returned a nine-count third

 superseding indictment against Defendant. The first seven counts arose from

 Defendant’s unlawful possession of a firearm and drug-trafficking activities five

 years before the shooting. This appeal concerns only the last two counts. Count 8

 charged that Defendant violated 18 U.S.C. § 922(g)(1) by being a felon in possession

 of ammunition—the Blazer 9mm Luger cartridge case recovered from the scene of

 the January 2019 incident. Count 9, which was added in the third superseding

 indictment, charged that Defendant violated the same provision in February 2019 by

 possessing the one Blazer 9mm Luger cartridge case and two Winchester 9mm Luger

 cartridge cases recovered from the scene of Wright’s homicide.

       After the government disclosed that it intended to present firearms-expert

 testimony to show that the spent cartridge cases recovered from the January and

 February incidents were fired from the same gun, Defendant filed in March 2020 his

       1
          “Toolmarks are generated when a hard object (tool) comes into contact with a
 relatively softer object. Such toolmarks may occur in the commission of a crime
 when an instrument such as a screwdriver, crowbar, or wire cutter is used or when the
 internal parts of a firearm make contact with the brass and lead that comprise
 ammunition.” Nat’l Rsch. Council, Strengthening Forensic Science in the United
 States: A Path Forward 150 (2009).
                                           4
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 “Motion in Limine to Exclude Ballistics Evidence, or, Alternatively, for a Daubert

 Hearing.” R., Vol. I at 106.

       Before our discussion of the arguments advanced in Defendant’s motion to

 exclude the firearms-expert testimony, an overview of firearm toolmark examination

 is in order. The method of comparing marks left on different pieces of ammunition to

 determine whether the ammunition was expended from the same firearm has been

 used for over a century. See, e.g., Commonwealth v. Best, 62 N.E. 748, 750 (Mass.

 1902) (Holmes, C.J.) (rejecting a challenge to the admission of an expert’s firearms-

 identification testimony). While advances in science and technology have refined the

 field of firearm toolmark examination, its object remains the same: “to determine

 whether ammunition is or is not associated with a specific firearm based on toolmarks

 produced by guns on the ammunition.” President’s Council of Advisors on Sci. and

 Tech., Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-

 Comparison Methods 104 (2016) [hereinafter PCAST Report]. The underlying

 concept is that different equipment and processes used in manufacturing firearms

 produce unique marks on the internal parts of the firearm. Firearm examiners theorize

 that even the same manufacturing tool will produce “microscopically different”

 marks on consecutively produced firearms, since “[m]anufacturing tools experience

 wear and abrasion as they cut, scrape, and otherwise shape metal.” Nat’l Rsch.

 Council, Strengthening Forensic Science in the United States: A Path Forward 150

 (2009) [hereinafter NRC Report]. Also, the internal parts of the firearm may undergo

 individualized changes through use. Firearm toolmarks are then produced “when the

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 internal parts of a firearm make contact with the brass and lead that comprise

 ammunition.” Id. Specifically with respect to cartridge cases (which house the

 primer, gunpowder, and bullet):2

        The brass exterior of cartridge cases receive[s] . . . toolmarks during the
        process of gun firing: the firing pin dents the soft primer surface at the
        base of the cartridge to commence firing, the primer area is forced
        backward by the buildup of gas pressure (so that the texture of the gun’s
        breech face is impressed on the cartridge), and extractors and ejectors
        leave marks as they expel used cartridges and cycle in new ammunition.

 Id. at 151.

        The experts in this case used the Association of Firearms and Tool Mark

 Examiners (AFTE) method to compare the toolmarks left on the four cartridge cases.

 See United States v. Hunt, 464 F. Supp. 3d 1252, 1256 (W.D. Okla. 2020). Under this

 method, examiners begin by evaluating class characteristics, “which are features that

 are permanent and predetermined before manufacture.” PCAST Report at 104. They

 are “family resemblances which will be present in all weapons of the same make and

        2
          At oral argument Defendant’s appellate counsel suggested for the first time
 that the district court erred to the extent that it found firearm toolmark examination
 reliable based on studies involving toolmarks left on bullets (as opposed to cartridge
 cases). We decline to consider this argument. See United States v. Malone, 10 F.4th
 1120, 1124–25 (10th Cir. 2021) (“[I]ssues may not be raised for the first time at oral
 argument.” (internal quotation marks omitted)). We note, however, that while the
 processes that transfer toolmarks to bullets are not the same as those leaving marks
 on cartridge cases, see NRC Report at 151, the examinations of each “involve[] many
 of the same concepts,” United States v. Williams, 506 F.3d 151, 158 n.4 (2d Cir.
 2007); see also Alfred Biasotti, John Murdock & Bruce R. Moran, Introductory
 Discussion of the Science—The Scientific Methods Applied in Firearms and
 Toolmark Examination, in 4 Modern Scientific Evidence: The Law and Science of
 Expert Testimony § 34:9 (David L. Faigman et al. eds., 2021) (discussing the general
 method of toolmark examination).

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 model.” United States v. Willock, 696 F. Supp. 2d 536, 557–58 (D. Md. 2010)

 (internal quotation marks omitted). For cartridge cases this includes caliber and the

 shape of the firing pin (which affects the firing pin’s impression on the cartridge). “If

 the class characteristics are similar, the examination proceeds to identify and

 compare individual characteristics, such as the striae that arise during firing from a

 particular gun.” PCAST Report at 104. Examiners can make an “Identification”—that

 is, conclude that two specimens were derived from the same source (such as a

 firearm)—when there is:

       Agreement of all discernible class characteristics and sufficient
       agreement of a combination of individual characteristics where the
       extent of agreement exceeds that which can occur in the comparison of
       toolmarks made by different tools and is consistent with the agreement
       demonstrated by toolmarks known to have been produced by the same
       tool.

 Ass’n of Firearm and Tool Mark Exam’rs, Glossary 94 (6th ed. 2013) (defining

 Identification) [hereinafter AFTE Glossary]. In arriving at an identification the

 examiner tries to avoid confusing individual characteristics with subclass

 characteristics—features produced during manufacture, not by design, that are

 “consistent among items fabricated by the same tool in the same approximate state of

 wear.” Id. at 121.3 On the opposite end of the spectrum, when there is “[s]ignificant

       3
          For example, “an imperfection on a rifling tool” can “impart[] similar tool
 marks on a number of barrels before being modified either through use or
 refinishing.” Ronald G. Nichols, Defending the Scientific Foundations of the
 Firearms and Tool Mark Identification Discipline: Responding to Recent Challenges,
 52 J. Forensic Sci. 586, 587 (2007). An examiner who is not attuned to this
 possibility or lacks adequate training or experience may make a misidentification of
 two bullets as having come from the same weapon, when the two weapons that fired
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 disagreement of discernible class characteristics and/or individual characteristics,” an

 examiner can determine that the specimens came from different sources—this is

 known as an “Elimination” conclusion. Id. at 94 (defining Elimination).

       In recent years the field of firearm toolmark examination has been subjected to

 closer scrutiny as part of a general program to examine the validity of feature-

 comparison forensic methods used in the courts. We discuss three efforts which were

 of special importance in the district court’s resolution of Defendant’s pretrial motion:

 (1) the 2009 NRC Report, (2) a 2014 study by the Ames Laboratory, and (3) the 2016

 PCAST Report.

       In 2005 Congress authorized the National Academy of Sciences to create a

 committee to study the needs and practices of the forensic-science community. See

 NRC Report at 1–2. The committee issued a report in 2009 in which it recommended

 that further research be conducted “to address issues of accuracy, reliability, and

 validity in the forensic science disciplines.” Id. at 22. With respect to firearm

 toolmark examination, the report found that “[s]ufficient studies have not been done

 to understand the reliability and repeatability of the methods.” Id. at 154. It also

 criticized the discipline’s “lack of a precisely defined process,” stating that “AFTE

 has adopted a theory of identification, but it does not provide a specific protocol.”

 the different bullets merely share a subclass similarity. See Adina Schwartz, A
 Systemic Challenge to the Reliability and Admissibility of Firearms and Toolmark
 Identification, 6 Colum. Sci. & Tech. L. Rev. 1, 8–10 (2005).
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 Id. at 155. The NRC Report recognized, however, that firearm toolmark evidence can

 be valuable:

        The committee agrees that class characteristics are helpful in narrowing
        the pool of tools that may have left a distinctive mark. Individual
        patterns from manufacture or from wear might, in some cases, be
        distinctive enough to suggest one particular source, but additional
        studies should be performed to make the process of individualization
        more precise and repeatable.

