Abruquah v. State

Kobina Ebo Abruquah v. State of Maryland, No. 10, September Term, 2022. Opinion by

Fader, C.J.

EVIDENCE – EXPERT EVIDENCE

Firearms identification examiner testifying as an expert witness should not have been

permitted to offer an unqualified opinion that crime scene bullets and a bullet fragment

were fired from the petitioner’s gun. The reports, studies, and testimony presented to the

circuit court demonstrate that the firearms identification methodology employed by the

examiner in this case can support reliable conclusions that patterns and markings on bullets

are consistent or inconsistent with those on bullets fired from a particular known firearm.

Those reports, studies, and testimony do not, however, demonstrate that the methodology

used can reliably support an unqualified conclusion that such bullets were fired from a

particular firearm.

Circuit Court for Prince George’s County

Case No. CT121375X

Argued: October 4, 2022

IN THE SUPREME COURT

OF MARYLAND*

No. 10

September Term, 2022

______________________________________

KOBINA EBO ABRUQUAH

v.

STATE OF MARYLAND

______________________________________

Fader, C.J.,

Watts,

Hotten,

Booth,

Biran,

Gould,

Eaves,

JJ.

______________________________________

Pursuant to the Maryland Uniform Electronic Legal Materials

Act (§§ 10-1601 et seq. of the State Government Article) this

document is authentic.

Opinion by Fader, C.J.

Hotten, Gould, and Eaves, JJ., dissent.

2023-07-14 09:00-04:00

______________________________________

Filed: June 20, 2023

Gregory Hilton, Clerk

* At the November 8, 2022 general election, the voters of Maryland ratified a constitutional

amendment changing the name of the Court of Appeals of Maryland to the Supreme Court

of Maryland. The name change took effect on December 14, 2022.

Firearms identification, a subset of toolmark identification, is “the practice of

investigating whether a bullet, cartridge case or other ammunition component or fragment

can be traced to a particular suspect weapon.” Fleming v. State, 194 Md. App. 76, 100-01

(2010). The basic idea is that (1) features unique to the interior of any particular firearm

leave unique, microscopic patterns and marks on bullets and cartridge cases that are fired

from that firearm, and so (2) by comparing patterns and marks left on bullets and cartridge

cases found at a crime scene (“unknown samples”) to marks left on bullets and cartridge

cases fired from a known firearm (“known samples”), firearms examiners can determine

whether the unknown samples were or were not fired from the known firearm.

At the trial of the petitioner, Kobina Ebo Abruquah, the Circuit Court for Prince

George’s County permitted a firearms examiner to testify, without qualification, that

bullets left at a murder scene were fired from a gun that Mr. Abruquah had acknowledged

was his. Based on reports, studies, and testimony calling into question the reliability of

firearms identification analysis, Mr. Abruquah contends that the circuit court abused its

discretion in permitting the firearms examiner’s testimony. The State, relying on different

studies and testimony, contends that the examiner’s opinion was properly admitted.

Applying the analysis required by Rochkind v. Stevenson, 471 Md. 1 (2020), we

conclude that the examiner should not have been permitted to offer an unqualified opinion

that the crime scene bullets were fired from Mr. Abruquah’s gun. The reports, studies, and

testimony presented to the circuit court demonstrate that the firearms identification

methodology employed in this case can support reliable conclusions that patterns and

markings on bullets are consistent or inconsistent with those on bullets fired from a

particular firearm. Those reports, studies, and testimony do not, however, demonstrate that

that methodology can reliably support an unqualified conclusion that such bullets were

fired from a particular firearm.

The State also contends that any error in the circuit court’s admission of the

examiner’s testimony was harmless. Because we are not convinced “beyond a reasonable

doubt, that the error in no way influenced the verdict,” Dionas v. State, 436 Md. 97, 108

(2013) (quoting Dorsey v. State, 276 Md. 638, 659 (1976)), we must reverse and remand

for a new trial.

BACKGROUND

Factual Background

On August 3, 2012, police responded to three separate calls complaining of

disturbances at the house that Mr. Abruquah shared with his roommate, Ivan Aguirre-

Herrera. On the third of these occasions, just before midnight, two officers arrived at the

house. According to the officers, Mr. Abruquah appeared “agitated,” “very aggressive,”

and uncooperative. One of the officers testified that Mr. Aguirre-Herrera appeared to be

terrified of Mr. Abruquah. Before leaving around 12:15 a.m., the officers told the men to

stay away from each other.

A neighbor of Messrs. Abruquah and Aguirre-Herrera testified that he heard

multiple gunshots sometime between 11:30 p.m. on August 3 and 12:30 a.m. on August 4.

Four days later, officers discovered Mr. Aguirre-Herrera’s body decomposing in his

bedroom. An autopsy revealed that he had been shot five times, including once in the back

2

of the head. The police recovered four bullets and two bullet fragments from the crime

scene.

During questioning, Mr. Abruquah told the police that he owned two firearms, both

hidden in the ceiling of the basement of the residence he shared with Mr. Aguirre-Herrera.

The police recovered both firearms, a Glock pistol and a Taurus .38 Special revolver.

A jailhouse informant testified that Mr. Abruquah had said that he had engaged in

“a heated argument” with Mr. Aguirre-Herrera, “snapped,” and shot him with “a 38” that

he kept in the ceiling of his basement.1

Procedural Background

Mr. Abruquah was convicted by a jury of first-degree murder and related handgun

offenses in December 2013. Abruquah v. State, No. 246, Sept. Term 2014, 2016 WL

7496174, at *1 & n.1 (Md. App. Dec. 20, 2016). In an unreported opinion, the Appellate

Court of Maryland (then named the Court of Special Appeals)2 reversed the judgment and

remanded the case for a new trial on grounds that are not relevant to the current appeal. Id.

at *9.

On remand, Mr. Abruquah filed a motion in limine to exclude firearms identification

evidence the State intended to offer through its expert witness, Scott McVeigh, a senior

firearms examiner with the Firearms Examination Unit of the Prince George’s County

The jailhouse informant testified at Mr. Abruquah’s first trial in 2013. At his

1

second trial, in 2018, the State read into the record a transcript of that prior testimony.

2

At the November 8, 2022 general election, the voters of Maryland ratified a

constitutional amendment changing the name of the Court of Special Appeals of Maryland

to the Appellate Court of Maryland. The name change took effect on December 14, 2022.

3

Police Department, Forensic Science Division. The circuit court held a four-day Frye-

Reed hearing3 during which both parties introduced evidence and elicited testimony that

we summarize below.

Following the hearing, the circuit court largely denied, but partially granted, the

motion. The court concluded that “firearm and toolmark identification is still generally

accepted and sufficiently reliable under the Frye-Reed standard” and therefore should not

be “excluded in its entirety.” Nonetheless, the court agreed with Mr. Abruquah that the

subjective nature of the matching analysis made it inappropriate for an expert to “testify to

any level of practical certainty/impossibility, ballistic certainty, or scientific certainty that

a suspect weapon matches certain bullet or casing striations.” The court thus restricted the

expert to opining whether the bullets and bullet fragment “recovered from the murder scene

fall into any of” a particular set of five classifications, one of which is “[i]dentification” of

the unknown bullet as a match to a known bullet.

At trial, Mr. McVeigh testified about the process by which he eliminated the Glock

pistol as a source of the unknown crime scene samples, created known samples from the

Taurus revolver, and compared the microscopic patterns and markings on the two sets of

samples. Over defense objection, Mr. McVeigh opined that four bullets and one bullet

3

Prior to our decision in Rochkind v. Stevenson, 471 Md. 1 (2020), courts in

Maryland determined the admissibility of expert testimony using the Frye-Reed

evidentiary standard, which “turned on the ‘general acceptance’ of such evidence ‘in the

particular field in which it belongs.’” Rochkind, 471 Md. at 4 (discussing Frye v. United

States, 293 F. 1013 (D.C. Cir. 1923) and Reed v. State, 283 Md. 374 (1978)).

4

fragment recovered from the crime scene “at some point had been fired from [the Taurus

revolver].”4

Mr. Abruquah was again convicted of first-degree murder and use of a handgun in

the commission of a crime. His first appeal from that conviction resulted in a remand to

the circuit court to consider whether it “would reach a different conclusion concerning the

admission of firearm and toolmark identification testimony” applying our then-new

decision in Rochkind v. Stevenson, 471 Md. 1, 27 (2020). In that decision, which was

issued after Mr. Abruquah’s second conviction while his appeal was pending, we

abandoned the Frye-Reed standard for admissibility of expert testimony in favor of the

standard set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993),

and its progeny. Abruquah v. State, 471 Md. 249, 250 (2020).

On remand, the circuit court held a hearing in which it once again received evidence

from both sides, which is discussed further below. The court ultimately issued an opinion

in which it reviewed each of the ten factors this Court set forth in Rochkind and concluded

that the testimony remained admissible. The court noted that although Mr. Abruquah

“ha[d] made a Herculean effort to demonstrate why the evidence should be heavily

scrutinized, questioned and potentially impeached, the State has met the burden for

admissibility of this evidence.” The court therefore sustained Mr. Abruquah’s prior

conviction.

4

Four bullets and two bullet fragments were recovered from the crime scene but

Mr. McVeigh found that one of the fragments was not suitable for comparison. As a result,

his testimony was limited to the bullets and one of the fragments.

5

Mr. Abruquah filed another timely appeal to the intermediate appellate court and,

while that appeal was pending, he filed a petition for writ of certiorari in this Court. We

granted that petition to address whether the firearms identification methodology employed

by Mr. McVeigh is sufficiently reliable to allow a firearms examiner, without any

qualification, to identify a specific firearm as the source of a questioned bullet or cartridge

case found at a crime scene. See Abruquah v. State, 479 Md. 63 (2022).

DISCUSSION

We review a circuit court’s decision to admit expert testimony for an abuse of

discretion. Rochkind, 471 Md. at 10. Under that standard, we will “not reverse simply

because . . . [we] would not have made the same ruling.” State v. Matthews, 479 Md. 278,

305 (2022) (quoting Devincentz v. State, 460 Md. 518, 550 (2018)). In connection with

the admission of expert testimony, where circuit courts are to act as gatekeepers in applying

the factors set out by this Court in Rochkind, a circuit court abuses its discretion by, for

example, admitting expert evidence where there is an analytical gap between the type of

evidence the methodology can reliably support and the evidence offered.5 See Rochkind,

471 Md. at 26-27.

5

This Court has frequently described an abuse of discretion as occurring when “no

reasonable person would take the view adopted by the circuit court” or when a decision is

“well removed from any center mark imagined by the reviewing court and beyond the

fringe of what the court deems minimally acceptable.” Matthews, 479 Md. at 305 (first

quoting Williams v. State, 457 Md. 551, 563 (2018), and next quoting Devincentz v. State,

460 Md. 518, 550 (2018)). In our view, the application of those descriptions to a trial

court’s application of a newly adopted standard, such as that adopted by this Court in

Rochkind as applicable to the admissibility of expert testimony, is somewhat unfair. In this

case, in the absence of additional caselaw from this Court implementing the newly adopted

standard, the circuit court acted deliberately and thoughtfully in approaching, analyzing,

6

Part I of our discussion sets forth the standard for the admissibility of expert

testimony in Maryland following this Court’s decision in Rochkind v. Stevenson, 471 Md.

1 (2020). In Part II, we discuss general background on the firearms identification

methodology employed by the State’s expert witness, criticisms of that methodology,

studies of the methodology, the testimony presented to the circuit court, and caselaw from

other jurisdictions. In Part III, we apply the factors set forth in Rochkind to the evidence

before the circuit court.

I. THE ADMISSIBILITY OF EXPERT TESTIMONY

The admissibility of expert testimony is governed by Rule 5-702, which provides:

Expert testimony may be admitted, in the form of an opinion or

otherwise, if the court determines that the testimony will assist the trier of

fact to understand the evidence or to determine a fact in issue. In making

that determination, the court shall determine

(1) whether the witness is qualified as an expert by knowledge, skill,

experience, training, or education,

(2) the appropriateness of the expert testimony on the particular subject,

and

(3) whether a sufficient factual basis exists to support

the expert testimony.

Trial courts analyzing the admissibility of evidence under Rule 5-702 are to consider

the following non-exhaustive list of “factors in determining whether the proffered expert

testimony is sufficiently reliable to be provided to the trier of facts,” Matthews, 479 Md. at

310:

and resolving the question before it. This Court’s majority has come to a different

conclusion concerning the outer bounds of what is acceptable expert evidence in this area.

7

(1) whether a theory or technique can be (and has been) tested;

(2) whether a theory or technique has been subjected to peer review and

publication;

(3) whether a particular scientific technique has a known or potential rate of

error;

(4) the existence and maintenance of standards and controls; . . .

(5) whether a theory or technique is generally accepted[;]

...

(6) whether experts are proposing to testify about matters growing naturally

and directly out of research they have conducted independent of the

litigation, or whether they have developed their opinions expressly for

purposes of testifying;

(7) whether the expert has unjustifiably extrapolated from an accepted

premise to an unfounded conclusion;

(8) whether the expert has adequately accounted for obvious alternative

explanations;

(9) whether the expert is being as careful as [the expert] would be in [the

expert’s] regular professional work outside [the expert’s] paid litigation

consulting; and

(10) whether the field of expertise claimed by the expert is known to reach

reliable results for the type of opinion the expert would give.

Rochkind, 471 Md. at 35-36 (first quoting Daubert, 509 U.S. at 593-94 (for factors 1-5)

and next quoting Fed. R. Evid. 702 Advisory Committee Note (cleaned up) (for factors 6-

10)).

In applying these “Daubert-Rochkind factors,” we have observed that the guidance

provided by the United States Supreme Court in Daubert and its progeny, especially

General Electric Co. v. Joiner, 522 U.S. 136 (1997), and Kumho Tire Co. v. Carmichael,

8

526 U.S. 137 (1999), “is critical to a trial court’s reliability analysis.” Rochkind, 471 Md.

at 36. In Matthews, we summarized that guidance in five principles:

• “[T]he reliability inquiry is ‘a flexible one.’” Matthews, 479 Md. at 311

(quoting Rochkind, 471 Md. at 36).