 Id. at 154.

        In response to the NRC Report’s recommendations, research was conducted to

 better assess the validity of firearm toolmark examination. We discuss here a study

 by the Ames Laboratory. See David P. Baldwin et al., A Study of False-Positive and

 False-Negative Error Rates in Cartridge Case Comparisons, Ames Laboratory,

 USDOE Technical Report # IS-5207 (2014) [hereinafter Ames Study]. The Ames

 Study tested 218 firearm examiners by sending each of them 15 sets of four spent

 cartridge cases. See Ames Study at 3–5, 8–10. The researchers generated the spent

 cartridge cases using 25 Ruger SR9 semiautomatic 9mm handguns.4 See id. at 5, 9–

 10. The examiners were to determine whether the fourth cartridge case in each set

 (the questioned case) came from the same firearm as the three other cartridge cases in

 that set (the known cases). See id. at 4, 10, 15–16. For each examiner the three

 cartridge cases came from a different firearm than the fourth case in 10 of the 15 sets.

 See id. at 10. The examiners thus conducted 2,180 “true different-source

        4
         While the PCAST Report approved of the Ames Study’s research design, it
 did note one forensic scientist’s criticism that “the study did not involve
 consecutively manufactured guns.” PCAST Report at 110 n.331.
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  comparisons” in total: among these, there were 1,421 correct elimination conclusions,

  735 inconclusive findings, and 22 erroneous identification conclusions. Id. at 16.

        The false-positive rate in the Ames Study, excluding inconclusive

  determinations, was 1.52%. This may overestimate the error rate for firearm toolmark

  examinations that most law-enforcement agencies and laboratories conduct. Notably,

  “[a]ll but two of the 22 false identification calls were made by five of the 218

  examiners, strongly suggesting that this error probability is not consistent across

  examiners.” Id. And “the study specifically asked participants not to use their

  laboratory or agency peer review process.” Id. at 5. Therefore, the error rate for

  comparisons that are peer-reviewed could be lower than 1.52%.

        In 2015 the President’s Council of Advisors on Science and Technology began

  investigating “whether there [were] additional steps on the scientific side, beyond

  those already taken by the Administration in the aftermath of the highly critical 2009

  [NRC Report], that could help ensure the validity of forensic evidence used in the

  Nation’s legal system.” PCAST Report at x. Like its predecessor, the PCAST

  Report—issued in 2016—said that there is a need for additional studies to verify the

  principles and methods underlying firearm toolmark examination; it found “that

  firearms analysis currently falls short of the criteria for foundational validity, because

  there is only a single appropriately designed study to measure validity and estimate

  reliability”—the Ames Study.5 Id. at 112. The PCAST Report also complained that

        5
          According to PCAST, “Foundational validity for a forensic-science method
  requires that it be shown, based on empirical studies, to be repeatable, reproducible,
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  the standard used by toolmark examiners in making an identification is ill-defined,

  asserting that the theory of identification is “circular”: “The ‘theory’ states that an

  examiner may conclude that two items have a common origin if their marks are in

  ‘sufficient agreement,’ where ‘sufficient agreement’ is defined as the examiner being

  convinced that the items are extremely unlikely to have a different origin.” Id. at 104.

         But the PCAST Report did not call for the immediate, wholesale exclusion of

  firearm toolmark evidence from the courts. Instead it took the position that

  “[w]hether firearms analysis should be deemed admissible based on current evidence

  is a decision that belongs to the courts.” Id. at 112. The PCAST Report’s assessment

  of this field stands in stark contrast to its assessment of the state of at least one other

  forensic-science method that involves feature comparison—bitemark analysis. See id.

  at 87 (“[B]itemark analysis does not meet the scientific standards for foundational

  validity, and is far from meeting such standards.”).

         With this background in mind, we now turn to Defendant’s motion to exclude

  expert testimony regarding firearm toolmark examination. His core argument was

  that “the Government cannot show that the field of ballistics identification is

  and accurate, at levels that have been measured and are appropriate to the intended
  application. . . . It is the scientific concept we mean to correspond to the legal
  requirement, in [Federal Rule of Evidence] 702(c), of ‘reliable principles and
  methods.’” PCAST Report at 4–5. PCAST recognized that “[s]ome methods that have
  not been shown to be foundationally valid may ultimately be found to be reliable,
  although significant modifications to the methods may be required to achieve this
  goal.” Id. at 14.
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  scientifically valid.” R., Vol. I at 109.6 After discussing the critiques presented in the

  PCAST and NRC Reports, he proceeded to argue that exclusion was warranted under

  Federal Rule of Evidence 702, applying the nonexclusive factors articulated in

  Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), for assessing

  whether an expert’s methodology is sufficiently reliable for the expert’s opinion to be

  admissible evidence. The Daubert factors are: “(1) whether the [methodology] can be

  tested; (2) whether it is subject to peer review and publication; (3) the known or

  potential error rate; (4) the existence and maintenance of standards [to control the

  methodology’s application]; and (5) the general acceptance in the relevant scientific

  community.” United States v. Foust, 989 F.3d 842, 845 (10th Cir. 2021) (citing

  Daubert, 509 U.S. at 593–94). Defendant argued:

               On each Daubert factor, ballistics identification evidence falls
        short. First, the very premise of firearms analysis as a field—the theory
        of uniqueness of firearms, bullets and cartridge cases—rests on an
        assumption that has not been properly tested. It comes from a time when
        bullets were hand-cut and unique, but the field simply has not reckoned
        with standardization and technological developments in production. . . .
               Second, “peer review and publication” is limited. There has only
        been one black-box study on firearms identification. See PCAST Report
        at 11, 111. This study was not published in a scientific journal and was
        not subject to peer review or publication. Id.
               Third, [Defendant] is aware of only one black-box study
        conducted with respect to error rates. See [i]d. at 11. The single study
        estimated an error rate, but a single study estimating such an error rate
        is insufficient to determine a known rate of error for the field. . . .
               Fourth, there are no uniform standards for controlling the
        technique’s operation. Rather, an individual makes a subjective

        6
           Defendant’s motion also argued that the government “has not shown that [its]
  firearm expert, Ron Jones, conducted his examination of the ballistics evidence in a
  reliable manner.” R., Vol. I at 109. That argument is not renewed on appeal as to
  Howard Kong, the expert who testified at trial.
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        determination about an identification, based on his or her own internal
        compass. There is no required number of points of agreement for
        making an identification. . . .
                ...
                Although courts have also previously allowed firearms examiners
        to testify, the awareness of the limitations of ballistics identification is
        recent and growing. It does not appear that courts have yet seriously
        considered all aspects of the field’s development, or tested its reliability
        since the PCAST report decided it was not foundationally valid from a
        scientific perspective. . . . Since firearms identification meets none of
        the Daubert criteria, this Court should exclude testimony from the
        government’s proposed ballistics identification expert.

  R., Vol. I at 118–20. Defendant also contended that if the firearms-identification

  evidence was admitted, (a) the expert should not be permitted to overstate the

  certainty of his conclusion that the cartridge cases were a match and (b) the jury

  (1) should be “made aware that the foundational validity of firearms analysis as a

  field has not been established” and (2) should be informed of the error rates

  documented in the only “appropriately designed” study. Id. at 124.

        The government filed a response to Defendant’s motion in which it identified a

  second firearm expert, Howard Kong, who is a firearm and toolmark examiner with

  the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) Forensic Science

  Laboratory in California. Kong became involved in the case after images of the two

  Blazer cartridge cases—one from each incident—were separately uploaded into the

  ATF’s National Integrated Ballistics Information Network (NIBIN), a database of

  “three dimensional digital ballistic images of spent shell casings recovered from

  crime scenes and from crime gun test-fires” that “can automatically generate a list of

  potential matches,” purportedly with a “very high level of accuracy.” Erin Aslan,

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  Crime Gun Intelligence Centers: Using Technology and Intelligence as a Lead

  Generator to Identify Trigger-Pullers and Focus Enforcement and Prevention

  Efforts, DOJ J. Fed. L. & Prac., Nov. 2018, at 49, 53. The NIBIN system identified a

  potential link between the two Blazer cartridge cases; the images were then reviewed

  by a correlation review specialist, a peer reviewer, and an ATF firearm examiner

  before a NIBIN lead was generated, advising that further investigation was

  warranted. All four spent cartridge cases were then sent to the ATF laboratory, where

  Kong—who had been advised only that there was a NIBIN lead—conducted a

  microscopic comparison and concluded that “the probability that these cartridge

  cases were fired in a different firearm is so small that it is negligible.” R., Vol. I

  at 216. A peer reviewer reached the same conclusion.