• “[T]he trial court must focus solely on principles and methodology, not on

the conclusions that they generate. However, conclusions and methodology

are not entirely distinct from one another. Thus, [a] trial court . . . must

consider the relationship between the methodology applied and conclusion

reached.” Id. (internal citations and quotation marks omitted).

• “[A] trial court need not admit opinion evidence that is connected to existing

data only by the ipse dixit of the expert; rather, [a] court may conclude that

there is simply too great an analytical gap between the data and the opinion

proffered.” Id. (internal quotation marks omitted).

• “[A]ll of the Daubert factors are relevant to determining the reliability of

expert testimony, yet no single factor is dispositive in the analysis. A trial

court may apply some, all, or none of the factors depending on the particular

expert testimony at issue.” Id. at 37.

• “Rochkind did not upend [the] trial court’s gatekeeping function. Vigorous

cross-examination, presentation of contrary evidence, and careful instruction

on the burden of proof are the traditional and appropriate means of attacking

shaky but admissible evidence.” Id. at 38 (internal quotation marks omitted).

The overarching criterion for the admission of relevant expert testimony under

Rochkind, and the goal to which each of the ten Daubert-Rochkind factors and the five

principles summarized in Matthews are all addressed, is reliability. The question for a trial

court is not whether proposed expert testimony is right or wrong, but whether it meets a

minimum threshold of reliability so that it may be presented to a jury, where it may then

be questioned, tested, and attacked through means such as cross-examination or the

submission of opposing expert testimony.

Because we evaluate a trial court’s decision to admit or exclude expert testimony

under an abuse of discretion standard, our review is necessarily limited to the information

9

that was before the trial court at the time it made the decision. A trial court can hardly

abuse its discretion in failing to consider evidence that was not before it.6

II. FIREARMS IDENTIFICATION EVIDENCE

Through multiple submissions by the parties and two evidentiary hearings over the

course of five days, the circuit court ultimately received the testimony of five witnesses

(one twice); 18 reports or articles discussing firearms identification, describing studies

testing firearms identification, or criticizing the theory or the results of the studies testing

it; and a chart identifying dozens of additional or planned studies or reports. In section A

of this Part II, we discuss firearms identification evidence generally. In sections B and C,

we review criticisms and studies of the methodology, respectively. In section D, we

summarize the testimony presented to the circuit court. Finally, in section E, we discuss

how some other courts have resolved challenges to the admissibility of firearms

identification evidence.

6

On appeal, the State cited articles presenting the results of studies that were not

presented to the circuit court and, in some cases, that were not even in existence at the time

the circuit court ruled. See, e.g., Maddisen Neuman et al., Blind Testing in Firearms:

Preliminary Results from a Blind Quality Control Program, 67 J. Forensic Scis. 964

(2022); Eric F. Law & Keith B. Morris, Evaluating Firearm Examiner Conclusion

Variability Using Cartridge Case Reproductions, 66:5 J. Forensic Scis. 1704 (2021). We

have not considered those studies in reaching our decision. If any of those studies

materially alters the analysis applicable to the reliability of the Association of Firearm and

Tool Mark Examiners theory of firearms identification, they will need to be presented in

another case.

10

A. Firearms Identification

1. The Theory Underlying Firearms Identification Generally

Firearms identification is a subset of toolmark identification. A toolmark—literally,

a mark left by a particular tool—is “generated when a hard object (tool) comes into contact

with a relatively softer object,” such as the marks that result “when the internal parts of a

firearm make contact with the brass and lead that comprise ammunition.” United States v.

Willock, 696 F. Supp. 2d 536, 555 (D. Md. 2010) (quoting Nat’l Rsch. Council, Nat’l Acad.

of Scis., Strengthening Forensic Science in the United States: A Path Forward 150 (2009)),

aff’d sub nom. United States v. Mouzone, 687 F.3d 207 (4th Cir. 2012). The marks are

then viewable using a “comparison microscope,” which a firearms examiner uses “to

compare ammunition test-fired from a recovered gun with spent ammunition from a crime

scene[.]” United States v. Monteiro, 407 F. Supp. 2d 351, 359 (D. Mass. 2006).

As a forensic technique to identify a particular firearm as the source of a particular

ammunition component, firearms identification is based on the premise that no two

firearms will make identical marks on a bullet or cartridge case. United States v. Natson,

469 F. Supp. 2d 1253, 1260 (M.D. Ga. 2007). That, the theory goes, is because the method

of manufacturing firearms results in the interior of each firearm being unique and,

therefore, making unique imprints on ammunition components fired from it. Id.

As the United States District Court for the District of Massachusetts explained:

When a firearm is manufactured, the “process of cutting, drilling, grinding,

hand-filing, and, very occasionally, hand-polishing . . . will leave individual

characteristics” on the components of the firearm. See Brian J.

Heard, Handbook of Firearms and Ballistics 127 (1997). Although modern

manufacturing methods have reduced the amount of handiwork performed

11

on an individual gun, the final step in production of most firearm parts

requires some degree of hand-filing which imparts individual characteristics

to the firearm part. See id. at 128. This process results in “randomly

produced patterns of individual stria,” or thin grooves or markings, being left

on firearm parts. Id. These parts are assembled to compose the final firearm.

When a round (a single “shot”) of ammunition is fired from a particular

firearm, the various components of the ammunition come into contact with

the firearm at very high pressures. As a result, the individual markings on

the firearm parts are transferred to the ammunition. Id. The ammunition is

composed primarily of the bullet and the cartridge case. The bullet is the

missile-like component of the ammunition that is actually projected from the

firearm, through the barrel, toward the target. . . . The cartridge case is the

part of the ammunition situated behind the bullet containing the primer and

propellant, the explosive mixture of chemicals that causes the bullet to be

projected through the barrel. Id. at 42.

Monteiro, 407 F. Supp. 2d at 359-60.

The patterns and marks left on bullets and cartridge cases are classified into three

categories. First, “class characteristics” are common to all bullets and cartridge cases fired

from “weapons of the make and model that fired the ammunition.” Willock, 696 F. Supp.

2d at 557-58. “Examples of class characteristics include the bullet’s weight and caliber;

number and width of the lands and grooves in the gun’s barrel; and the ‘twist’ (direction

of turn, i.e., clockwise or counterclockwise, of the rifling in the barrel).”7 Id. at 558.

Second, “subclass characteristics” are common to “a group of guns within a certain

make or model, such as those manufactured at a particular time and place.” Monteiro, 407

7

“Rifling” refers to “a pattern of channels that run the length of a firearm barrel,

manufactured with a helical pattern, or twist,” which has raised areas called “lands,” and

lowered areas called “grooves.” Ass’n of Firearms & Tool Mark Exam’rs, What Is Firearm

and Tool Mark Identification?, available at https://afte.org/about-us/what-is-afte/what-is-

firearm-and-tool-mark-identification (last accessed June 14, 2023), archived at

https://perma.cc/UYA4-99CS. “The number and width of lands and grooves is determined

by the manufacturer and will be the same for a large group of firearms.” Id.

12

F. Supp. 2d at 360. “An example would include imperfections ‘on a rifling tool that imparts

similar toolmarks on a number of barrels before being modified either through use or

refinishing.’” Willock, 696 F. Supp. 2d at 558 (quoting Ronald G. Nichols, Defending the

Scientific Foundations of the Firearms and Tool Mark Identification Discipline:

Responding to Recent Challenges, 52 J. Forensic Scis. 586, 587 (2007)).

Third, “individual characteristics” are those unique to an individual firearm that

therefore “distinguish [the firearm] from all others.” Willock, 696 F. Supp. 2d at 558

(quoting Monteiro, 407 F. Supp. 2d at 360). Individual characteristics include “[r]andom

imperfections produced during manufacture or caused by accidental damage.” Id.

Notably, not all individual characteristics are unique, Willock, 696 F. Supp. 2d at 558, and

individual characteristics can change over the life of a firearm as a result of, for example,

wear, polishing, or damage. As will be discussed further below, one dispute between

proponents of firearms identification and its detractors is the degree to which firearms

examiners can reliably identify the difference between subclass and individual

characteristics when performing casework.

2. The Association of Firearm and Tool Mark Examiners

Methodology

The leading methodology used by firearms examiners, and the methodology

employed in this case by Mr. McVeigh, is the Association of Firearm and Tool Mark

Examiners (“AFTE”) “Theory of Identification” (the “AFTE Theory”).8 See Committee

8

According to its website, the AFTE “is the international professional organization

for practitioners of Firearm and/or Toolmark Identification and has been dedicated to the

exchange of information, methods and best practices, and the furtherance of research since

13

for the Advancement of the Science of Firearm & Toolmark Identification, Theory of

Identification as it Relates to Toolmarks: Revised, 43 AFTE J. 287 (2011). Examiners

employing the AFTE Theory follow a two-step process. At step one, the examiner

evaluates class characteristics of the unknown and known samples. See AFTE, Summary

of the Examination Method, available at https://afte.org/resources/swggun-ark/summary-

of-the-examination-method (last accessed June 14, 2023), archived at

https://perma.cc/4D8W-UDW9. If the class characteristics do not match—i.e., if the

samples have different numbers of lands and grooves or a different twist direction—the

firearm that produced the known sample is excluded as the source of the unknown sample.

Id. If the class characteristics match, the second step involves “a comparative examination

. . . utilizing a comparison microscope.” Id. At that step, the examiner engages in “pattern

matching” “to determine: 1) if any marks present are subclass characteristics and/or

individual characteristics, and 2) the level of correspondence of any individual

characteristics.”9 Id.

its creation in 1969.” AFTE, What is AFTE?, available at https://afte.org/about-us/what-

is-afte (last accessed June 14, 2023), archived at https://perma.cc/4VKT-EZW7.

According to AFTE’s bylaws, individuals are eligible to become members if they are,

among other things, “a practicing firearm and/or toolmark examiner,” which is defined to

mean a person who “derives a substantial portion of their livelihood from the examination,

identification, and evaluation of firearms and related materials and/or toolmarks; or an

individual whose present livelihood is a direct result of the knowledge and experience

gained from the examination, identification, and evaluation of firearms and related

materials and/or toolmarks.” AFTE, AFTE Bylaws, Art. III, § 1, available at

https://afte.org/about-us/bylaws (last accessed June 14, 2023), archived at

https://perma.cc/Y2PF-XWUF.

9

An alternative to the AFTE method is the “consecutive matching striae method of

toolmark analysis” (“CMS”). Fleming, 194 Md. App. at 105. “The CMS method . . . calls

14

Based on that “pattern matching,” the examiner makes a determination in

accordance with the “AFTE Range of Conclusions,” which presents the following options:

1. “Identification” occurs when there is “[a]greement of a combination

of individual characteristics and all discernible class 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.”

2. There are three categories of “Inconclusive,” all of which require full

agreement of “all discernible class characteristics”:

(a) when there is “[s]ome agreement of individual characteristics . . . but

insufficient for an identification”;

(b) when there is neither “agreement [n]or disagreement of individual

characteristics”; and

(c) when there is “disagreement of individual characteristics, but

insufficient for an elimination.”

3. “Elimination” occurs when there is “[s]ignificant disagreement of

discernible class characteristics and/or individual characteristics.”

AFTE, Range of Conclusions, available at https://afte.org/about-us/what-is-afte/afte-

range-of-conclusions (last accessed June 14, 2023), archived at https://perma.cc/WKF5-

M6HD.

According to the AFTE, a positive “Identification” can be made when there is

“sufficient agreement” between “two or more sets of surface contour patterns” on samples.

AFTE, AFTE Theory of Identification as It Relates to Toolmarks, available at

for the examiner to consider the number of consecutive matching striae, or ‘scratches’

appearing on a projectile fragment. The theory provides that a positive ‘match’

determination can be made only when a certain, statistically established number of striae

match.” Id. Proponents of the CMS method argue that it has a “greater degree of objective

certainty” than other methods. Id. The CMS method was not used in this case.

15

https://afte.org/about-us/what-is-afte/afte-theory-of-identification (last accessed June 14,

2023), archived at https://perma.cc/E397-U8KM. “[S]ufficient agreement,” in turn:

(1) occurs when the level of agreement “exceeds the best agreement demonstrated between

toolmarks known to have been produced by different tools and is consistent with agreement

demonstrated by toolmarks known to have been produced by the same tool”; and (2) means

that “the agreement of individual characteristics is of a quantity and quality that the

likelihood another tool could have made the mark is so remote as to be considered a

practical impossibility.” Id.

The AFTE acknowledges that “[c]urrently the interpretation of

individualization/identification is subjective in nature[.]” Id. The AFTE Theory provides

no objective criteria to determine what constitutes the “best agreement demonstrated”

between toolmarks produced by different tools or what rises to the level of “quantity and

quality” of agreement demonstrating a “practical impossibility” of a different tool having

made the same mark. There are also no established standards for classifying a particular

pattern or mark as a subclass versus an individual characteristic.

B. Critiques of Firearms Identification

Firearms identification has existed as a field for more than a century.10 Throughout

most of that time, it has been accepted by law enforcement organizations and courts without

10

The first prominent use of firearms identification in the United States is attributed

to examinations made in the aftermath of the 1906 race-related incident in Brownsville,

Texas, known as the “Brownsville Affair.” There, Army personnel matched 39 out of 45

cartridge cases to two types of rifles “through the use of only magnified photographs of

firing pin impressions[.]” Kathryn E. Carso, Amending the Illinois Postconviction Statute

to Include Ballistics Testing, 56 DePaul L. Rev. 695, 700 n.43 (2007).

16

significant challenge. However, the advent of Daubert, work exposing the unreliability of

other previously accepted forensic techniques,11 and recent reports questioning the

foundations underlying firearms identification have led to greater skepticism.

Reports issued since 2008 by two blue-ribbon groups of experts outside of the

firearms and toolmark identification field have been critical of the AFTE Theory. In 2008,

the National Research Council of the National Academies of Science (the “NRC”)

published a report concerning the feasibility of developing a national database of ballistic

images to aid in criminal investigations. National Research Council, National Academy of

Sciences, Committee to Assess the Feasibility, Accuracy, and Technical Capability of a

National Ballistics Database, Ballistic Imaging 1-2 (2008), available at

https://nap.nationalacademies.org/read/12162/chapter/1 (last accessed June 14, 2023),

archived at https://perma.cc/X6NG-BNVN. In the report, the committee identified

challenges that complicate firearms identifications, and ultimately determined that the

creation of a national ballistic image database was not advisable at the time. Id. at 4-5.

11

For example, comparative bullet lead analysis was initially widely accepted

within the scientific and legal community, and admitted successfully in criminal

prosecutions nationwide, yet its validity was subsequently undermined and such evidence

is now inadmissible. See Chesson v. Montgomery Mut. Ins. Co., 434 Md. 346, 358-59

(2013) (stating that, despite the expert’s “use of th[e] technique for thirty years,”

comparative bullet lead analysis evidence was inadmissible because its “general and

underlying assumption . . . was no longer generally accepted by the relevant scientific

community”); Clemons v. State, 392 Md. 339, 364-72 (2006) (comprehensively discussing

comparative bullet lead analysis and holding that it does not satisfy Frye-Reed); Sissoko v.

State, 236 Md. App. 676, 721-27 (2018) (discussing that the “methodology

underlying [comparative bullet lead analysis], which was developed in the 1960s and

became a widely accepted forensic tool by the 1980s[,] . . . [was] undermined by many in

the relevant scientific community” and was “no longer . . . ‘valid and reliable’” (quoting

Clemons v. State, 392 Md. 339, 359 (2006))).

17

Then, in 2009, the NRC published a report in which it addressed “pressing issues”

within several forensic science disciplines, including firearms identification. National

Research Council, National Academy of Sciences, Strengthening Forensic Science in the

United States: A Path Forward 2-5 (2009) (the “2009 NRC Report”), available at

https://www.ojp.gov/pdffiles1/nij/grants/228091.pdf (last accessed June 14, 2023),

archived at https://perma.cc/RLT6-49C3.12 The NRC observed that advances in DNA

evidence had revealed flaws in other forensic science disciplines that “may have

contributed to wrongful convictions of innocent people,” id. at 4, and pointed especially to

the relative “dearth of peer-reviewed, published studies establishing the scientific bases

and validity of many forensic methods,” id. at 8.

With respect to firearms identification specifically, the NRC criticized the AFTE

Theory as lacking specificity in its protocols; producing results that are not shown to be

accurate, repeatable, and reproducible; lacking databases and imaging that could improve

the method; having deficiencies in proficiency training; and requiring examiners to offer

opinions based on their own experiences without articulated standards. Id. at 6, 63-64, 155.

In particular, the lack of knowledge “about the variabilities among individual tools and

guns” means that there is an inability of examiners “to specify how many points of

similarity are necessary for a given level of confidence in the result.” Id. at 154. Indeed,

the NRC noted, the AFTE’s guidance, which is the “best . . . available for the field of

12

The lead NRC “Committee” behind the report was the “Committee on Identifying

the Needs of the Forensic Science Community.” The committee was co-chaired by Judge

Harry T. Edwards of the United States Court of Appeals for the District of Columbia Circuit

and included members from a variety of distinguished academic and scientific programs.

18

toolmark identification, does not even consider, let alone address, questions regarding

variability, reliability, repeatability, or the number of correlations needed to achieve a given

degree of confidence.” Id. at 155. The NRC concluded that “[t]he validity of the

fundamental assumptions of uniqueness and reproducibility of firearms-related toolmarks

has not yet been fully demonstrated.” Id. at 70, 80-81, 154-55 (citation omitted).

In 2016, the President’s Council of Advisors on Science and Technology

(“PCAST”)13 issued a report identifying additional concerns about the scientific validity

of, among other forensic techniques, firearms identification. See Executive Office of the

President, President’s Council of Advisors on Science and Technology, REPORT TO THE

PRESIDENT, Forensic Science in Criminal Courts: Ensuring Scientific Validity of

Feature-Comparison Methods (2016) (the “PCAST Report”), available at

https://obamawhitehouse.archives.gov/sites/default/files/microsites/ostp/PCAST/pcast_fo

13

The PCAST Report provides the following description of PCAST’s role:

The President’s Council of Advisors on Science and Technology

(PCAST) is an advisory group of the Nation’s leading scientists and

engineers, appointed by the President to augment the science and technology

advice available to him from inside the White House and from cabinet

departments and other Federal agencies. PCAST is consulted about, and

often makes policy recommendations concerning, the full range of issues

where understandings from the domains of science, technology, and

innovation bear potentially on the policy choices before the President.

PCAST Report at iv. Members of PCAST included scholars and senior executives at

institutions and firms including Harvard University; the University of Texas at Austin,

Honeywell; Princeton University; the University of Maryland; the University of Michigan;

the University of California, Berkeley; United Technologies Corporation; Washington

University of St. Louis; Alphabet, Inc.; Northwestern University; and the University of

California, San Diego. Id. at v-vi. PCAST also consulted with “Senior Advisors”

including eight federal appellate and trial court judges, as well as law school and university

professors. Id. at viii-ix.

19

rensic_science_report_final.pdf (last accessed June 14, 2023), archived at

https://perma.cc/3QWJ-2DGR. With respect to all six forensic disciplines addressed in the

report, including firearms identification, PCAST focused on whether there had been a

demonstration of both “foundational validity” and “validity as applied.” Id. at 4-5.

Foundational validity, according to PCAST, requires that the method “be shown, based on

empirical studies, to be repeatable, reproducible, and accurate, at levels that have been

measured and are appropriate to the intended application.” Id. Validity as applied requires

“that the method has been reliably applied in practice.” Id. at 5.

With respect to firearms identification specifically, PCAST described the AFTE

Theory as a “circular” method that lacks “foundational validity” because appropriate

studies had not confirmed its accuracy, repeatability, and reproducibility. Id. at 60, 104-05.

PCAST concluded that the studies performed to that date, with one exception, were not

properly designed, had severely underestimated the false positive and false negative error

rates, or otherwise “differ[ed] in important ways from the problems faced in casework.”

Id. at 106. Among other things, PCAST noted design flaws in existing studies, including:

(1) many were not “black-box” studies,14 id. at 49; and (2) many were closed-set studies,

14

“A black box study assesses the accuracy of examiners’ conclusions without

considering how the conclusions were reached. The examiner is treated as a ‘black-box’

and the researcher measures how the output of the ‘black-box’ (examiner’s conclusion)

varies depending on the input (the test specimens presented for analysis). To test examiner

accuracy, the ‘ground truth’ regarding the type or source of the test specimens must be

known with certainty.” Organization of Scientific Area Committees for Forensic Science,

OSAC Draft Guidance on Testing the Performance of Forensic Examiners (2018),

available at https://www.nist.gov/document/drafthfcguidancedocument-may8pdf (last

accessed June 14, 2023), archived at https://perma.cc/3LH5-KURT.

20

in which comparisons are dependent upon each other and there is always a “correct” answer

within the set, id. at 106.

The sole exception to PCAST’s negative critique of study designs was a study

performed by the United States Department of Energy’s Ames Laboratory (the “Ames I

Study”), which PCAST called “the first appropriately designed black-box study of firearms

[identification].” Id. at 11. Nonetheless, PCAST observed that that study, which we

discuss below, was not published in a scientific journal, had not been subjected to peer

review, and stood alone. Id. PCAST therefore concluded that “firearms analysis currently

falls short of the criteria for foundational validity” and called for additional testing. Id. at

111-14.

C. Recent Studies of the AFTE Theory

Numerous studies of the AFTE Theory have been performed over the course of

several decades. The State contends that many of those studies are scientifically valid,

reflect extremely low false positive error rates, and therefore support the reliability of the

methodology. Mr. Abruquah argues that the studies on which the State relies are flawed

and were properly discounted by the NRC and PCAST, that even the best studies present

artificially low error rates by treating inconclusive findings as correct, and that the most

recent and authoritative study reveals “shockingly” low rates of repeatability and

reproducibility.

The State is correct that numerous studies have purported to validate the AFTE

Theory, including by identifying relatively low false positive error rates. One of the State’s

expert witnesses, Dr. James E. Hamby, is the lead author on one such study, in which 697

21

examiners inspected “over 240 test sets consisting of bullets fired through 10 consecutively

rifled RUGER P-85 pistol barrels.” James E. Hamby et al., A Worldwide Study of Bullets

Fired from 10 Consecutively Rifled 9MM Ruger Pistol Barrels—Analysis of Examiner

Error Rate, 64:2 J. Forensic Scis. 551, 551 (Mar. 2019) (the “Hamby Study”). In that

closed-set study, of 10,455 unknown bullets examined, 10,447 “were correctly identified

by participants to the provided ‘known’ bullets,” examiners could not reach a definitive

conclusion on eight bullets, and none were misidentified.15 Id. at 556. The error rate,

excluding inconclusive results, was thus 0.0%. See id.

Examples of other studies on which the State relies, all of which identify relatively

low error rates based on the study method employed, include: (1) Jamie A. Smith, Beretta

barrel fired bullet validation study, 66 J. Forensic Scis. 547 (2021) (comparison testing of

30 consecutively manufactured pistol barrels, producing a 0.55% error rate); and (2) Tasha

P. Smith et al., A Validation Study of Bullet and Cartridge Case Comparisons Using

Samples Representative of Actual Casework, 61 J. Forensic Scis. 939 (2016) (within-set

study of 31 examiners matching bullets and cartridge cases, yielding a 0.0% false-positive

rate for bullet comparisons and a 0.14% false-positive error rate for cartridge cases).

The NRC and PCAST both are critical of closed-set studies like the Hamby Study

and others that provide examiners with multiple “unknown” bullets or cartridge cases and

a corresponding number of “known” bullets or cartridge cases that the examiners are asked

15

Of the eight, the authors point out that three examiners “reported insufficient

individual characteristics for two of the test bullets and two trainees could not associate

five of the test bullets to their known counterpart bullets.” Hamby Study, at 556.

22

to match. The NRC and PCAST criticize such studies as not being representative of

casework because, among other reasons: (1) examiners are aware they are being tested;

(2) a correct match exists within the set for every sample, which the examiners also know;

and (3) the use of consecutively manufactured firearms (or barrels) in a closed-set study

has the effect of eliminating any confusion concerning whether particular patterns or marks

constitute subclass or individual characteristics. PCAST Report, at 32-33, 52-59, 107-09;

2009 NRC Report, at 154-55.

The Ames I Study, which PCAST had identified as the only one that had been

“appropriately designed” to that point, PCAST Report, at 111, was a 2014 open-set, black-

box study designed to measure error rates in the comparison of “known” and “unknown”

cartridge cases (the Ames I Study did not involve bullets). See David P. Baldwin et al., A

Study of False-Positive and False-Negative Error Rate in Cartridge Case Comparisons,

Defense Biometrics & Forensics Office, U.S. Dep’t of Energy (Apr. 2014). In the Ames I

Study, 15 sets of four cartridge cases fired from 25 new, same-model handguns using the

same type of ammunition were sent to 218 examiners. Ames I Study, at 3. Each set

included one unknown sample and three known samples fired from the same known gun,

which might or might not have been the source of the unknown sample. Id. at 4. Even

though there was a known correct answer of either an identification or an elimination for

every set, examiners were permitted to make “inconclusive” responses, which were “not

counted as an error or as a non-answer[.]” Id. at 6. Of the 1,090 comparisons where the

“known” and “unknown” cartridge cases were fired from the same source firearm, the

examiners incorrectly excluded only four cartridge cases, yielding a false-negative rate of

23

0.367%. Id. at 15. Of the 2,180 comparisons where the “known” and “unknown” cartridge

cases were fired from different firearms, the examiners incorrectly matched 22 cartridge

cases, yielding a false-positive rate of 1.01%.16 Id. at 16. However, of the non-matching

comparison sets, 735, or 33.7%, were classified as inconclusive, id., a significantly higher

percentage than in any closed-set study.

The Ames Laboratory later conducted a second open-set, black-box study that was

completed in 2020, in between the Frye-Reed and Daubert-Rochkind hearings in this case.

See Stanley J. Bajic et al., Report: Validation Study of the Accuracy, Repeatability, and

Reproducibility of Firearm Comparisons, U.S. Dep’t of Energy 1-2 (2020) (the “Ames II

Study”). The Ames II Study, which was undertaken in direct response to PCAST’s call for

further studies to demonstrate the foundational validity of firearms identification, id. at 12,

enrolled 173 examiners for a three-phase study to test for all three elements PCAST had

identified as necessary to support foundational validity: accuracy (in Phase I), repeatability

(in Phase II), and reproducibility (in Phase III). In each of three phases, each participating

examiner received 15 comparison sets of known and unknown cartridge cases and 15

comparison sets of known and unknown bullets. Id. at 23. The firearms used for the bullet

comparisons were either Beretta or Ruger handguns and the firearms used for the cartridge

case comparisons were either Beretta or Jimenez handguns. Id. Only the researchers knew

the “ground truth” for each packet; that is, which “unknown” cartridges and bullets

matched or did not match the included “known” cartridges and bullets. Id. As with the

16

The authors stressed that a significant majority of the false positive responses—

20 out of 22—came from just five of the 165 examiners. Ames I Study, at 16.

24

Ames I Study, although there was a “ground truth” correct answer for each sample set,

examiners were permitted to pick from among the full array of the AFTE Range of

Conclusions—identification, elimination, or one of the three levels of “inconclusive.” Id.

at 12-13.

The first phase of testing was designed to assess accuracy of identification, “defined

as the ability of an examiner to correctly identify a known match or eliminate a known

nonmatch.” Id. at 33. In the second phase, each examiner was given the same test set

examined in phase one, without being told it was the same, to test repeatability, “defined

as the ability of an examiner, when confronted with the exact same comparison once again,

to reach the same conclusion as when first examined.” Id. In the third phase, each

examiner was given a test set that had previously been examined by one of the other

examiners, to test reproducibility, “defined as the ability of a second examiner to evaluate

a comparison set previously viewed by a different examiner and reach the same

conclusion.” Id.