         The district court denied Defendant’s motion to exclude, without a hearing, in

  a 17-page order that applied the Daubert factors to analyze the validity of firearm

  toolmark examination as a field and considered whether Jones and Kong reliably

  applied firearm-examination methods in this case. The court observed that the use of

  firearm toolmark examination in court is far from novel and that “no federal court has

  deemed such evidence wholly inadmissible.” Hunt, 464 F. Supp. 3d at 1256. It then

  analyzed the five Daubert factors. See id. at 1256–60.

         First, the district court found that “the theory of firearm toolmark

  identification can be and has been tested.” Hunt, 464 F. Supp. 3d at 1257. It cited a

  collection of studies compiled by the AFTE and noted that Defendant had presented

  no authority to the contrary. See id. at 1256–57.

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         Second, the court found that Daubert’s peer-review factor also favored

  admission, citing the AFTE Journal (a publication for firearm toolmark research), the

  PCAST and NRC Reports, and various studies that have been conducted on firearm

  toolmark examination. See id. at 1257–58.

         Third, the court found that the low error rate favored admissibility, citing the

  1.52% false-positive rate reported in the Ames Study7 and “a Miami-Dade Study that

  reported a potential error rate of less than 1.2%.” Id. at 1258. The court observed that

  “[o]ther federal courts examining the AFTE method’s rate of error have likewise

  found it to be low” and noted that Defendant had not “introduce[d] any contradictory

  studies.” Id.

         On the other hand, the district court found that the “standards that control the

  [methodology’s application]” factor weighed against admissibility because the

         7
           In Defendant’s view the real error rate of the Ames Study was roughly 35%.
  His argument is that inconclusive determinations should be considered errors because
  “the samples were controlled to ensure that they bore sufficient markings and that
  these markings where [sic] not disturbed by environmental factors.” Aplt. Br. at 27.
  He cites a portion of the Ames Study that mentions that the fired cartridge cases were
  collected in a brass catcher and that cases that fell out of the catcher were discarded.
  See Ames Study at 11–12. But this is weak support for his proposition, considering
  that the Ames Study did not “prescreen[] the quality of samples provided to the
  participants” and actually sought to collect data on how many samples “had marks
  that were suitable for comparison.” Id. at 4. In any event, we find persuasive the
  government’s argument that the Ames Study’s false-positive rate furnishes the
  relevant error rate. That is because “a false positive identification . . . is the type of
  error that could lead to a conviction premised on faulty evidence.” United States v.
  Harris, 502 F. Supp. 3d 28, 39 (D.D.C. 2020). There is no harm to the defendant if a
  toolmark examiner makes an inconclusive finding, and Defendant presents no
  evidence to support his speculation that examiners will feel pressured to render
  conclusive opinions in the trial setting.
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  general AFTE method is “subjective in nature.” Id. at 1259 (internal quotation marks

  omitted). The district court concluded, however, that “the subjectivity of a

  methodology is not fatal under Rule 702 and Daubert.” Id. at 1260 (internal quotation

  marks omitted).

        Finally, with respect to the general-acceptance factor, the district court found

  that “the AFTE method used by the Government’s expert here[] is the field’s

  established standard” and that the lack of universal acceptance—citing the NRC and

  PCAST Reports—did not preclude admission in court. Id. at 1259–60 (internal

  quotation marks omitted).

        Despite the court’s weighing of the factors in favor of admissibility, it

  restricted how the expert’s opinion could be presented. It required that the testimony

  adhere to certain limitations set forth in guidance issued by the Department of

  Justice.8 See id. at 1261–62. The experts would need to “refrain from expressing their

        8
          The following limitations are set forth in the Department of Justice’s
  “Uniform Language for Testimony and Reports for the Forensic Firearms/Toolmarks
  Discipline – Pattern Match Examination,” R., Vol. I at 295:
         An examiner shall not assert that two toolmarks originated from the
            same source to the exclusion of all other sources. This may wrongly
            imply that a ‘source identification’ conclusion is based upon a
            statistically-derived or verified measurement or an actual comparison
            to all other toolmarks in the world, rather than an examiner’s expert
            opinion.
         An examiner shall not assert that examinations conducted in the
            forensic firearms/toolmarks discipline are infallible or have a zero
            error rate.
         An examiner shall not provide a conclusion that includes a statistic
            or numerical degree of probability except when based on relevant
            and appropriate data.
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  findings in terms of absolute certainty, and they [would] 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.” Id. at 1261. The court

  permitted the experts to testify only “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.”9 Id. at 1262.

           An examiner shall not 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.
             An examiner may cite the number of examinations conducted in the
             forensic firearms/toolmarks discipline performed in his or her career
             for the purpose of establishing, defending, or describing his or her
             qualifications or experience.
           An examiner shall not 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 a judge or applicable law.
  Id. at 297. Defendant concedes that “Kong was able to follow the letter of the
  [district court’s] order” limiting the testimony but complains that his testimony
  nonetheless “provided the false sense of certainty that the order was attempting
  to avoid.” Aplt. Br. at 33. Defense counsel did not, however, raise any
  objections during Kong’s testimony at trial.
        9
           Federal Rule of Evidence 702(d) currently requires that the proponent of
  expert testimony show that “the expert has reliably applied the principles and
  methods to the facts of the case.” The Advisory Committee on Evidence Rules has
  proposed amending Rule 702(d) to require a showing that “the expert’s opinion
  reflects a reliable application of the principles and methods to the facts of the case.”
  Committee on Rules of Practice and Procedure, Judicial Conference of the United
  States, Proposed Amendments to the Federal Rules of Appellate, Bankruptcy, Civil,
  and Criminal Procedure, and the Federal Rules of Evidence 308–09 (2021)
  (emphasis added). The committee note explains that “[f]orensic 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.” Id. at 311.
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        As relevant here, Defendant proceeded to trial on Counts 8 and 9. Kong

  testified at Defendant’s trial, but Jones did not. Kong outlined his training and

  experience, which included earning a bachelor’s degree in materials engineering,

  completing a one-year course at the ATF Firearms Examiner Academy, and receiving

  six to eight months of in-house training. Before he became an official firearms

  examiner, he was required to pass a competency test. In 2009, after having acquired

  five years of experience, he passed an examination required for certification by

  AFTE. AFTE certification lasts for five years but is subject to passing yearly

  proficiency tests. He has maintained his certification and was recertified in 2014 and

  2019. Kong testified that he had 18 years of experience in firearms examination and

  that he had handled an average of 50 cases a year. Also, he has toured the facilities of

  over a dozen firearms manufacturers.

        Consistent with his written report (which had been submitted to Defendant and

  the court in response to the pretrial Daubert motion), Kong opined that the four spent

  cartridge cases found at the January and February 2019 crime scenes were fired from

  the same gun. The class characteristics of the cartridge cases “were all similar.” R.,

  Vol. III at 467. With respect to individual characteristics, he explained that he had

  examined the striated firing-pin aperture shear marks that were created when the

  “head” of each of the four cartridge cases—that is, “[t]he base of the cartridge case

  which contains the primer,” AFTE Glossary at 32—scraped against the breech face of

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  the firearm upon discharge.10 Using a comparison microscope to look at the

  cartridges side by side, he found that the striations in the shear marks were in

  “sufficient agreement . . . to identify them as having been fired from the same gun.”

  R., Vol. III at 467. He also found that the firing-pin impressions—marks left by the

  firing pin upon striking the cartridge cases—were in “excellent agreement.” Id.

  at 468.

        In discussing the striated firing-pin aperture shear marks, Kong said that there

  were “somewhere in the neighborhood of 15 to 20 . . . consecutively matching

  stria[e].” Id. Earlier in his testimony he had mentioned a study conducted by Alfred

  Biasotti and John Murdock that examined the striated marks left on bullets fired from

  different firearms and concluded that the best agreement between two different-

  source bullets was “maybe three or four consecutive matching striations,” that is,

  lines that are “consecutive and right next to each other.” Id. at 462. According to

  Kong, the study’s authors concluded that “if you have six consecutive stria[e], then

  that would signify a match.” Id. He thus opined that this was “not a borderline case in

  terms of identification.” Id. at 468. He said that he was able to reach his conclusion

  to “a reasonable degree of certainty within the firearms examination field.” Id.