In the first phase, the results, shown in percentages, were:

25

Id. at 35. Treating inconclusive results as appropriate answers, the authors identified a

false negative rate for bullets and cartridge cases of 2.92% and 1.76%, respectively, and a

false positive rate for each of 0.7% and 0.92%, respectively. Id. Examiners selected one

of the three categories of inconclusive for 20.5% of matching bullet sets and 65.3% of non-

matching bullet sets. Id. As reflected in the following table, the results overall varied

based on the type of handgun that produced the bullet/cartridge, with examiners’ results

reflecting much greater certainty and correctness in classifying bullets and cartridge cases

fired from the Beretta handguns than from the Ruger (for bullets) and Jimenez (for

cartridge cases) handguns:17

17

“Of the 27 Beretta handguns used in the study, 23 were from a single recent

manufacturing run, and four were guns produced in separate earlier manufacturing runs.”

Ames II Study, at 56. The Ames II Study does not identify similar information for the

Ruger or Jimenez handguns.

26

Id. at 53.

Comparing the results from the second phase of testing against the results from the

first phase, intended to test repeatability, the outcomes, shown in percentages, were:

Id. at 39. Thus, an examiner classifying the same matching bullet or cartridge case set a

second time classified it in the same AFTE category 79% and 75.6% of the time,

respectively, and an examiner classifying the same non-matching bullet or cartridge case

set a second time did so 64.7% and 62.2% of the time, respectively. Id. The authors viewed

these percentages favorably, concluding that this level of “observed agreement” exceeded

the level of their “expected agreement.”18 Id. at 39-41. They did so, however, based on an

expected level of agreement reflecting the overall pattern of results from the first phase of

18

The study authors also produced alternate calculations in which they merged

either (1) all inconclusive results together or (2) positive identifications with “Inconclusive

A” results and eliminations with “Inconclusive B” results. Ames II Study, at 40. As

expected, those results produced greater agreement, although still ranging only from 71.3%

agreement to 85.5% agreement. Id. at 42.

27

testing. Id. at 39-40. In other words, the metric against which the authors gauged

repeatability was, in essence, random chance.

Comparing the results from the third phase of testing against the results of the first

phase, intended to test reproducibility, the outcomes, shown in percentages, were:

Id. at 47. Thus, an examiner classifying a matching bullet or cartridge case set previously

classified by a different examiner classified it in the same AFTE category 67.8% and 63.6%

of the time, respectively, and an examiner classifying a nonmatching bullet or cartridge

case set previously classified by a different examiner classified it in the same AFTE

category 30.9% and 40.3% of the time, respectively. Id. The authors again viewed these

percentages largely favorably. Id. at 47-49. Again, however, that conclusion was based

on a level of expected agreement that was essentially random based on the overall results

from the first phase of testing. Id. at 48-49.

The State claims support from the Ames I and Ames II Studies based on what it

calls their relatively low overall false positive rates. The State contends that those results

confirm the low false positive rates produced in every other study of firearms identification,

28

which are worthy of consideration even if they were not as robust in design as the Ames

studies. By contrast, Mr. Abruquah claims that the high rates of inconclusive responses in

both studies and the low rates of repeatability and reproducibility in the Ames II Study

further support the concerns raised by NRC and PCAST about the lack of demonstrated

foundational validity of firearms identification.

D. Witness Testimony

1. The Frye-Reed Hearing

Five witnesses testified at the two hearings conducted by the circuit court. In the

Frye-Reed hearing, Mr. Abruquah called William Tobin, a 27-year veteran of the Federal

Bureau of Investigation with 24 years’ experience at the FBI Laboratory and an expert in

forensic metallurgy. Mr. Tobin’s testimony was broadly critical of firearms identification

generally and the AFTE Theory specifically. Citing support from multiple sources, he

opined that: (1) firearms identification is “not a science,” does not follow the scientific

method, and is circular; (2) the AFTE Theory is wholly subjective and lacks any guidance

for examiners to determine the number of similarities needed to achieve an identification;

(3) in the absence of standards, examiners ignore or “rationalize away” dissimilarities in

samples; (4) examiners are incapable of distinguishing between subclass characteristics

and individual characteristics—a phenomenon referred to as “subclass carryover”—thus

undermining a fundamental premise of the AFTE Theory; (5) the studies on which the State

had relied are flawed, do not reflect actual casework, and underestimate error rates; and

(6) the AFTE Theory had not been subject to any “valid hypothesis testing” because the

studies cited as support for it “lack any indicia of scientific reliability.” Mr. Tobin opined

29

that, in the absence of a pool of samples from all other possible firearms that might have

fired the bullets at issue, the most a firearms examiner could accurately testify to in reliance

on the AFTE Theory is whether it was possible that the recovered bullets were fired from

Mr. Abruquah’s revolver.

The State presented three witnesses. It first presented Dr. James Hamby, an AFTE

firearms examiner with a Ph.D. in forensic science who had been Chief of the Firearms

Division for the United States Army Lab, authored dozens of articles and studies in the

firearms examination field, trained firearms examiners domestically and internationally,

and who, over the course of nearly 50 years in the field, managed his own forensic

laboratory and two others. Dr. Hamby testified generally about the AFTE Theory, which

he asserted had been accepted by the relevant scientific community and by courts, and

proven by numerous studies, for more than a century. Dr. Hamby agreed with PCAST that

to have foundational validity, a methodology dependent on subjective analysis must be

subjected to empirical testing by multiple groups, be repeatable and reproducible, and

provide valid estimates of the method’s accuracy. He opined that studies of firearms

identification proved that the AFTE Theory meets all those criteria and has consistently

low error rates. Dr. Hamby acknowledged that false positives can result when similarities

in subclass characteristics are mistaken for individual characteristics, but testified that

trained examiners would not make that mistake.

Dr. Hamby also discussed the controls and standards governing the work of firearms

identification examiners, including internal laboratory procedures, the AFTE training

manual, and periodic proficiency training required of every examiner. He testified that one

30

way forensic labs guard against the possibility of false positive results is by having a second

examiner review all matches to ensure the correctness of the first examiner’s decision. In

his decades of experience, Dr. Hamby was not personally aware of a second examiner ever

having reached a different conclusion than the first in actual casework, which he seemed

to view as a positive reflection on the reliability of the methodology.

The State’s second witness was Torin Suber, a forensic scientist manager with the

Maryland State Police. Like Dr. Hamby, Mr. Suber testified about the low false-positive

error rates identified in the Ames I and other studies. Mr. Suber agreed that some

examiners could potentially mistake subclass characteristics for individual characteristics,

but testified that such errors would be limited to novice examiners who “don’t actually

have that eye or knack for identification yet.”

The final witness presented at the Frye-Reed hearing was the State’s testifying

expert, Mr. McVeigh, whom the court accepted as an expert in firearms and toolmark

examinations generally, as well as “the specifics of the examination conducted in this

matter.” Mr. McVeigh testified that 100% of his work is in firearms examinations and that

firearms identification is generally accepted as reliable in the relevant scientific

community. Mr. McVeigh acknowledged the subjective standards and procedures used in

the AFTE methodology but claimed that it is “a forensic discipline with a fairly strict

methodology and a lot of rules and accreditation standards to follow.” He also relied

heavily on what he described as low error rates revealed by the Ames I Study and a separate

31

study out of Miami-Dade County.19 Although acknowledging the concern that examiners

might mistake subclass characteristics for individual characteristics, Mr. McVeigh testified

that possibility is “the number one thing[] that firearm examiners guard against.” He said

that the “current thinking in the field” is that a trained examiner can overcome that concern.

With respect to the examination he conducted in Mr. Abruquah’s case,

Mr. McVeigh testified that he received for analysis two firearms, a Glock pistol and a

Taurus revolver, along with “six fired bullet items,” one of which was unsuitable for

comparison. Based on class characteristics, he first eliminated the Glock pistol. He then

fired two rounds from the Taurus revolver and compared markings on those bullets against

the crime scene bullets using the comparative microscope. In doing so, he focused on the

“land impressions,” rather than the “groove impressions[, which] are the most likely place

where the subclass [characteristics] would occur[.]” Mr. McVeigh opined, without

qualification, that, based on his analysis, “at some point each one of those five projectiles

had been fired from the Taurus revolver.” He testified that his conclusion had been

confirmed by another examiner in his lab.

19

Mr. McVeigh referred to the Miami-Dade Study as an open-set study. Although

neither party introduced a report of the Miami-Dade Study, PCAST described it as a “partly

open” study. PCAST Report, at 109. According to PCAST, examiners were provided 15

questioned samples, 13 of which matched samples that were provided and two of which

did not. Id. Of the 330 non-matching samples that were provided, the examiners

eliminated 188 of them, reached an inconclusive determination for 138 more, and made

four false classifications. Id. The inconclusive rate for the non-matching samples was thus

41.8% with a false positive rate of 2.1%. Id. PCAST observed that even in that “partly

open” study, the inconclusive rate was “200-fold higher” and the false positive rate was

“100-fold higher” than in closed set studies. Id.

32

On cross-examination, Mr. McVeigh admitted that he did not know how Taurus

manufactured its .38 Special revolver, how many such revolvers had been consecutively

manufactured and shipped to the Prince George’s County area, or how many in the area

might show similar subclass characteristics. He also admitted that the proficiency testing

he had undergone during his career is not blind testing and is “straight forward.” Indeed,

to his knowledge, no one in his lab had ever failed a proficiency test. Mr. McVeigh asserted

that bias is not a concern in firearms examinations because the examiners are not provided

any details from the police investigation before conducting an examination.

2. The Daubert-Rochkind Hearing

At the Daubert-Rochkind hearing, each party presented only one witness to

supplement the record that had been created at the Frye-Reed hearing. The State began

with Dr. Hamby. In addition to reviewing many of the same points from his original

testimony, Dr. Hamby testified that the AFTE Theory had been tested since 1907 and peer

reviewed hundreds of times. He highlighted the low error rates produced in studies,

including those in which examiners matched bullets fired from consecutively manufactured

barrels. He was also asked about the more recent Ames II Study, but seemed to have

limited familiarity with it.

Mr. Abruquah presented testimony and an extensive affidavit from David Faigman,

Dean of the University of California Hastings College of Law, whom the court accepted as

an expert in statistical and methodological bases for scientific evidence, including research

design, scientific research, and methodology. Dean Faigman discussed several concerns

with the validity of the AFTE Theory, which were principally premised on the subjective

33

nature of the methodology, including: (1) the difference in error rates between closed- and

open-set tests; (2) potential biases in testing that might skew the results in studies, including

(a) the “Hawthorne effect,” which theorizes that participants in a test who know they are

being observed will try harder; and (b) a bias toward selecting “inconclusive” responses in

testing when examiners know it will not be counted against them, but that an incorrect

“ground truth” response will; (3) an absence of pre-testing and control groups; (4) the

“prior probability problem,” in which examiners expect a certain result and so are more

likely to find it; and (5) the lack of repeatability and reproducibility effects.

Dean Faigman agreed with PCAST that the Ames I Study “generally . . . was the

right approach to studying the subject.” He observed, however, that if inconclusives were

counted as errors, the error rate from that study would “balloon[]” to over 30%. In

discussing the Ames II Study, he similarly opined that inconclusive responses should be

counted as errors. By not doing so, he contended, the researchers had artificially reduced

their error rates and allowed test participants to boost their scores. By his calculation, when

accounting for inconclusive answers, the overall error rate of the Ames II Study was 53%

for bullet comparisons and 44% for cartridge case comparisons—essentially the same as

“flipping a coin.” Regarding the other two phases of the Ames II Study, Dean Faigman

found the rates of repeatability and reproducibility “shockingly low.”

E. The Evolving Caselaw

Until the 2008 NRC Report, most courts seem to have accepted expert testimony on

firearms identification without incident. See David H. Kaye, Firearm-Mark Evidence:

Looking Back and Looking Ahead, 68 Case Western Reserve L. Rev. 723, 723-26 (2018);

34

see also, e.g., United States v. Davis, 103 F.3d 660, 672 (8th Cir. 1996); United States v.

Natson, 469 F. Supp. 2d 1253, 1261 (M.D. Ga. 2007) (permitting an expert to testify “to a

100% degree of certainty”); United States v. Foster, 300 F. Supp. 2d 375, 376 n.1, 377

(D. Md. 2004) (stating that “numerous cases have confirmed the reliability” of firearms

and toolmark identification); United States v. Santiago, 199 F. Supp. 2d 101, 111 (S.D.N.Y.

2002); State v. Mack, 653 N.E.2d 329, 337 (Ohio 1995); Commonwealth v. Moore, 340

A.2d 447, 451 (Pa. 1975).

However, “[a]fter the NRC Report issued, some jurisdictions began to limit the

scope of a ballistics expert’s testimony.” Gardner v. United States, 140 A.3d 1172, 1183

(D.C. 2016); see also Commonwealth v. Pytou Heang, 942 N.E.2d 927, 938 (Mass. 2011)

(“Concerns about both the lack of a firm scientific basis for evaluating the reliability of

forensic ballistics evidence and the subjective nature of forensic ballistics comparisons

have prompted many courts to reexamine the admissibility of such evidence.”). Initially,

those limitations consisted primarily of precluding experts from testifying that their

opinions were offered with something approaching absolute certainty. In United States v.

Willock, for example, Judge William D. Quarles, Jr. of the United States District Court for

the District of Maryland, in adopting a report and recommendation by then-Chief

Magistrate Judge, later Judge, Paul W. Grimm of that court, permitted an examiner to

testify as to a “match” between a crime scene cartridge case and a particular firearm, but

“without any characterization as to degree of certainty.” 696 F. Supp. 2d at 572, 574; see

also United States v. Ashburn, 88 F. Supp. 3d 239, 250 (E.D.N.Y. 2015) (limiting an

expert’s conclusions to those within a “reasonable degree of certainty in the ballistics field”

35

or a “reasonable degree of ballistics certainty”); Monteiro, 407 F. Supp. 2d at 372 (stating

that the proper standard is a “reasonable degree of ballistic certainty”); United States v.

Taylor, 663 F. Supp. 2d 1170, 1180 (D.N.M. 2009) (“[The expert] will be permitted to

give . . . his expert opinion that there is a match . . . . [He] will not be permitted to testify

that his methodology allows him to reach this conclusion as a matter of scientific

certainty.”); United States v. Glynn, 578 F. Supp. 2d 567, 574-75 (S.D.N.Y. 2008)

(allowing expert testimony that it was “more likely than not” that certain bullets or casings

came from the same gun, “but nothing more”).

Following issuance of the PCAST Report, some courts have imposed yet more

stringent limitations on testimony. One example of that evolution—notable because it

involved the same judicial officer as Willock, Judge Grimm, as well as the same examiner

as here, Mr. McVeigh—is in United States v. Medley, No. PWG-17-242 (D. Md. Apr. 24,

2018), ECF No. 111. In Medley, Judge Grimm thoroughly reviewed the state of knowledge

at that time concerning firearms identification, including developments since his report and

recommendation in Willock. Judge Grimm restricted Mr. McVeigh to testifying only “that

the marks that were produced by the . . . cartridges are consistent with the marks that were

found on the” recovered firearm, and precluded him from offering any opinion that the

cartridges “were fired by the same gun” or expressing “any confidence level” in his

opinion. Id. at 119.

Some other courts, although still a minority overall, have recently imposed similar

or even more restrictive limitations. See United States v. Shipp, 422 F. Supp. 3d 762, 783

(E.D.N.Y. 2019) (limiting expert’s testimony to opining that “the recovered firearm cannot

36

be excluded as the source of the recovered bullet fragment and shell casing”); Williams v.

United States, 210 A.3d 734, 744 (D.C. 2019) (“[I]t is plainly error to allow a firearms and

toolmark examiner to unqualifiedly opine, based on pattern matching, that a specific bullet

was fired by a specific gun.”); United States v. Adams, 444 F. Supp. 3d 1248, 1256, 1261,

1267 (D. Or. 2020) (precluding expert from offering testimony of a match but permitting

testimony about “limited observational evidence”).20

III. ANALYSIS

In granting in part Mr. Abruquah’s motion in limine to exclude firearms

identification evidence, the circuit court ruled that Mr. McVeigh could not testify “to any

level of practical certainty/impossibility, ballistic certainty, or scientific certainty that a

suspect weapon matches certain bullet or casing striations.” However, the court ruled that

Mr. McVeigh could opine the bullets and fragment “recovered from the murder scene fall

into any of the AFTE Range of Conclusions[,]” i.e., identification, any of the three levels

of inconclusive, or elimination. Accordingly, at trial, after explaining how he analyzed the

samples and compared their features, Mr. McVeigh testified, over objection and separately

with respect to each of the four bullets and the bullet fragment, that each “at some point”

“had been fired” from or through “the Taurus revolver.” He testified neither that his

20

In United States v. Davis, citing Judge Grimm’s reasoning in Medley with

approval, a federal district court judge in West Virginia also precluded Mr. McVeigh and

other examiners from testifying that marks on a cartridge case indicated a “match” with a

particular firearm, while permitting the examiners to testify that marks on the cartridges

were “similar and consistent with each other.” 2019 WL 4306971, at *7, Case No. 4:18-

cr-00011 (W.D. Va. 2019).

37

opinion was offered to any particular level of certainty nor that it was subject to any

qualifications or caveats.

In his appeal, Mr. Abruquah does not challenge all of Mr. McVeigh’s testimony or

that firearms identification is sufficiently reliable to be admitted for some purposes.

Instead, he contends that the methodology is insufficiently reliable to support testimony

“identify[ing] a specific firearm as the source of a questioned bullet,” and argues that an

examiner should be limited to opining, “at most, that a firearm cannot be excluded as the

source of the questioned projectile[.]” In response, the State argues that firearms

identification evidence has been accepted by courts applying the Daubert standard as

reliable, has repeatedly been proven reliable in studies demonstrating very low false-

positive rates, and that, “[a]t best, [Mr. Abruquah] has demonstrated that there are ongoing

debates regarding how to assess the AFTE methodology[,]” not whether it is admissible.

In light of the scope of Mr. Abruquah’s challenge, our task is to assess, based on the

information presented to the circuit court, whether the AFTE Theory can reliably support

an unqualified opinion that a particular firearm is the source of one or more particular

bullets. Our analysis of the Daubert-Rochkind factors is thus tailored specifically to that

issue, not to the reliability of the methodology more generally.

Before turning to the specific Daubert-Rochkind factors, we offer two preliminary

observations. First, our analysis is not dependent on whether firearms identification is a

“science.” “Daubert’s general holding,” adopted by this Court in Rochkind, “applies not

only to testimony based on ‘scientific’ knowledge, but also to testimony based on

‘technical’ and ‘other specialized’ knowledge.” Rochkind, 471 Md. at 36 (quoting Kumho

38

Tire Co., 526 U.S. at 141). Second, it is also not dispositive that firearms identification is

a subjective endeavor. See, e.g., United States v. Romero-Lobato, 379 F. Supp. 3d 1111,

1120 (D. Nev. 2019) (“The mere fact that an expert’s opinion is derived from subjective

methodology does not render it unreliable.”); Ashburn, 88 F. Supp. 3d at 246-47 (stating

that “the subjectivity of a methodology is not fatal under [Federal] Rule 702 and Daubert”).

The absence of objective criteria is a factor that we consider in our analysis of reliability,

but it is not dispositive.

We now turn to consider each of the ten Daubert-Rochkind factors. Of course, those

factors “are neither exhaustive nor mandatory,” Matthews, 479 Md. at 314, but they provide

a helpful framework for our analysis in this case.

A. Testability

Although significant dispute surrounds many of the studies conducted on firearms

identification to date, and especially their applicability to actual casework, it is undisputed

that firearms identification can be tested. Indeed, the bottom-line recommendation of the

most significant critics of firearms identification to date, the authors of the 2009 NRC and

PCAST Reports, was to call for more and better testing, not to question whether such

testing is possible.

B. Peer Review and Publication

The second Daubert-Rochkind factor considers whether a methodology has been

submitted “to the scrutiny of the scientific community,” under the belief that doing so

“increases the likelihood that substantive flaws in methodology will be detected.” Daubert,

509 U.S. at 593. The circuit court concluded that the State satisfied its burden to show that

39

the firearms and toolmark identification methodology has been peer reviewed and

published. We think the evidence is more mixed.

The two most robust studies of firearms identification—Ames I and II—have not

been peer reviewed or published in a journal. The record does not disclose why. Some of

the articles on which the State and its witnesses rely have been published in the AFTE

Journal, a publication of the primary trade group dedicated to advancing firearms

identification. The required steps in the AFTE Journal’s peer review process involve a

review by “a member of [AFTE’s] Editorial Review Panel” for “grammatical and technical

correctness” and review by an AFTE “Assistant Editor[]” for “grammar and technical

content.” See AFTE, Peer Review Process, available at https://afte.org/afte-journal/afte-

journal-peer-review-process (last accessed June 14, 2023), archived at

https://perma.cc/822Y-C7G8. That process appears designed primarily to review articles

and studies to determine their adherence to the AFTE Theory, not to test the methodology.

Although a handful of other firearms identification studies have been published in

other forensic journals, the record is devoid of any information about the extent or quality

of peer review as concerns the validity of the methodology. Nonetheless, NRC’s and

PCAST’s critiques of some of those same studies, and of the AFTE Theory more generally,

have served many of the same purposes that might have been served by a robust peer review

process. See Shipp, 422 F. Supp. 3d at 777 (concluding that the AFTE Theory had been

adequately subjected to peer review and publication due in large part to “the scrutiny of

PCAST and the flaws it perceived in the AFTE Theory”).

40

C. Known or Potential Rate of Error

The circuit court found that the parties did not dispute “that a known or potential

rate of error has been attributed to firearms identification evidence,” and treated that as

favoring admission of Mr. McVeigh’s testimony. (Emphasis removed). Neither party

disputes that there is a potential rate of error for firearms identification or that a number of

studies have purported to identify such an error rate. However, they do dispute whether

the studies to date have identified a reliable error rate. On that issue, we glean several

relevant points from the record.

First, the reported rates of “ground truth” errors—i.e., “identification” of a non-

matching sample or “elimination” of a matching sample—from studies in the record are

relatively low.21 Error rates in most closed-set studies hover close to zero and the overall

error rates calculated in the Ames I and II Studies were in the low single digits.22 It thus

21

Most of the parties’ attention in this case is naturally focused on the “false

positive” rate. Although false positives create the greatest risk of leading directly to an

erroneous guilty verdict, an examiner’s erroneous failure to eliminate the possibility of a

match could also contribute to an erroneous guilty verdict if the correct answer—

elimination—would have led to an acquittal. To that extent, it is notable that in the first

round of testing in the Ames II Study, examiners correctly eliminated only 33.8% of non-

matching bullets and 48.5% of non-matching cartridge cases. See Ames II Study, at 35.

22

The Ames I Study identified a false negative rate of 0.367%, with a 95%

confidence interval of up to 0.94%, a false-negative-plus-inconclusive rate of 1.376%, with

a 95% confidence interval of up to 2.26%, and a false positive rate of 0.939%, with a 95%

confidence interval of up to 2.26%. Ames I Study, at 17. The Ames II Study reports its

results for bullets as having a false positive error probability of 0.656%, with a 95%

confidence interval of up to 1.42%, and a false negative error probability of 2.87%, with a

95% confidence interval of up to 4.26%. The Ames II Study results for cartridge cases

showed a false positive error probability of 0.933%, with a 95% confidence interval of up

to 1.57% and a false negative error probability of 1.87%, with a 95% confidence interval

of up to 2.99%. Ames II Study, at 77.

41

appears that, at least in studies conducted thus far, it is relatively rare for an examiner in a

study environment to identify a match between a firearm and a non-matching bullet.

Second, the low error rates from closed-set, matching studies utilizing bullets or

cartridges fired from consecutively manufactured firearms or barrels, offer strong support

for the propositions that: (1) firearms produce some unique collections of individual

patterns and markings on bullets and cartridges they fire; and (2) such collections of

individual patterns and markings can be reliably identified when subclass characteristics

are removed from the equation.23

Third, the rate of “inconclusive” responses in closed-set studies is negligible to non-

existent, see, e.g., Hamby Study, at 555-56 (finding that examiners classified eight out of

10,445 responses as inconclusive); but the rate of such responses in open-set studies is

significant, see, e.g., Ames I Study, at 16 (finding that examiners classified 33.7% of “true

different-source comparisons” as inconclusive); Ames II Study, at 35 (finding that

examiners classified more than 20% of matching bullet sets and more than 65% of non-

matching bullet sets as inconclusive), suggesting that examiners choose “inconclusive”

even when it is not a “correct” response. The State, its witnesses, and the studies on which

they rely suggest that responses of “inconclusive” are properly treated as appropriate

23

The use of bullets and cartridges from consecutively manufactured firearms or

barrels, although more difficult in the sense that the markings in total can be expected to

be more similar than those fired from non-consecutively manufactured firearms or barrels,

also makes it easier to eliminate any confusion concerning whether marks or patterns are

subclass or individual characteristics. See Tasha P. Smith et al., A Validation Study of

Bullet and Cartridge Case Comparisons Using Samples Representative of Actual

Casework, 61 J. Forensic Scis. 939 (2016) (noting that toolmarks on consecutively

manufactured firearms may be identified “when subclass influence is excused”).

42

responses because, as stated in the Ames I Study, if “the examiner is unable to locate

sufficient corresponding individual characteristics to either include or exclude an exhibit

as having been fired in a particular firearm,” then “inconclusive” is the only appropriate

response. Ames I Study, at 6. That answer would be more convincing if rates of

inconclusive findings were consistent as between closed-set and open-set studies or if the

Ames II Study had produced higher levels of consistency in the repeatability or

reproducibility portions of the study. Instead, whether an examiner chooses “inconclusive”

in a study seems to depend on something other than just the “corresponding individual

characteristics” themselves.

Fourth, if at least some inconclusives should be treated as incorrect responses, then

the rates of error in open-set studies performed to date are unreliable. Notably, if just the

“Inconclusive-A” responses—those for which the examiner thought there was almost

enough agreement to identify a match—for non-matching bullets in the Ames II Study

were counted as incorrect matches, the “false positive” rate would balloon from 0.7% to

10.13%. That is particularly noteworthy because in all the studies conducted to date, the

participating examiners knew that (1) they were being studied and (2) an inconclusive

response would not be counted as incorrect. There is no evidence in the record that

examiners in a casework environment—when processing presumably less pristine samples

than those included in studies and that were provided to them by law enforcement officers

in the context of an investigation—select inconclusive at the same rate they do in an open-

set testing environment.

43

Fifth, it is notable that the accuracy rate in the Ames II Study varied significantly

between the two different types of firearms tested. Examiners correctly classified 89.7%

of matching bullet sets fired from Beretta handguns but only 56.6% of those fired from

Ruger handguns. Ames II Study, at 53. They also correctly eliminated 38.7% of non-

matching bullet sets fired from Beretta handguns and only 21.7% of those fired from Ruger

handguns. Id. Given that variability, it is significant that the record provides scant

information about where Taurus revolvers might fall on the error rate spectrum.24

Finally, we observe that even if the studies reflecting potential error rates of up to

2.6% reflected error rates in actual casework—a proposition for which this record provides

no support—that rate must be assessed in the context of the evidence at issue. Not all

expert witness testimony is created the same. Unlike testimony that results in a

determination that the perpetrator of a crime was of a certain height range, see Matthews,

479 Md. at 285, a conclusion that a bullet found in a victim’s body was fired from the

defendant’s gun is likely to lead much more directly to a conviction. That effect is

compounded by the fact that a defendant is almost certain to lack access to the best evidence

that could potentially contradict (or, of course, confirm) such testimony, which would be

bullets fired from other firearms from the same production run.