        10
           Kong described the breech face as “the backstop or the area that contacts the
  base of the cartridge case. . . . [W]hen the cartridge fires, it pushes the case back
  against this breech face and picks up marks.” R., Vol. III at 453. The firing-pin
  aperture is “[t]he hole in the breech face of a firearm through which the firing pin
  protrudes.” AFTE Glossary at 52. Aperture shear marks are “[s]triated marks caused
  by the rough edges of the firing pin aperture scraping the primer metal during
  unlocking of the breech.” Id. at 52–53.
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        Kong also testified that, based on differences in class characteristics, the

  recovered cartridge casings could not have been fired by two firearms he was asked

  to examine, firearms that belonged to two of the men who accompanied Defendant

  during the January 2019 incident. The testimony at trial indicated that Defendant was

  the only other person—of the four men who confronted Brison—who could have

  carried a gun during that incident. Defense counsel did not conduct any cross-

  examination of Kong. Defendant was convicted on all counts that went to trial and

  sentenced to 960 months in prison.

        II.    DISCUSSION

        We review for abuse of discretion the district court’s application of Daubert in

  denying Defendant’s motion to exclude the firearms-examination evidence. See

  Foust, 989 F.3d at 845. “We give the district court substantial deference, reversing

  only when its ruling was arbitrary, capricious, whimsical, or manifestly unreasonable

  or when it made a clear error of judgment or exceeded the bounds of permissible

  choice in the circumstances.” Id. (internal quotation marks omitted).

        But “we review de novo the question of whether the district court applied the

  proper standard [in admitting an expert’s testimony] and actually performed its

  gatekeeper role in the first instance.” Dodge v. Cotter Corp., 328 F.3d 1212, 1223

  (10th Cir. 2003). This is because “[w]hile the district court has discretion in the

  manner in which it conducts its Daubert analysis, there is no discretion regarding the

  actual performance of the gatekeeper function.” Goebel v. Denver & Rio Grande W.

  R.R. Co., 215 F.3d 1083, 1087 (10th Cir. 2000) (emphasis in original). Thus, our de

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  novo review is limited to whether the district court properly followed the Daubert

  framework and performed an adequate inquiry into the relevance and reliability of

  the expert testimony. See Kumho Tire Co. v. Carmichael, 526 U.S. 137, 147 (1999);

  Dodge, 328 F.3d at 1221. “For purposes of appellate review, a natural requirement of

  the gatekeeping function is the creation of a sufficiently developed record in order to

  allow a determination of whether the district court properly applied the relevant law.”

  Adamscheck v. Am. Fam. Mut. Ins. Co., 818 F.3d 576, 586 (10th Cir. 2016) (brackets

  and internal quotation marks omitted). And the trial court is required to “reply in

  some meaningful way to the Daubert concerns the objector has raised.” StorageCraft

  Tech. Co. v. Kirby, 744 F.3d 1183, 1190 (10th Cir. 2014).

                A.     The District Court’s Gatekeeping Role

          Defendant does not dispute that the district court cited “the [Daubert] factors

  and looked to them exclusively.” Aplt. Br. at 16. But he contends that the district

  court “procedurally erred in its application of Daubert” because it failed to conduct a

  diligent assessment of the available empirical evidence before making its ruling. Id.

  at 14. He faults the district court for taking “a short-cut around Daubert by relying on

  prior judicial decisions instead of conducting a meaningful review of the science.”

  Id.11

          11
           Defendant appears to argue that this critical assessment should have
  included a “probing inquiry,” Aplt. Br. at 26, into the methodologies used in the
  Miami-Dade and Ames Studies, and a thorough analysis of the peer-review procedure
  and publication practices of the ATFE Journal. But Defendant did not raise these
  specific concerns in his pretrial brief. As we have explained, the district court’s gate-
  keeping function is flexible, “requiring the court to focus its attention on the specific
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         Defendant finds some support in the beginning of the district court’s analysis:

         The use of this type of firearm toolmark identification in criminal trials is
         “hardly novel.” United States v. Taylor, 663 F. Supp. 2d 1170, 1175
         (D.N.M. 2009). “For decades ... admission of the type of firearm
         identification testimony challenged by the defendant[ ] has been semi-
         automatic ....” United States v. Monteiro, 407 F. Supp. 2d 351, 364 (D.
         Mass. 2006); see also, e.g., United States v. Hicks, 389 F.3d 514 (5th Cir.
         2004); United States v. Johnson, 875 F.3d 1265, 1281 (9th Cir. 2017).
         Indeed, no federal court has deemed such evidence wholly inadmissible.
         See United States v. Romero-Lobato, 379 F. Supp. 3d 1111, 1117 (D. Nev.
         2019).

  Hunt, 464 F. Supp. 3d at 1256. If this was the court’s only analysis, and the court had

  rested its decision solely on other courts admitting firearm toolmark identification

  evidence, it may well have failed to perform its gatekeeping duty. But the district

  court continued, stating that “because of the seriousness of the criticisms launched

  against the methodology underlying firearms identification by Defendant in this case,

  the Court will carefully assess the reliability of this methodology, using Daubert as a

  guide.” Id. at 1256. The district court then worked through the Daubert factors, while

  considering the arguments presented in Defendant’s pretrial brief. See id. at 1256–

  60. There is nothing improper in a court adopting the reasoning of a prior court. And

  the decision primarily relied upon by the district court to support its findings, United

  States v. Romero-Lobato, discussed the PCAST and NRC reports in depth. See 379 F.

  Supp. 3d 1111, 1117–18 (D. Nev. 2019), aff’d in relevant part, No. 20-10280, 2022

  WL 2387214, at *1 (9th Cir. July 1, 2022) (unpublished). Although Defendant argues

  factors implicated by the circumstances at hand.” StorageCraft, 744 F.3d at 1190.
  The district court is not required to discuss issues that are not raised by the parties.
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  that “[t]he district court effectively took an end-run around the PCAST Report by

  relying on other decisions that either could not or did not consider the report,” Aplt.

  Reply Br. at 4, he ignores the district court’s discussion of the PCAST Report’s

  critiques that were raised by Defendant in his pretrial briefing, see Hunt, 464 F.

  Supp. 3d at 1257–58. Defendant may disagree with the manner in which the district

  court fulfilled its gatekeeping responsibilities, but because the district court analyzed

  the Daubert factors and addressed Defendant’s arguments, we conclude that the

  district court’s gatekeeping role was performed.

                B.     Admissibility of the Expert’s Testimony

         Defendant argues that the district court abused its discretion in allowing Kong

  to testify regarding his firearm toolmark examination. He claims that “firearm

  toolmark examination methods are subjective, unproven, and not subject to

  meaningful review or acceptance outside the insular community of firearm toolmark

  examiners.” Aplt. Br. at 15. Although he challenges the reliability of the AFTE

  method, he does not challenge Kong’s credentials or whether he reliably applied the

  methodology to the facts of this case.

         In reviewing the district court’s ruling, we are not limited to its exposition

  supporting the ruling. Even if the exposition may be deficient in some respects, any

  shortcoming may be harmless error if the record contains the necessary support. As

  stated in StorageCraft, “If . . . it is readily apparent from the record that the expert

  testimony was admissible, it would be pointless to require a new trial at which the

  very same evidence can and will be presented again.” 744 F.3d at 1191. In particular,

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  we may evaluate the ruling in light of evidence presented at trial that was not

  presented at the Daubert hearing. See Kinser v. Gehl Co., 184 F.3d 1259, 1271 (10th

  Cir. 1998) (In reviewing the admissibility of expert testimony, “we do not think it

  necessary to confine our review to the materials accompanying the Daubert hearing

  request. Rather, we believe we may look at the entire record, including testimony

  presented at trial.”), abrogated in part on other grounds by Weisgram v. Marley Co.,

  528 U.S. 440 (2000); see also StorageCraft, 744 F.3d at 1191–92 (in response to an

  argument that the expert made an assumption unsupported by the evidence, the court

  held that any error was harmless because the assumption was supported by party’s

  deposition); cf. United States v. Harrison, 296 F.3d 994, 1003 (10th Cir. 2002) (“[T]o

  affirm the district court’s ruling, we may decide to consider all the evidence at trial,

  including evidence not presented at the hearing on the motion in limine [to admit

  evidence].”); United States v. Corral, 970 F.2d 719, 723 (10th Cir. 1992) (“In

  evaluating the correctness of the district court’s rulings, the appellate court may

  consider the entire record developed from the trial even though such evidence may

  not have been presented during the suppression hearing.”).