24

During the Frye-Reed hearing, Dr. Hamby testified, using Glock as an example,

that high-quality firearms would produce bullets and cartridge cases with very consistent

patterns and markings, even across 10,000 cartridges, because the process of firing has

little effect on the firearm. He also testified that, by contrast, an examiner might not be

able to tell the difference between cartridge cases from rounds fired even consecutively

from a low-quality firearm, because each bullet “just eats up the barrel.” Asked where a

Taurus .38 revolver falls on the spectrum between a “cheap gun versus the most

expensive,” Dr. Hamby offered that “it’s mid-level.”

44

The relatively low rate of “false positive” responses in studies conducted to date is

by far the most persuasive piece of evidence in favor of admissibility of firearms

identification evidence. On balance, however, the record does not demonstrate that that

rate is reliable, especially when it comes to actual casework.

D. Existence and Maintenance of Standards and Controls

The circuit court found the evidence with respect to the existence and maintenance

of standards and controls to be “muddled” and so to weigh against admission. We mostly

agree. On the one hand, to the extent that this factor encompasses operating procedures

designed to ensure a consistency in process, see, e.g., Adams, 444 F. Supp. 3d at 1266

(discussing annual proficiency testing, second reviewer verification, technical review, and

training as relevant to the analysis of standards and quality control), the State presented

evidence of such standards and controls. That evidence includes the AFTE training

manual, laboratory standard operating procedures, and laboratory accreditation standards.

Together, those sources provide standards and controls applicable to: (1) the training and

certification of firearms examiners; (2) proficiency testing of firearms examiners; and

(3) the mechanics of how examiners treat evidence and conduct examinations. Accord

Willock, 696 F. Supp. 2d at 571-72 (finding the existence of “standards governing the

methodology of firearms-related toolmark examination”).

Notably, however, the record also contains evidence that severely undermines the

value of some of those same standards and controls. For example, one control touted by

advocates of firearms identification is a requirement that a second reviewer confirm every

identification classification. See Taylor, 663 F. Supp. 2d at 1176 (noting an expert’s

45

testimony that “industry standards require confirmation by at least one other examiner

when the first examiner reaches an identification”). Indeed, Dr. Hamby testified that he

believes error rates identified in firearms identification studies are overstated because those

studies do not permit confirmatory review by a second examiner. However, Dr. Hamby

also testified that the confirmatory review process is not blind, meaning that the second

reviewer knows the conclusion reached by the first. Even more significantly, Dr. Hamby

testified that in his decades of experience in firearms identification in multiple laboratories

in multiple states, he was not aware of a single occasion in which a second reviewer had

reached a different conclusion than the first. In light of the findings in the reproducibility

phase of the Ames II Study concerning how frequently examiners in the study environment

come to different conclusions, Dr. Hamby’s testimony strongly suggests that study results

do not, in fact, reliably represent what occurs in actual casework.

As a second example, although advocates of firearms identification tout periodic

proficiency testing by Collaborative Testing Services Inc. (“CTS”) as a method of ensuring

the quality of firearms identification, the record contains no evidence supporting efficacy

of that testing. To the contrary, the evidence suggests that examiners rarely, if ever, fail

CTS proficiency tests. Dr. Hamby confirmed that the industry’s mandate to CTS with

respect to proficiency tests “was to try to make them [as] inexpensive as possible.”

To the extent that “standards and controls” encompasses standards applicable to the

analysis itself, see, e.g., Shipp, 422 F. Supp. 3d at 779-81 (discussing the “circular and

subjective” nature of the sufficient agreement standard and the inability of examiners “to

protect against false positives” as an absence of “standards controlling the technique’s

46

operation” (quoting Daubert, 509 U.S. at 594)), firearms identification faces an even

greater challenge. As noted, “sufficient agreement,” the threshold for reaching an

“identification” classification, lacks any guiding standard other than the examiner’s own

subjective judgment. The AFTE Theory states that:

“sufficient agreement” is related to the significant duplication of random

toolmarks as evidenced by the correspondence of a pattern or combination

of patterns of surface contours.

The theory then observes that:

[a]greement is significant when the agreement in individual characteristics

exceeds the best agreement demonstrated between toolmarks known to have

been produced by different tools and is consistent with agreement

demonstrated by toolmarks known to have been produced by the same tool.

AFTE Theory (emphasis removed). The theory offers no guidance as to the quality or

quantity of shared individual characteristics—even assuming it is possible to reliably

differentiate these from subclass characteristics—that should cause an examiner to

determine that two bullets were fired from the same firearm or the quality or quantity of

different individual characteristics that should cause an examiner to reach the opposite

conclusion.25 See William A. Tobin & Peter J. Blau, Hypothesis Testing of the Critical

Underlying Premise of Discernible Uniqueness in Firearms-Toolmarks Forensic Practice,

53 Jurimetrics J. 121, 125 (2013); 2009 NRC Report, at 153-54; see also Itiel E. Dror,

Commentary, The Error in “Error Rate”: Why Error Rates Are So Needed, Yet So Elusive,

25

On cross-examination, Mr. McVeigh answered that he could not identify the

“least number of matching individual characteristics” that he had “ever used to make an

identification[,]” declining to say even whether it may have been as low as two shared

characteristics.

47

65 J. Forensic Scis. 1034, 1037 (2020) (stating that “forensic laboratories vary widely in

what decisions are verified”).

As explained in the findings of the authors of the Ames II Study, in defending the

decision not to treat inconclusive results as errors:

When confronted with a myriad of markings to be compared, a decision has

to be made about whether the variations noted rise above a threshold level

the examiner has unconsciously assigned for each examination.

Ames II Study, at 75; see also id. (“[A]ll examiners must establish for themselves a

threshold value for evaluation[.]”). A “standard” for evaluation that is dependent on each

individual examiner “unconsciously assign[ing]” a threshold level “for each examination”

may not undermine the reliability of the methodology to support generalized testimony

about the consistency of patterns and marks on ammunition fired from a particular firearm

and crime scene bullets. It does not, however, support the reliability of the methodology

to identify, without qualification, a particular crime scene bullet as having been fired from

a particular firearm.

On this issue, we find the results of phases two and three of the Ames II Study

particularly enlightening. The PCAST Report identified accuracy, repeatability, and

reproducibility as the key components of the foundational validity of any forensic

technique. PCAST Report, at 5. Dr. Hamby testified at the Frye-Reed hearing that he

agreed with that as a general proposition. The Ames II Study, which was not available at

the time of the Frye-Reed hearing, was designed specifically to test the repeatability and

reproducibility of the AFTE Theory methodology. For purposes of reviewing the

48

reliability of firearms identification to support the admissibility of expert testimony of a

“match,” the level of inconsistency identified through that study is troublesome.

Notably, at the Frye-Reed hearing, Mr. McVeigh rejected the notion that a firearms

examiner looking at a bullet multiple times might come to different conclusions, stating

that he believed that firearms identification’s “repeatability is not in question.” By the time

of the Daubert hearing, however, the Ames II Study had been released, with data revealing

that an examiner reviewing the same bullet set a second time classified it in the same AFTE

category only 79% of time for matching sets and 65% of the time for non-matching sets.

Ames II Study, at 39. In light of the black-box nature of the study, there is no explanation

of this lack of consistency or of the lack of reproducibility shown in the same study.26

Nonetheless, it highlights both (1) the absence of any standards or controls to guide the

analysis of examiners and (2) the importance of testing unverified (though undoubtedly

genuinely held) claims about reliability.

The lack of standards and controls is perhaps most acute in discerning whether a

particular characteristic is a subclass or an individual characteristic. As noted, subclass

characteristics are those shared by a group of firearms made using the same tools, such as

those made in the same production run at a facility. Individual characteristics are those

26

As noted above, the Ames II Study also found that an examiner reviewing a bullet

set previously classified by a different examiner classified it in the same AFTE category

68% of the time for matching sets and 31% of the time for non-matching sets. Ames II

Study, at 47. Even when the authors of the Ames II Study paired Identifications with

Inconclusive-A responses and Eliminations with Inconclusive-C responses, second

examiners still reached the same results as the first examiners looking at the same set of

matching bullet sets only 77.4% of the time, and did so when looking at the same set of

non-matching bullet sets only 49.0% of the time. Ames II Study, at 49.

49

specific to a particular firearm. Both can result from aspects of the manufacturing process;

individual characteristics can also result from later events, such as ordinary wear and

cleaning and polishing. Currently, there are no published standards or controls to guide

examiners in identifying whether any particular pattern or mark is a subclass or an

individual characteristic. Mr. McVeigh testified that examiners attempt to “guard against”

this “subclass carryover,” and that it is possible for a “trained examiner” to do so.27

However, neither he nor any other witness identified any industry standards or controls

addressing that topic.

On balance, consideration of the existence and maintenance of standards and

controls weighs against admission of testimony of a “match” between a particular firearm

and a particular crime scene bullet. Accord Shipp, 422 F. Supp. 3d at 782 (“[T]he court

finds that the subjective and circular nature of AFTE Theory weighs against finding that a

firearms examiner can reliably identify when two bullets or shell casings were fired from

the same gun.”).

27

Mr. Abruquah relies on a 2007 study published in the AFTE Journal that was

designed to test the possibility that cartridge cases fired from two pistols that had been

shipped to the same retailer on the same date would show similarities in subclass

characteristics. See Gene C. Rivera, Subclass Characteristics in Smith & Wesson SW40VE

Sigma Pistols, 39 AFTE J. 247 (2007) (the “Rivera Study”). The Rivera Study found

“alarming similarities” among the marks from the two different pistols, which, the author

concluded, “should raise further concern for the firearm and tool mark examiner who may

rely only on one particular type of mark for identification purposes.” Id. at 250. The Rivera

Study suggested that the AFTE Theory’s “currently accepted standard for an identification”

may need to be reconsidered as a result of very “significant” agreement between the two

different pistols. Id. The AFTE seems to have responded by clarifying in the statement of

its theory that an examiner’s decision should be based on individual characteristics, but it

has not provided standards for distinguishing those from subclass characteristics.

50

E. General Acceptance

Whether the AFTE Theory of firearms identification is generally accepted by the

relevant community is largely dependent on what the relevant community is. Based on

materials included in the record, as well as caselaw, the community of firearms

identification examiners appears to be overwhelmingly accepting of the AFTE Theory.

See, e.g., Romero-Lobato, 379 F. Supp. 3d at 1122 (stating that “[t]he AFTE method

certainly satisfies th[e general acceptance] element”); United States v. Otero, 849 F. Supp.

2d 425, 435 (D.N.J. 2012) (stating that the AFTE Theory is “widely accepted in the forensic

community and, specifically, in the community of firearm and toolmark examiners”);

Willock, 696 F. Supp. 2d at 571 (“[D]espite its inherent subjectivity, the AFTE

theory . . . has been generally accepted within the field of toolmark examiners[.]”);

Monteiro, 407 F. Supp. 2d at 372 (“[T]he community of toolmark examiners seems

virtually united in their acceptance of the current technique.”).

On the other hand, groups of eminent scientists and other academics have been

critical of the absence of studies demonstrating the validity of firearms identification

generally and the AFTE Theory specifically. See, e.g., 2009 NRC Report, at 155; PCAST

Report, at 111. Indeed, the record does not divulge evidence of general acceptance of the

methodology by any group outside of firearms identification examiners and law

enforcement.

We conclude that the relevant community for the purpose of determining general

acceptance consists of both firearms examiners and the broader scientific community that

has weighed in on the reliability of the methodology. The widespread acceptance of the

51

methodology among those who have vast experience with it, study it, and devote their

careers to it is of great significance. However, we would be remiss were we to rely

exclusively on a community that, by definition, is dependent for its livelihood on the

continued viability of a methodology to sustain it, while ignoring the relevant and

persuasive input of a different, well-qualified, and disinterested segment of professionals.28

We consider this factor to be neutral.

F. Whether Opinions Emerged Independently or Were Developed

for Litigation

The circuit court found that Mr. McVeigh’s testimony grew naturally out of research

independent of the litigation because “the ultimate purpose of th[e firearms and toolmark]

evidence is investigation [into the victim’s death], not litigation.” We disagree.

“Historically, forensic science has been used primarily in two phases of the criminal-justice

process: (1) investigation, which seeks to identify the likely perpetrator of a crime, and

(2) prosecution, which seeks to prove the guilt of a defendant beyond a reasonable

doubt.”29 See PCAST Report, at 4. The use of firearms identification in a criminal

prosecution is not independent of its investigative use. Nonetheless, the purpose of this

factor is to determine whether there is reason for skepticism that the opinion reached might

28

In his dissent, Justice Gould takes Mr. Abruquah to task for not retaining his own

firearms examiner to provide a different analysis of the bullets at issue. Dissenting Op. of

Gould, J. at 42. In doing so, Justice Gould assumes that there are firearms examiners whose

services were readily available to Mr. Abruquah, i.e., who are willing and able to take on

work for criminal defendants in such cases. The record contains no support for that

proposition.

29

Here, for example, it appears that Mr. Abruquah was already identified as the

likely perpetrator of the murder before Mr. McVeigh began his analysis of the Taurus

revolver and the crime scene bullets.

52

be tailored to the preferred result for the litigation, rather than the expert’s considered,

independent conclusion. Here, the circuit court lauded Mr. McVeigh’s integrity and

forthrightness, and we have no reason to second-guess that view.30 Crediting the court’s

findings about Mr. McVeigh’s testimony, we are confident that the court would not weigh

this factor against admissibility and so we will not either.

G. Unjustified Extrapolation from Accepted Premise

Citing Mr. Abruquah’s “voluminous data indicating that firearms identification

evidence is unjustifiably extrapolated from the toolmarks” and the State’s “credible and

persuasive evidence that all extrapolations are justifiably calculated and well-reasoned[,]”

the circuit court found “this factor to be in equipoise” and so to weigh against admission.

In Rochkind, we explained that this factor invokes the concept of an analytical gap, as

“[t]rained experts commonly extrapolate from existing data[,]” but a circuit court is not

required “to admit opinion evidence that is connected to existing data only by the ipse dixit

of the expert.” 471 Md. at 36 (quoting Joiner, 522 U.S. at 146). “An ‘analytical gap’

typically occurs as a result of ‘the failure by the expert witness to bridge the gap between

[the expert’s] opinion and the empirical foundation on which the opinion was derived.’”

Matthews, 479 Md. at 317 (quoting Savage v. State, 455 Md. 138, 163 (2017)).

30

We observe that another seasoned trial judge, even while limiting Mr. McVeigh’s

testimony more than we do here, was equally profuse in his laudatory comments about

Mr. McVeigh’s integrity. See United States v. Medley, No. PWG-17-242 (D. Md. April

24, 2019), ECF No. 111, at 14 (“Mr. McVeigh, who was, for an expert witness,

. . . remarkably forthcoming in his testimony and credible.”); id. at 53-54 (“I’ve seldom

seen an expert who is as sincere and straightforward and no baloney and genuine in what

he did as Mr. McVeigh.”). Nothing about our opinion or our conclusion in this case should

be understood as contradicting that sentiment.

53

Although we do not preclude the possibility that the gap may be closed in the future,

for the reasons already discussed, this case presents just such an analytical gap. That gap

should have foreclosed Mr. McVeigh’s unqualified testimony that the crime scene bullets

and bullet fragment were fired from Mr. Abruquah’s Taurus revolver. Although the court

precluded Mr. McVeigh from testifying to his opinions to a “certainty,” an unqualified

statement that the bullets were fired from Mr. Abruquah’s revolver is still more definitive

than can be supported by the record. To be sure, the AFTE Theory is intended to allow

firearms examiners to reach conclusions linking particular firearms to particular unknown

bullets. Mr. McVeigh’s testimony was thus not an unjustified departure from the

methodology employed by those practicing in his field. We conclude, however, for reasons

discussed above, that although the studies and other information in the record support the

use of the AFTE Theory to reliably identify whether patterns and lines on bullets of

unknown origin are consistent with those known to have been fired from a particular

firearm, they do not support the use of that methodology to reliably opine without

qualification that the bullets of unknown origin were fired from the particular firearm.

H. Accounting for Obvious Alternative Explanations

The court found this factor “definitively weighs in favor of admission” because

Mr. McVeigh and Dr. Hamby “clearly and concisely addressed how alternative

interpretations of toolmarks are generally accounted for in the field of firearms

identification,” and Mr. Abruquah’s “counters in this area were ineffective.” We disagree.

For reasons already addressed, without the ability to examine other bullets fired from other

firearms in the same production run as the firearm under examination, the record simply

54

does not support that firearms identification can reliably eliminate all alternative sources

so as to permit unqualified testimony of a match between a particular firearm and a

particular crime scene bullet.

I. Level of Care

Mr. McVeigh’s testimony here was given as part of his regular professional work,

rendering this factor technically inapplicable. Nonetheless, to the extent this factor can be

re-cast as a general inquiry into the level of care he exhibited, we have no qualms about

accepting the circuit court’s determination that Mr. McVeigh is a “consummate

professional in his field” and demonstrated a “level of care in this case” that was not

“assailed in any convincing manner.”

J. Relationship Between Reliability of Methodology and Opinion to

Be Offered

Based on the State’s evidence concerning the reliability of firearms examinations

and “a dearth of real-life examples of erroneous examinations,” the circuit court concluded

that “firearm and toolmark evidence is known to reach reliable results” and, therefore, that

this final factor favors admission of the evidence. We do not question that firearms

identification is generally reliable, and can be helpful to a jury, in identifying whether

patterns and markings on “unknown” bullets or cartridges are consistent or inconsistent

with those on bullets or cartridges known to have been fired from a particular firearm. For

that reason, to the extent Mr. Abruquah suggests that testimony about the consistency of

55

such patterns and markings should be excluded, we disagree.31 It is also possible that

experts who are asked the right questions or have the benefit of additional studies and data

may be able to offer opinions that drill down further on the level of consistency exhibited

by samples or the likelihood that two bullets or cartridges fired from different firearms

might exhibit such consistency. However, based on the record here, and particularly the

lack of evidence that study results are reflective of actual casework, firearms identification

has not been shown to reach reliable results linking a particular unknown bullet to a

particular known firearm.

For those reasons, we conclude that the methodology of firearms identification

presented to the circuit court did not provide a reliable basis for Mr. McVeigh’s unqualified

opinion that four bullets and one bullet fragment found at the crime scene in this case were

fired from Mr. Abruquah’s Taurus revolver. In effect, there was an analytical gap between

the type of opinion firearms identification can reliably support and the opinion

Mr. McVeigh offered.32 Accordingly, the circuit court abused its discretion in permitting

Mr. McVeigh to offer that opinion.

31

As noted, Mr. Abruquah argues that the testimony of a firearms identification

examiner should be limited to opining, “at most, that a firearm cannot be excluded as the

source of the questioned projectile[.]” It is not entirely clear to us whether Mr. Abruquah

believes that testimony about the consistency of patterns and markings on bullets would be

permissible—and, indeed, necessary to establish the basis for an opinion that a firearm

cannot be excluded—or whether he believes that testimony about the consistency of such

patterns and markings goes too far and should be excluded. If the latter, we disagree for

the reasons identified.

32

Both dissenting opinions contend that we have been insufficiently deferential to

the trial court’s determination. Although they observe, quite correctly, that we do not ask

trial judges to play the role of “amateur scientists,” Dissenting Op. of Hotten, J. at 4

56

IV. HARMLESS ERROR

The State argues in the alternative that any error in admitting Mr. McVeigh’s

testimony was harmless. We disagree.

“The harmless error doctrine is grounded in the notion that a defendant has the right

to a fair trial, but not a perfect one.” State v. Jordan, 480 Md. 490, 505 (2022). The

doctrine is strictly limited only to “error[s] in the trial process itself” that may warrant

reversal. Id. at 506 (quoting Weaver v. Massachusetts, 137 S. Ct. 1899, 1907 (2017)). For

an appellate court to conclude that the admission of expert testimony was harmless, the

State must show “beyond a reasonable doubt, that the error in no way influenced the

verdict.” Dionas, 436 Md. at 108 (quoting Dorsey, 276 Md. at 659).

Upon our review of the record, we are not convinced beyond a reasonable doubt

that the expert testimony in no way contributed to the guilty verdict. The firearm and

toolmark identification evidence was the only direct evidence before the jury linking

Mr. Abruquah’s gun to the crime. Absent that evidence, the guilty verdict rested upon

circumstantial evidence of a dispute between the men, a witness who heard gunfire around

the time of the dispute, a firearm recovered from the residence, and testimony of a jailhouse

(quoting Rochkind, 471 Md. at 33-34); Dissenting Op. of Gould, J. at 1, 50, we also do not

provide increased deference simply because the subject matter of the expert testimony is

scientific. The forensic technique under review was, until relatively recently, accepted

almost entirely without critical analysis. See discussion above at 16-17. Daubert and

Rochkind demand more than adherence to an orthodoxy simply because it has long been

accepted or because of the number of impressive-sounding statistics generated by studies

that do not establish the reliability of the specific testimony offered. They require that the

party proffering such evidence, whatever type of evidence it is, establish that it meets a

minimum threshold of reliability.

57

informant. To be sure, that evidence is strong. But the burden of showing that an error

was harmless is high and we cannot say, beyond a reasonable doubt, that the admission of

the particular expert testimony at issue did not influence or contribute to the jury’s decision

to convict Mr. Abruquah. See Clemons v. State, 392 Md. 339, 372 (2006) (stating that

“[l]ay jurors tend to give considerable weight to ‘scientific’ evidence when presented by

‘experts’ with impressive credentials” (quoting Reed v. State, 283 Md. 374, 386 (1978))).

CONCLUSION

Based on the evidence presented at the hearings, we hold that the circuit court did

not abuse its discretion in ruling that Mr. McVeigh could testify about firearms

identification generally, his examination of the bullets and bullet fragments found at the

crime scene, his comparison of that evidence to bullets known to have been fired from

Mr. Abruquah’s Taurus revolver, and whether the patterns and markings on the crime scene

bullets are consistent or inconsistent with the patterns and markings on the known bullets.

However, the circuit court should not have permitted the State’s expert witness to opine

without qualification that the crime scene bullets were fired from Mr. Abruquah’s firearm.

Because the court’s error was not harmless beyond a reasonable doubt, we will therefore

58

reverse the circuit court’s ruling on Mr. Abruquah’s motion in limine, vacate

Mr. Abruquah’s convictions, and remand for a new trial.

RULING ON MOTION IN LIMINE

CONCERNING EXPERT TESTIMONY

REVERSED; JUDGMENT OF THE

CIRCUIT COURT FOR PRINCE

GEORGE’S COUNTY VACATED; CASE

REMANDED FOR A NEW TRIAL. COSTS

TO BE PAID BY PRINCE GEORGE’S

COUNTY.

59

Circuit Court for Prince George’s County

Case No. CT121375X

Argued: October 4, 2022 IN THE SUPREME COURT

OF MARYLAND*

No. 10

September Term, 2022

__________________________________

KOBINA EBO ABRUQUAH

v.

STATE OF MARYLAND

__________________________________

Fader, C.J.,

Watts,

Hotten,

Booth,

Biran,

Gould,

Eaves,

JJ.

__________________________________

Dissenting Opinion by Hotten, J., which

Eaves, J., joins.

__________________________________

Filed: June 20, 2023

*During the November 8, 2022 general election, the voters of Maryland ratified a

constitutional amendment changing the name of the Court of Appeals to the Supreme Court

of Maryland. The name change took effect on December 14, 2022.

Respectfully, I dissent. I would hold that the Circuit Court for Prince George’s

County did not abuse its discretion in admitting the State’s expert firearm and toolmark

identification testimony and evidence, following its analysis and consideration of the

factors outlined in Rochkind v. Stevenson, 471 Md. 1, 236 A.3d 630 (2020). “When the

basis of an expert’s opinion is challenged pursuant to Maryland Rule 5-702, the review is

abuse of discretion.” Id. at 10, 236 A.3d at 636 (citation omitted); State v. Matthews, 479

Md. 278, 305, 277 A.3d 991, 1007 (2022) (citation omitted). We have declared it “the rare

case in which a Maryland trial court’s exercise of discretion to admit or deny expert

testimony will be overturned.” Matthews, 479 Md. at 286, 306, 277 A.3d at 996, 1008.

This should not be one of those instances.

The Circuit Court Did Not Abuse Its Discretion in Admitting the State’s Firearm

Toolmark Identification Testimony Under Rochkind.

In Rochkind, this Court abandoned the Frye-Reed standard in favor of the more

“flexible” analysis set forth in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S.

579, 113 S. Ct. 2786 (1993), concerning the admissibility of expert testimony. Rochkind,

471 Md. at 29, 34, 236 A.3d at 646, 650. Rochkind prescribes ten factors for trial judges

to consider when applying Maryland Rule 5-702.1 See id. at 35, 236 A.3d at 650 (emphasis

added). First, the trial court must consider the original five Daubert factors:

1

Rule 5-702 pertains to the admissibility of expert testimony and provides, in full:

Expert testimony may be admitted, in the form of an opinion or otherwise, if

the court determines that the testimony will assist the trier of fact to

understand the evidence or to determine a fact in issue. In making that

determination, the court shall determine[:]

(continued . . .)

(1) whether a theory or technique can be (and has been) tested;

(2) whether a theory or technique has been subjected to peer review and

publication;

(3) whether a particular scientific technique has a known or potential rate of

error;

(4) the existence and maintenance of standards and controls; and

(5) whether a theory or technique is generally accepted.

Id., 236 A.3d at 650 (quoting Daubert, 509 U.S. at 593–94, 113 S. Ct. 2786). Next, “courts

have developed additional factors for determining whether expert testimony is sufficiently

reliable[,]” including:

(6) whether experts are proposing to testify about matters growing naturally

and directly out of research they have conducted independent of the

litigation, or whether they have developed their opinions expressly for

purposes of testifying;

(7) whether the expert has unjustifiably extrapolated from an accepted

premise to an unfounded conclusion;

(8) whether the expert has adequately accounted for obvious alternative

explanations;

(. . . continued)

(1) whether the witness is qualified as an expert by knowledge, skill,

experience, training, or education,

(2) the appropriateness of the expert testimony on the particular subject, and

(3) whether a sufficient factual basis exists to support the expert testimony.

“[S]ufficient factual basis” includes two subfactors: “(1) an adequate supply of data; and

(2) a reliable methodology.” Rochkind, 471 Md. at 22, 236 A.3d at 642 (citation omitted).

Without either, the expert’s testimony is considered to be mere “speculation or conjecture.”

Id., 236 A.3d at 642 (internal quotations and citation omitted).

2

(9) whether the expert is being as careful as he [or she] would be in his [or

her] regular professional work outside his [or her] paid litigation consulting;

and

(10) whether the field of expertise claimed by the expert is known to reach

reliable results for the type of opinion the expert would give.

Id. at 35–36, 236 A.3d at 650 (quoting Fed. R. Evid. 702 Advisory Committee Note).

We adopted Rochkind to “refine” and “streamline the evaluation of scientific expert

testimony under [Md.] Rule 5-702.” Id. at 30, 35, 236 A.3d at 647, 650. As a threshold

matter, scientific testimony must be relevant and reliable. Id. at 14, 236 A.3d at 638

(citation omitted). Rochkind provided more flexibility for the gatekeeping mechanism of

ascertaining whether the expert evidence should be admitted in its analytical shift to a

“reliability” standard (Daubert), as opposed to “general acceptance” (Frye-Reed). The

Rochkind elements “provide guidance on how to determine if scientific reasoning is,

indeed, sound, or a scientific theory adequately justifies an expert’s conclusion.” Id. at 33,

236 A.3d at 649. “[A]ll of the Daubert factors are relevant to determining the reliability

of expert testimony, yet no single factor is dispositive in the analysis. A trial court may

apply some, all, or none of the factors depending on the particular expert testimony at

issue.” Id. at 37, 236 A.3d at 651 (emphasis added) (citation omitted). As the U.S.