        Our concern is the breadth of the district court’s ruling. It can be read as

  upholding AFTE methodology in general. This would hardly be a remarkable ruling.

  Both before and after the 2016 publication of the PCAST Report, other circuits have

  affirmed decisions to admit expert testimony grounded in the AFTE method. See

  United States v. Brown, 973 F.3d 667, 702–04 (7th Cir. 2020); United States v.

  Johnson, 875 F.3d 1265, 1281 (9th Cir. 2017); United States v. Williams, 506 F.3d

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  151, 157–62 (2d Cir. 2007). But in light of the critiques expressed in the PCAST and

  NRC Reports, we think courts should be cautious, and our holding should go no

  further than necessary. “Our task is not to determine the admissibility or

  inadmissibility of [firearm toolmark examination] for all cases but merely to decide

  whether, on this record, the district judge in this case made a permissible choice in

  exercising [his] discretion to admit the expert testimony.” United States v. Baines,

  573 F.3d 979, 989 (10th Cir. 2009).

        We therefore restrict our consideration to the specific methodology described

  by expert Kong at trial. To determine that all four cartridges were fired by the same

  weapon, Kong employed the consecutive-matching-striae (CMS) method to three-

  dimensional images of the cartridges. As we explain below, the CMS method has

  impressive empirical support that would plainly permit a court to find it reliable. The

  rub in this case is that the district court’s Order expressing its ruling on the Daubert

  motion does not describe that method or the technical literature supporting it. But

  that is hardly surprising. Until Kong testified, nothing in the record would have

  informed the court about the specific identification method used by Kong.12 Although

  the technical literature referenced by the government in its Daubert brief and by the

  court in its Order says a good deal about the CMS method, there was no reason for

        12
            The government first identified Kong as an expert in its response to
  Defendant’s motion to exclude. Defendant filed no reply challenging Kong’s
  qualifications or expertise. At trial Hunt did not cross-examine Kong or raise any
  objection to his testimony. He thereby forfeited any challenge that might derive from
  the failure to disclose this methodology before trial. Nor has Hunt raised such a
  challenge on appeal.
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  the Order to focus on that method as opposed to general AFTE methods. But if the

  court had been called on at trial to opine on this specific subset of AFTE

  methodology, there can be little doubt that the court, having already declared that the

  general AFTE methodology is reliable, would have found that the CMS method, with

  its extensive empirical support, is a fortiori reliable. Hence, any error in the court’s

  not specifically addressing the CMS method is harmless. We now turn to a discussion

  of that method and how it would affect the district court’s Daubert analysis.

         In applying the CMS method, the examiner aligns the objects being compared

  and counts the number of consecutive striae where the width, morphology, and

  relative position match exactly. Kong testified that finding six or more consecutive

  striae that match is sufficient to determine that two cartridges were fired from the

  same weapon. He also said that each additional consecutive matching stria further

  reduces the likelihood that two cartridges were fired from different weapons. Thus,

  because the four cartridge cases here had 15 to 20 consecutive matching striae, it was

  “not a borderline case in terms of identification.” R., Vol. III at 468.

         Kong said that the criterion he used was based on

         a study done some time ago by Biasotti and Murdock. And what they
         did was they looked at the best agreement and bullets that were fired
         from different firearms, and the best they came up with was, like, maybe
         three or four consecutive matching striations, and that’s the absolute
         best. So what they did was they proposed that if you have six
         consecutive strias, then that would signify a match.

  Id. at 462. He further testified that if two bullets (or cartridges) fired from different

  guns had striae that satisfied the criterion for identifying the bullets as coming from

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  the same weapon, firearms examiners would learn of the discovery, yet he had never

  heard of such a discovery.

        The criterion used by Kong is supported by the research of Biasotti and

  Murdock that he mentioned in his testimony and by several studies referenced in the

  government’s pretrial Daubert brief and in the district court’s Order. Biasotti’s

  original study, first published in 1959, examined 244 bullets and analyzed 1,200

  known match comparisons and 1,080 known nonmatch comparisons. It found

  empirical support for the proposition that a significant number of consecutive

  matching striae will appear only on bullets fired from the same gun.13 See Biasotti, A

  Statistical Study of the Individual Characteristics, supra, at 35–36; Alfred Biasotti,

  John Murdock & Bruce R. Moran, Development of Objective Criteria for

  Identification, in 4 Modern Scientific Evidence: The Law and Science of Expert

  Testimony § 34:13, at 1013–18 (David L. Faigman et al. eds., 2021). Biasotti and

  Murdock continued to research consecutive matching striae in toolmarks, and in 1997

  they formulated their “conservative quantitative criteria for identification” (the

  Biasotti-Murdock criteria). Jerry Miller, An Examination of the Application of the

  Conservative Criteria for Identification of Striated Toolmarks Using Bullets Fired

  from Ten Consecutively Rifled Barrels, 33 AFTE J. 125, 126 (2001); see Biasotti,

        13
            Before this research some experts looked to the total percent of matching
  striae (regardless of whether they were consecutive) between the two bullets to
  determine a match. But Biasotti concluded from his data that the total percent of
  matching striae was an unreliable basis for identification. See Alfred Biasotti, A
  Statistical Study of the Individual Characteristics of Fired Bullets, 4 J. Forensic Sci.
  34, 37–39 (1959).
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  Murdock & Moran, Development of Objective Criteria, supra, at 1018–20. Under

  their criteria a match is found for three-dimensional striae “when at least two

  different groups of at least three consecutive matching striae appear in the same

  relative position, or one group of six consecutive matching striae are in agreement.”14

  Michael Neel & Major Wells, A Comprehensive Statistical Analysis of Striated Tool

  Mark Examinations Part 1: Comparing Known Matches and Known Non-Matches,

  39 AFTE J. 176, 177 (2007). But to apply the criteria, the toolmark examiner must

  rule out the influence of subclass characteristics.15

        14
           Biasotti and Murdock also formulated a criterion for examining two-
  dimensional toolmarks. Two-dimensional toolmarks, also sometimes called lines,
  include “[a]ny impressed or striated toolmark that lacks apparent depth.” Neel &
  Wells, A Comprehensive Statistical Analysis of Striated Tool Mark Examinations,
  supra, at 177.) Under the two-dimensional criterion, a match occurs “when at least
  two groups of at least five consecutive matching striae appear in the same relative
  position, or one group of eight consecutive matching striae are in agreement in an
  evidence toolmark compared to a test toolmark.” Id. Biasotti’s original research
  examined two-dimensional marks.
        15
          Kong’s notes from his examination of the cartridge cases, which were
  submitted to the court, discussed his elimination of subclass characteristics:
               Aperture shear marks: The aperture shapes are similar to a
        “teardrop[,]” which means there is a ramp at the 6 o’clock position. The
        aperture shear marks had excellent correspondence, and the agreement
        was sufficient for identification. Aperture shear marks were generated
        when the primer of the cartridge case rubbed on the edge of the breech
        face at the ramp. The edge is the intersecting of these two differently
        machined surfaces and will not have subclass potential. The ramp was
        produced by a rotating cutting tool to a tilted breech, therefore
        producing toolmarks that are perpendicular to the [cartridge cases’]
        movement during firing; so no potential subclass marks are from the
        ramp.
               Firing pin marks: Excellent correspondence of a series of marks
        observed on the firing pin (FP) impression. A line was visible running
        from the 6 to 12 o’clock in the center of the FP impression, and
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        The Biasotti-Murdock criteria, the basis of the CMS method, are supported in

  several ways by technical papers referenced in the government’s Daubert brief and

  the district court’s Order. One 2007 empirical study looked at “4188 striated

  toolmark comparisons from a variety of sources”16 and found no known nonmatches

  that met the Biasotti-Murdock criteria. Id. at 179, 180. In particular, the study found

  no more than four consecutive matching three-dimensional striae in a known

  nonmatch—two less than the six required under the Biasotti-Murdock criterion. The

  study pointed out that “[t]here has been over 50 years of research regarding CMS run

  counts, beginning with Biasotti’s thesis in 1955, and no documented 2D or 3D

  comparisons have been shown to contradict the original criteria set forth by Biasotti

  and Murdock.” Id. at 190.

        The Biasotti-Murdock criteria are also supported by a theoretical analysis that

  calculated the probabilities of consecutive matches of two-dimensional striae

        appeared to be a mold line from castings or metal injection molding
        (MIM) parts. Mold surfaces can have features carryover from part to
        part. However, the firing pin appeared to have a defect that produced the
        observed corresponding marks, and such a defect could be unique, but
        can have subclass potential. If the mold has a defect, then there is
        subclass.
  R., Vol. I at 272.
        16
            The sources for this study included “fired cartridge cases, fired bullets,
  sandpaper of various grit sizes (60, 22, 320) used to scratch emulsion based film,
  chisels slid across lead foil, photomicrographs of plastic replicas taken from
  consecutively rifled barrels, fired bullets from cut sections of a Thompson Contender
  barrel, and fired bullets from consecutively rifled Bar-Sto barrels.” Neel & Wells,
  A Comprehensive Statistical Analysis of Striated Tool Mark Examinations, supra,
  at 179.
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  occurring by chance. See David Howitt, et al., A Calculation of the Theoretical

  Significance of Matched Bullets, 53 J. Forensic Sci. 868 (2008). The researchers

  found a “close similarity” between Biasotti’s 1959 experimental observations and

  their calculated probabilities. Id. 872–73. Based on their calculations, the probability

  of the random creation of eight consecutive matching two-dimensional striae (the

  Biasotti-Murdock two-dimensional criterion) would be less than one in a hundred

  million.

        In addition, the Biasotti-Murdock criteria have been successfully tested in an

  automated identification system. See Wei Chu, et al., Automatic Identification of

  Bullet Signatures Based on Consecutive Catching Striae (CMS) Criteria, 231

  Forensic Sci. Int’l 137 (2013). The system minimized subjective factors by using a

  computer program objectively applying the three-dimensional Biasotti-Murdock

  criterion. It correctly identified 29 of 30 matching bullet pairs from the “unknown”

  test set and found no false positives in 12,960 known nonmatch comparisons.

        To be sure, one can find literature criticizing the CMS method. Mr. Hunt’s

  reply brief cites a 2005 article asserting that striae counting is inherently subjective

  and that “the CMS approach fails to place firearms and toolmark identification on

  adequate statistical empirical foundations.” Schwartz, A Systemic Challenge, supra,

  at 21. But even that article recognizes advantages of CMS identification as compared

  to the general AFTE methodology. Id. at 15 (“CMS differs from and is scientifically

  superior to the subjective approach because it is interpretable in a way that is

  compatible with the probabilistic nature of identity claims.”). And more importantly,

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  articles discussed above that were published after 2005 undercut Schwartz’s

  concerns. The article by Chu, et al., shows that CMS can be applied objectively; and

  the article by Howitt, et al., provides theoretical statistical support for CMS. We also

  think it significant (1) that the CMS method is not mentioned in the PCAST report,

  which questions only AFTE methods in general and (2) that the 2009 NRC Report

  suggests that its criticism of the lack of studies supporting firearms and toolmark

  identification in general may not apply to CMS: “Recent research has attempted to

  develop a statistical foundation for assessing the likelihood that more than one tool

  could have made specific marks by assessing consecutive matching striae, but this

  approach is used in a minority of cases.” NRC Report at 154 n.63.

        We now turn to an examination of the district court’s Daubert analysis as

  supplemented by specific information on the reliability of the CMS method.

  Regarding the first Daubert factor, the district court found that “the theory of firearm

  toolmark identification can be and has been tested.” Hunt, 464 F. Supp. 3d at 1257.

  Discussion of the CMS method would only have reinforced that conclusion. By

  providing quantitative criteria for identification, the CMS method is readily testable

  and has been tested. As discussed above, the CMS method has been empirically

  tested for over 60 years and no nonmatches have been found that meet the Biasotti-

  Murdock criteria. See Neel & Wells, A Comprehensive Statistical Analysis of Striated

  Tool Mark Examinations, supra, at 190; see also Biasotti, Murdock & Moran,

  Development of Objective Criteria, supra, at 1021–23 & n.26 (summarizing the

  empirical studies evaluating Biasotti-Murdock criteria and concluding that “[n]o

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  known non-matching . . . toolmarks were found . . . which exhibited agreement in

  excess of the proposed Biasotti-Murdock criteria.”).

        The district court also determined that the second Daubert factor—whether the

  technique has been subjected to peer review and publication—weighed in favor of

  admissibility. See Hunt, 464 F. Supp. 3d at 1257–58. Again, that determination finds

  particular support with respect to the CMS method. Biasotti’s original 1959 article

  was published in the Journal of Forensic Science, which is peer-reviewed. See

  Biasotti, Murdock & Moran, Development of Objective Criteria, supra, at 1013 &

  n.5. And the other studies discussed above were each published in the AFTE Journal,

  the Journal of Forensic Science, or Forensic Science International. The studies

  supporting the CMS methodology were subject to the same peer-review process as

  the articles addressed by the district court in its Order. This factor would only be

  strengthened in support of reliability.

        The third Daubert factor is whether the technique has a known or potential rate

  of error. The district court, noting the error rates from the Ames Study (which, as

  here, involved cartridge-case comparisons) and the Miami-Dade Study, weighed this

  factor in favor of admissibility. See Hunt, 464 F. Supp. 3d at 1258.17 For the Biasotti-

        17
           We add that at least one “post-PCAST Report study . . . followed the
  PCAST recommended black-box model and found that of 1512 possible
  identifications tested, firearms examiners correctly identified 1508 casings to the
  firearm from which the casing was fired.” Harris, 502 F. Supp. 3d at 38 (citing Mark
  A. Keisler et al., Isolated Pairs Research Study, 50 AFTE J. 56, 58 (2018)). Notably,
  “[n]o false positive . . . results were reported.” Keisler et al., Isolated Pairs Research
  Study, supra, at 57.
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  Murdock criteria, there is not a known error rate from empirical testing because no

  false match has been found. But the theoretical analysis discussed above suggests

  that the probability of two random bullets satisfying the Biasotti-Murdock criteria

  would be infinitesimal. Again, consideration of the CMS method would only have

  increased the support of this factor in favor of reliability.

         The district court weighed the fourth factor—whether there are standards that

  control the technique’s operation—against admissibility. See Hunt, 464 F. Supp. 3d

  at 1259. But even if the court’s assessment is correct with respect to toolmark

  examination in general, the Biasotti-Murdock criteria provide specific objective

  standards that control the application of the CMS method. See Romero-Lobato,

  379 F. Supp. 3d at 1121 (“The CMS method, standing alone, qualifies as an objective

  standard under Daubert.”). Although the determination of subclass features and

  deciding whether two striae match may involve some subjectivity, the toolmark

  examiner’s discretion is constrained: “CMS is defined as striated markings that ‘line

  up’ exactly (close doesn’t count) with one another without a break or dissimilarity in

  between them.” Biasotti, Murdock & Moran, Development of Objective Criteria,

  supra, at 1015–16 n.8.

         Finally, the district court found that the general-acceptance factor favored

  admission because the AFTE method is widely used by firearms examiners. See

  Hunt, 464 F. Supp. 3d at 1259–60; see also Brown, 973 F.3d at 704 (district court

  observed that “firearm and toolmark analysis is widely accepted beyond the judicial

  system”). Like the other factors, consideration of the CMS method would have

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  further supported this conclusion. Although the CMS method might not be “routinely

  used by firearm examiners across the country,” Romero-Lobato, 379 F. Supp. 3d

  at 1122, this may be because “many firearms examiners consider [the Biasotti-

  Murdock criteria] to be too stringent,” United States v. Taylor, 663 F. Supp. 2d 1170,

  1178 (D.N.M. 2009). This feature of the CMS method—missing some identifications

  through the application of stringent criteria that minimize the possibility of a false

  positive—enhances the reliability of CMS-derived identifications. There is no reason

  to doubt that CMS identifications are generally accepted, at least within the

  community of firearms examiners. See Foust, 989 F.3d at 846 (“Although . . .

  acceptance by unbiased experts is always better, that does not mean this factor cannot

  support admission.”); Baines, 573 F.3d at 991 (similar).18

        We conclude that even if the district court’s opinion is inadequate to support

  the AFTE methodology for firearm toolmark examination in general, any

  shortcoming was harmless because the specific CMS method relied on by Kong has

  compelling support in his testimony and the technical literature referenced by the

  district court. And Kong’s opinion in this case seems particularly resistant to

  criticism given the large number of consecutive matching striae and his expertise and

  experience in applying the methodology.

        18
          We note that one of the most critical judicial assessments of firearm
  toolmark identification—repeatedly cited by Defendant—did not consider the CMS
  method. See generally United States v. Tibbs, No. 2016 CF1 19431, 2019 WL
  4359486 (D.C. Super. Ct. Sept. 5, 2019).
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                 C.   Response to the Concurrence

        The Concurrence complains that the majority opinion improperly goes outside

  the record and violates the principle of party presentation. Both complaints are

  unwarranted.

        First, the record. The record consists of those documents (broadly construing

  the term to include electronically stored matters, such as video or audio recordings)

  filed with the court. The scientific and technical papers referenced in the majority

  opinion that the concurrence complains were not in the record were summarized on a

  website referenced in the district court’s opinion and hyperlinked in the

  government’s memorandum filed with the court for the Daubert hearing. The only

  relevance of the referenced website was the studies it collected. Under any reasonable

  notion of record, those papers were part of the district-court record.19 They would

  surely have been part of the record if they were attached as hard copies to the

  government’s brief. Is such useless printing to be required by parties in the future?

  What purpose is advanced by not considering those papers as part of the record?

        The Concurrence suggests that maybe the papers were part of the record but

  only for a limited purpose. It says that the reference to the studies by the government

  was just to establish that such studies existed, “not their quality or content.”

        19
            That was certainly the view of defense counsel at oral argument, who
  described the website articles as “evidence.” A few seconds into his argument,
  counsel noted the citation to the website in the district court’s opinion and suggested
  that the opinion did not contain a sufficient analysis of the studies themselves,
  arguing that “[t]he court wasn’t conducting a review of the evidence by merely
  looking at that website.” Oral Argument at 1:22–1:27.
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  Concurrence at 1. But surely a court’s role in performing a Daubert analysis is not

  limited to looking at titles and counting how many there are. What sort of a

  gatekeeper is that? The court must examine contested studies to protect the system

  from junk science and self-serving ipse dixits by advocates for particular theories.

  The opposing party has every right, and every incentive, to challenge the quality of

  the studies proffered by the offering party and the relevance of their content to the

  issues before the court. Here, Defendant had retained his own ballistics expert,

  although the expert was never called to testify. The fact that the opposing party made

  no such challenge hardly means that the quality and content of the studies are not part

  of the record. A great deal of the record in every case goes unchallenged. If the

  district court had in fact read some of the referenced papers to assist it in ruling on

  the Daubert motion (which is not entirely implausible since the district-court opinion

  notes that the court visited the site two weeks before filing the opinion, see

  464 F. Supp.3d at 1257), would we be required to reverse the court’s decision

  because it went “outside the record” in reaching its decision?

        Insisting on a cramped notion of what is part of the record is particularly

  inappropriate in the present context. The studies at issue do not address adjudicative

  facts peculiar to the specific case before us. They concern legislative facts that are

  applicable to a great many, and wide range of, cases; the reliability of firearm

  toolmark examination must be assessed to determine the admissibility of evidence of

  such examinations. When the resolution of a dispute turns on legislative facts, courts

  regularly relax the restrictions on judicial inquiry. For example, while appellate

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  courts can take judicial notice of adjudicative facts only in limited circumstances,

  see Fed. R. Evid. 201; Winzler v. Toyota Motor Sales U.S.A., Inc., 681 F.3d 1208,

  1212–13 (10th Cir. 2012) (Gorsuch, J.) (appellate court may take judicial notice of

  facts “at any stage of the proceeding if the facts are not subject to reasonable dispute”

  (internal quotation marks omitted)), there are no such strict limits with respect to

  legislative facts, see Fed. R. Evid. 201 advisory committee note (“‘In determining the

  content or applicability of a rule of domestic law, the judge is unrestricted in his

  investigation and conclusion. He may reject the propositions of either party or both

  parties. He may consult the sources of pertinent data to which they refer, or he may

  refuse to do so. He may make an independent search for persuasive data or rest

  content with what he has or what the parties present.’” (quoting Edmund M. Morgan,

  Judicial Notice, 57 Harv. L. Rev. 269, 260–71 (1944))); Edward K. Cheng,

  Independent Judicial Research in the Daubert Age, 56 Duke L.J. 1263, 1293 (2007)

  [hereinafter Cheng] (“If one takes the Advisory Committee’s adoption of the Morgan

  view seriously, this conclusion [that the scientific facts used for Daubert

  determinations should be treated as legislative facts] means that the Federal Rules

  free judges to do independent research in the Daubert context.”). As noted by Prof.

  Frederick Schauer in The Decline of “The Record”: A Comment on Posner, 51 Duq.

  L. Rev. 51 (2013) [hereinafter Schauer], courts sometimes rely on nothing more than

  the personal intuitions of its members (as when it selected the burden of persuasion

  for libel actions based on how it thought the press would react to different standards,

  see New York Times v. Sullivan, 376 U.S. 254, 282 (1964); Schauer at 57–58, 63),

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  and they sometimes rely on their review of sources never presented to the court (as

  with the per curiam majority in Bush v. Gore, 531 U.S. 98, 103 (2000), and Justices

  Stevens and Breyer on multiple occasions, including for the court in Kumho Tire Co.

  v. Carmichael, 526 U.S. 137, 142–43 (1999); see Schauer at 51 n.3, 56). The

  propriety of this independent research is somewhat controversial, see, e.g., Schauer at

  51–52; Cheng at 1280–84, but when the highest court in the land uses non-record

  materials to resolve legislative facts, it is hard to justify barring appellate

  consideration of materials that were referenced in the district court and were subject

  to prior examination and dispute by all the parties.

         The Concurrence also misapplies the party-presentation principal. As we

  recently explained, that principle generally restricts the court from raising issues sua

  sponte, but it does not preclude a court from resolving a presented issue in a way not

  proposed by any party. See United States v. Cortez-Nieto, 43 F.4th 1034, 1052 (10th

  Cir. 2022). For example, what if each party in a contract dispute argues that a

  provision of a contract is unambiguous but they disagree on what that unambiguous

  meaning is? It would be wholly proper for the court to decide that the provision has a

  third meaning or that the provision is ambiguous and further factual development is

  necessary.

         Here, the government argues that AFTE methodology—as a whole—is reliable

  (so admissibility should turn only on the expertise of the examiner and the

  application of the methodology), while Defendant argues that the methodology is

  never reliable enough to be used in court. In reviewing the issue, we are not limited

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  to choosing between those alternatives. We can, and do, reserve ruling on the

  reliability of the AFTE methodology in general, largely because of the prestige of the

  government-sponsored reports questioning whether the accuracy of the methodology

  has been sufficiently tested. On the other hand, there has been considerable testing,

  over an extended period of time, of the accuracy of one subset of AFTE

  methodology—the CMS methodology used in this case. We therefore can affirm the

  conviction here without going further and addressing the more general question of

  reliability of AFTE methodology.

        Given that liberty is at stake in this case, and in most cases where expert

  firearm toolmark testimony is offered, we are reluctant to go beyond what is

  necessary in this case and provide a judicial imprimatur to AFTE methodology in

  general. Although the concurrence believes that the majority opinion takes appellate

  review beyond its proper sphere, we think our approach is fully consonant with

  traditional appellate practice and, in the circumstances, not only prudent but less

  adventurous than full endorsement of the district-court ruling. We are particularly

  reluctant to adopt the ad hoc approach of the Concurrence, which would admit the

  testimony in this case while reserving judgment on admissibility in other cases,

  without providing needed guidance to the lower courts.

        Of course, appellate judges must be particularly careful in vetting scientific or

  technical research that was not debated in district court. But nothing precluded

  Defendant, who had retained his own ballistics expert, from challenging the cited

  literature. In any event, it is not uncommon for an appellate court to perform an

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  independent Daubert analysis, as when it is assessing whether a district court’s

  failure to perform the analysis was harmless error. See Smith v. Jenkins, 732 F.3d 51,

  64–68 (1st Cir. 2013); Sarkees v. E. I. Dupont De Nemours & Co., 15 F.4th 584,

  589–93 (2d Cir. 2021); UGI Sunbury LLC v. A Permanent Easement for 1.7575

  Acres, 949 F.3d 825, 833–36 (3d Cir. 2020); Sardis v. Overhead Door Corp., 10

  F.4th 268, 285–96 (4th Cir. 2021); Anderson v. Raymond Corp., 59 F.4th 279, 283–

  85 (7th Cir. 2023); United States v. Ruvalcaba-Garcia, 923 F.3d 1183, 1190–91 (9th

  Cir. 2019). This court explicitly approved that practice in StorageCraft Technology

  Corp. v. Kirby, 744 F.3d 1183, 1190–92 & n.2 (10th Cir 2014) (Gorsuch, J.).

        What the majority opinion does in this case is significantly less

  comprehensive. We have merely supplemented the district court’s analysis from the

  Daubert hearing with the new information provided at trial. As previously noted, it is

  accepted practice for appellate courts to affirm a ruling on a pretrial motion in limine

  after considering what happened at trial. See, e.g., Kinser, 184 F.3d at 1271 (In

  reviewing the admissibility of expert testimony, “we do not think it necessary to

  confine our review to the materials accompanying the Daubert hearing request.

  Rather, we believe we may look at the entire record, including testimony presented at

  trial.”). At trial, expert witness Kong reported for the first time his use of the CMS

  methodology in comparing the cartridge shells and he described the leading study

  supporting that methodology. If there were flaws in that methodology or the studies,

  Defendant could have raised challenges; but he did not even cross-examine the

  expert. The concurrence complains that neither the parties nor the district court

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  discussed or analyzed the studies relevant to the CMS technique that were described

  on the AFTE website referenced by both the government and the court. But when

  Defendant raises no challenge to those studies or the methodology, we can properly

  assume their validity. Our approach, which the concurrence disapproves, has been

  simply to conduct our own examination of the relevant studies to confirm that the

  CMS methodology is not subject to the criticisms of firearm toolmark methods in

  general which have been made by distinguished panels of forensic experts. We see

  that as our duty, not a usurpation of power.

         In short, we determine that the support the district court found for the general

  AFTE methodology is particularly strong with respect to the specific CMS

  methodology used in this case, making it unnecessary to resolve the reliability of the

  general methodology.

         We recognize that our standard of review under Daubert is abuse of discretion.

  But the issues are much too important to be resolved by a simple wave of the hand

  and deference to the decision below. Respect for the courts is significantly reduced

  when litigation is resolved on the basis of pseudoscience that is rejected by highly

  educated and intelligent citizens who begin to think that the overlap between truth

  and judicial judgment is too slim. Appellate judges have an obligation to educate

  themselves and engage in the sometimes difficult work of assessing scientific and

  technical material. At least in this case, the analysis is not particularly difficult

  because of the extensive testing of the CMS methodology.

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        III.   CONCLUSION

        We AFFIRM Defendant’s convictions.

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  United States v. Hunt, 21-6046

  MORITZ, J., concurring.

         I agree that the district court did not abuse its discretion when it deemed Howard

  Kong’s toolmark-identification methodology reliable under Daubert v. Merrell Dow

  Pharmaceuticals, Inc., 509 U.S. 579 (1993). But unlike the majority, I would reach that

  conclusion without supplementing the district court’s analysis or engaging in an

  independent review of studies and literature about consecutive matching striae (CMS).

         Initially, I can’t join the majority’s reliance on and discussion of the CMS studies

  because those studies are not part of the record in this case. Cf. United States v. Kennedy,

  225 F.3d 1187, 1191 (10th Cir. 2000) (“This court will not consider material outside the

  record before the district court.”). To be sure, citations to most of the studies discussed by

  the majority appear on a website that the government cited once in its response to the

  motion to exclude and that the district court cited once in its order. This website,

  published by the Association of Firearm and Tool Mark Examiners (AFTE), offers

  “literature citations for the more important studies that qualify as material principally

  concerned with the validity of firearm and toolmark identification,” including “[a] short

  summary follow[ing] each citation.” Testability of the Scientific Principle, The

  Association of Firearm and Tool Mark Examiners, https://afte.org/resources/swggun-

  ark/testability-of-the-scientific-principle (last visited March 23, 2023).

         But the government’s and district court’s citations merely supported the existence

  of the studies listed on the website, not their quality or content. The government cited the
Appellate Case: 21-6046      Document: 010110832100          Date Filed: 03/24/2023         Page: 44

  website to support its assertion that “[t]he AFTE theory is regularly tested both on an

  individual level, by peer review and verification, and on a larger level with numerous

  studies.” R. vol. 1, 192. Likewise, the district court cited the website to support the

  conclusion that “the theory of firearm toolmark identification can be and has been

  tested.” United States v. Hunt, 464 F. Supp. 3d 1252, 1257 (W.D. Okla. 2020). Thus,

  contrary to the majority’s characterization—that Kong’s CMS methodology is supported

  “by several studies referenced in the government’s pretrial Daubert brief and in the

  district court’s [o]rder”—neither the government nor the district court “referenced” any

  of the studies the majority relies on. Maj. Op. 27.

         Nor are the government’s and district court’s passing citations to the AFTE

  website sufficient to incorporate any or all of the listed studies—over 100 studies

  grouped into six topics—into the record for purposes of appeal. The majority cites no

  authority to support its decision to do so, and I have found none.1 Although a reviewing

  court may sometimes affirm the admission of expert testimony despite possibly flawed

  reasoning by the district court, such harmlessness must be “readily apparent from the

  record.” StorageCraft Tech. Corp. v. Kirby, 744 F.3d 1183, 1190–91 (10th Cir. 2014)

  (emphasis added); see also Kinser v. Gehl Co., 184 F.3d 1259, 1271 (10th Cir. 1999).

         1
           The majority also fails to explain whether it reviewed all the website’s listed
  studies or how it chose the handful that it relies on. Nevertheless, because I would not
  consider such studies at all, I will not substantively engage with the majority’s
  assessment of the literature.
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  Because the studies analyzed, discussed, and applied by the majority are not part of the

  record, I can’t join the majority’s decision to rely upon them.2

         Moreover, and perhaps more critically, even if these studies are part of the record,

  neither the district court nor the parties ever mentioned such studies in their briefing

  below, let alone discussed or analyzed those studies. As a result, the court best positioned

  to evaluate the CMS literature and its reliability (the district court) had no opportunity to

  consider it. See Goebel v. Denver & Rio Grande W. R.R. Co., 215 F.3d 1083, 1088–89

  (10th Cir. 2000) (“Performance of the gatekeeping function on the record [e]nsures that a

  judgment in favor of either party factors in the need for reliable and relevant scientific

  evidence. It is not an empty exercise; appellate courts are not well-suited to exercising the

  discretion reserved to district courts.”). And the same is true on appeal: We lack the

  benefit of the parties’ positions on this literature and the reliability of the CMS method.

  Thus, the majority’s reasoning—which turns heavily, if not entirely, on its “own

  examination” of CMS literature that is included amongst a variety of other toolmark-

  identification studies on an AFTE website, Maj. Op. 41—significantly departs from “the

  principle of party presentation.” United States v. Sineneng-Smith, 140 S. Ct. 1575, 1578

  (2020). This principle “restricts courts from raising new issues,” yet the majority here

  does exactly that when it affirms the district court’s admission of Kong’s expert

         2
          The majority also appears to rely on Kong’s brief mention during his trial
  testimony of “a study done some time ago by Biasotti and Murdock.” Maj. Op. 26
  (quoting R. vol. 3, 462). But this passing mention doesn’t meaningfully incorporate the
  majority’s swath of scientific literature into the appellate record. Additionally, the study
  Kong mentioned doesn’t appear to be included on the AFTE website, which lists one
  study by Biasotti and two by Murdock, but none by both individuals.
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  testimony based on a theory of CMS reliability that no party has either “raised” or

  “responded to.” United States v. Cortez-Nieto, 43 F.4th 1034, 1052 (10th Cir. 2022)

  (emphasis omitted). In so doing, the majority does far more than “supplement[] the

  district court’s analysis”; it ignores the district court’s analysis and conducts its own.

  Maj. Op. 40.

         Because of these concerns, I would follow the parties’ lead and analyze the district

  court’s actual application of the Daubert factors. Doing so, I’m not persuaded that the

  district court erred; “nothing in the controlling legal authority” requires the “extremely

  high degree of intellectual purity” that Dominic Hunt presses on appeal. United States v.

  Baines, 573 F.3d 979, 989 (10th Cir. 2009). To be sure, neither this concurrence nor the

  majority opinion should be read to endorse the rote admission of toolmark-identification

  experts. See United States v. Smith, 756 F.3d 1179, 1193 n.13 (10th Cir. 2014) (“Firearm

  toolmark analysis has recently come under attack for depending on subjective judgment,

  rarely using control weapons, and risking an observer effect.”). But I see no abuse of

  discretion in the district court’s decision in this case. See United States v. Foust, 989 F.3d

  842, 847 (10th Cir. 2021) (finding no abuse of discretion in admitting handwriting expert

  despite “criticism of handwriting expertise in both the courts and academic literature”). I

  accordingly concur.

                                                 4