Supreme Court recognized, “Daubert’s list of specific factors neither necessarily nor

exclusively applies to all experts or in every case. Rather, the law grants a [trial] court the

same broad latitude when it decides how to determine reliability as it enjoys in respect to

its ultimate reliability determination.” Kumho Tire Co. v. Carmichael, 526 U.S. 137, 141–

42, 119 S. Ct. 1167, 1171 (1999) (emphasis added) (citation omitted); Matthews, 479 Md.

3

at 314, 277 A.3d at 1012 (quoting Kumho Tire, 526 U.S. at 141–42, 119 S. Ct. at 1171);

Rochkind, 471 Md. at 37, 236 A.3d at 651 (quoting Kumho Tire, 526 U.S. at 141–42, 119

S. Ct. at 1171); Savage v. State, 455 Md. 138, 178, 166 A.3d 183, 206 (2017) (“[A] trial

court is not required to consider any or all of the Daubert factors in making its reliability

determination—they were ‘meant to be helpful, not determinative.’” (Adkins, J.,

concurring) (quoting Kumho Tire, 526 U.S. at 151, 119 S. Ct. at 1175)). Trial judges,

therefore, assume the critical role as “gatekeepers” against unreliable scientific evidence.

Rochkind, 471 Md. at 38, 236 A.3d at 652; Matthews, 479 Md. at 322, 277 A.3d at 1017

(citation omitted); Daubert, 509 U.S. at 597, 113 S. Ct. at 2798; Gen. Elec. Co. v. Joiner,

522 U.S. 136, 142, 118 S. Ct. 512, 517 (1997); Kumho Tire, 526 U.S. at 147, 119 S. Ct. at

1174 (noting that Daubert’s gatekeeping function also applies to expert testimony); Victor

E. Schwartz, Expert Testimony Needs Judges to Act As “Gatekeepers”: The Maryland

Court of Appeals Teaches Why, 13 J. Tort L. 229, 231 (2020).

Trial judges were provided these factors to assist in the evidence-based management

of their judicial gatekeeping function in criminal, civil, and equitable causes. The

gatekeeping function is significant, particularly for the ability of the finders of fact to

evaluate the scientific evidence and testimony and determine whether it should be accepted

or rejected in their ultimate determination. This Court has rejected the argument that judges

are “amateur scientists[:]”

[T]rial judges are not required to make a determination of the ultimate

scientific validity of any scientific propositions. Instead, they need only

make a much more limited inquiry: whether sufficient indicia of legitimacy

exist to support the conclusion that evidence derived from the principle may

be profitably considered by a fact finder at trial. We are confident that trial

4

judges are duly capable of undertaking the reliability analysis absent

scientific training.

Rochkind, 471 Md. at 34, 236 A.3d at 649 (emphasis added) (internal quotations and

citations omitted). “Applying these standards, we determine that the [circuit court’s]

decision in this case . . . was within its discretion and therefore lawful.” Kumho Tire, 526

U.S. at 142, 119 S. Ct. at 1171.

In light of the newly adopted Rochkind standard, the circuit court reconsidered the

admissibility of the firearm and toolmark identification expert evidence, known as the

AFTE methodology.2 The court examined the Rochkind factors “by way of the pleadings,

testimony and evidence presented during the 5-day hearing conducted prior to the second

jury trial, coupled with the supplemental hearing and pleadings conducted after the most

recent remand.” The court found that the State’s evidence for factors one, two, three, five,

six, eight, nine, and ten weighed in favor of admission. The evidence for factors four and

seven weighed against admission. Based on the Rochkind factors and the “totality of the

evidence and arguments presented,” the circuit court admitted the State’s firearms and

toolmark examination evidence.

As the majority notes, Mr. Abruquah argues on appeal that the State’s expert, Mr.

McVeigh, should have been “limited to opining, ‘at most, that a firearm cannot be excluded

as the source of the questioned projectile’” because the methodology is “insufficiently

reliable” to support Mr. McVeigh’s testimony. Maj. Op. at 38. To determine this “tailored”

2

The State’s expert, Mr. Scott McVeigh, uses the “AFTE method” to “compar[e]

microscopic markings on a bullet or cartridge case to make an ‘identification,’ i.e., to opine

that a specific firearm is the source of a fired ammunition component.”

5

issue of “whether the AFTE Theory can reliably support an unqualified opinion that a

particular firearm is the source of one or more particular bullets[,]” the majority conducts

its own Rochkind analysis. Id. at 38–39.

The majority holds that factors one, six, and nine weighs in favor of admission. Id.

at 39, 52–53, 55. Factors two, three, four, seven, eight, and ten, the majority concludes,

weighs against admission. Id. at 40, 45, 50, 54–56. The majority notes that factor five is

“neutral.” Id. at 52. Upon consideration of the factors, the majority determines that the

record, “on balance,” does not support Mr. McVeigh’s “unqualified testimony that the

crime scene bullets and bullet fragments were fired from Mr. Abruquah’s Taurus revolver.”

Id. at 45, 54. According to the majority, “the studies and other information in the record .

. . do not support the use of [the AFTE Theory] to reliably opine without qualification that

the bullets of unknown origin were fired from the particular firearm.” Id. at 54.

Specifically, the “firearms identification has not been shown to reach reliable results

linking a particular unknown bullet to a particular known firearm.” Id. at 56. The majority,

therefore, holds that “there was an analytical gap between the type of opinion firearms

identification can reliably support and the opinion Mr. McVeigh offered.” Id. (footnote

omitted). To the majority, this “gap should have foreclosed” Mr. McVeigh’s unqualified

testimony. Id. at 54.

I disagree, finding no error with the circuit court’s analysis. The concept of the

“analytical gap” originated in Joiner, 522 U.S. 136, 118 S. Ct. 512. Rochkind, 471 Md. at

43, 236 A.3d at 654 (Watts, J., dissenting). Over the years, it has become a “critical”

component in Maryland’s evidentiary analysis. Id. at 14, 236 A.3d at 638. As we’ve

6

explained, the role of the expert is to “connect[] the dots” or “provide[] a causal link”

between the data and/or science used by the expert and the expert’s ultimate conclusions.

See id. at 14–19, 236 A.3d at 638–40 (internal quotation marks and citations omitted). In

essence, an “analytical gap” results when the expert fails to “‘bridge’” the gap between the

expert’s opinion and “‘the empirical foundation on which the opinion was derived.’”

Matthews, 479 Md. at 317, 277 A.3d at 1014 (quoting Savage, 455 Md. at 163, 166 A.3d

at 198). In determining reliability, the trial judge “must also consider the relationship

between the methodology applied and conclusion reached.” Rochkind, 471 Md. at 36, 236

A.3d at 651. However, neither Daubert nor the Federal Rules of Evidence require trial

judges “‘to admit opinion evidence that is connected to existing data only by the ipse dixit

of the expert.’” Id., 236 A.3d at 651 (quoting Joiner, 522 U.S. at 144, 118 S. Ct. at 519).

“[T]he question then becomes: is this specific causation case . . . , where the analytical gap

was too vast, or a [] case where the analytical gap was sufficiently bridged?” Id. at 25, 236

A.3d at 644.

The circuit court thoroughly followed the Rochkind factors as prescribed by the U.S.

Supreme Court and this Court. Under the previous Frye-Reed standard, trial courts

determined whether an expert’s methodology was “generally accepted in the scientific

community.” Id. at 12–13, 236 A.3d at 637; Matthews, 479 Md. at 307, 277 A.3d at 1008

(“[P]rior to . . . Daubert [], the Frye ‘general acceptance’ test was the dominant standard

that courts used to determine the admissibility of novel scientific evidence.”). “Under

Daubert, judges are charged with gauging only the threshold reliability—not the ultimate

validity—of a particular methodology or theory.” Rochkind, 471 Md. at 33, 236 A.3d at

7

649 (emphasis added). In conducting the “reliability assessment,” courts are to consider

the non-exhaustive list of factors provided in Daubert. Matthews, 479 Md. at 307, 277

A.3d at 1008 (citing Daubert, 509 U.S. at 593–94, 113 S. Ct. at 2797). Trial courts are

granted “broad latitude to determine[]” “reliability in a particular case[.]” Kumho Tire,

526 U.S. at 153, 119 S. Ct. at 1176; Rochkind, 471 Md. at 37, 236 A.3d at 651 (quoting

Kumho Tire, 526 U.S. at 141–42, 119 S. Ct. at 1171). Thus, if “a trial court is satisfied that

an expert has applied a reliable methodology to an adequate supply of data, the court should

not exclude the expert’s testimony merely because the court is concerned that the expert’s

particular conclusions may be inaccurate.” Matthews, 479 Md. at 316, 277 A.3d at 1013.

While Rochkind requires trial judges to conduct an analysis under the Rochkind-

Daubert factors, this Court does not require trial judges to be “scientists” and arrive at a

conclusion with some measure of mathematical certainty. See Rochkind, 471 Md. at 33,

236 A.3d at 649; Daubert, 509 U.S. at 597, 113 S. Ct. at 2799 (“[T]he Rules of Evidence .

. . do assign to the trial judge the task of ensuring that an expert’s testimony both rests on

a reliable foundation and is relevant to the task at hand. Pertinent evidence based on

scientifically valid principles will satisfy those demands.”). As the U.S. Supreme Court

observed, “there are no certainties in science.” Daubert, 509 U.S. at 590, 113 S. Ct. at

2795 (citation omitted). Accordingly, a trial judge’s gatekeeping role isn’t to determine

whether the expert is “right” or “wrong;” rather, the judge’s role is to determine whether

the expert’s testimony is “adequately grounded in reliable and sound science, and that there

is not ‘too great an analytical gap’ between the expert’s methodology and conclusions.”

Schwartz, supra, at 233 (quoting Rochkind, 471 Md. at 36, 236 A.3d at 651); Maj. Op. at

8

9. This is exactly what the circuit court did when it recognized Mr. Abruquah’s “Herculean

effort” in demonstrating “why the evidence should be heavily scrutinized, questioned and

potentially impeached[.]” While the court did not, however, expressly address an

“analytical gap,” it observed that “the crux” of Mr. Abruquah’s arguments “address

impeachment rather than admissibility.”

In Rochkind, we rejected the argument that the Rochkind-Daubert standard

“enable[d] judges to . . . ‘usurp[] the role of juries.’” Rochkind, 471 Md. at 33, 236 A.3d

at 649. The power to weigh the validity of the evidence still sits with the jury or fact finder.

Id., 236 A.3d at 649. While I recognize the importance of “published standards,” it is for

the jury or the factfinder to determine the validity of the methodology of the firearm

identification testimony presented—not the circuit court or this Court. Maj. Op. at 50;

Rochkind, 471 Md. at 33, 236 A.3d at 649. We reaffirmed this principle a year later in

State v. Matthews, acknowledging that “[t]he unknown degree of uncertainty concerning

the accuracy of [the expert testimony] went to the weight the jury should give to the expert

testimony, not to its admissibility.” 479 Md. at 313, 277 A.3d at 1012 (footnote omitted).

Here, the circuit court continuously reaffirmed this notion, stating that Mr. Abruquah’s

critiques of the firearm identification evidence “are more suited to the weight such evidence

should be given at trial.” (Emphasis added). In doing so, it fulfilled its obligation under

Rochkind.

The majority notes that Mr. McVeigh’s testimony “was the only direct evidence

before the jury linking Mr. Abruquah’s gun to the crime.” Maj. Op. at 57. “Absent that

evidence,” the majority observes that Mr. Abruquah’s “guilty verdict rested upon

9

circumstantial evidence[.]” Id. at 57. Accordingly, the majority concludes that the

admission of such testimony was not harmless because it “cannot say, beyond a reasonable

doubt, that the admission of the particular expert testimony at issue did not influence or

contribute to the jury’s decision to convict Mr. Abruquah.” Id. at 58. This is especially

so, the majority recognizes, because “[l]ay jurors tend to give considerable weight to

‘scientific evidence’ when presented by ‘experts’ with impressive credentials[.]” Id.

(quoting Clemons v. State, 392 Md. 339, 372, 896 A.2d 1059, 1078 (2006) (internal

quotations and citation omitted)).

Assuming, arguendo, that the circuit court erred in admitting Mr. McVeigh’s

testimony, such error was harmless considering the overwhelming circumstantial and

direct evidence of guilt tying Mr. Abruquah to the shooting. As the majority notes, the

responding officers left Mr. Abruquah and Mr. Aguirre-Herrera after their third response

to the men’s shared residence around 12:15 a.m. According to the officers, Mr. Aguirre-

Herrera appeared to be terrified of Mr. Abruquah. A nearby witness testified that he heard

gunshots between 11:30 p.m. and 12:30 a.m. During questioning, Mr. Abruquah told

police where to find his firearms in the men’s shared residence, including Mr. Abruquah’s

Taurus .38 Special revolver. The State also introduced into evidence the transcript of the

testimony of Cecil Muhammed, Mr. Abruquah’s jail cellmate. Mr. Muhammed testified

that, while they were incarcerated together, Mr. Abruquah confessed to shooting Mr.

Aguirre-Herrera with his Taurus .38 on the night in question. According to Mr.

Muhammed, Mr. Abruquah and Mr. Aguirre-Herrera were in a relationship, but Mr.

Aguirre-Herrera engaged in prostitution through Craigslist and conducted such business in

10

the men’s shared residence. Mr. Muhammed testified that this allegedly enraged Mr.

Abruquah and made him jealous. We recognize this evidence is circumstantial; yet, as the

majority itself observes, is “strong.” Maj. Op. at 58.

Trial judges provide jury instructions “to aid the jury in clearly understanding the

case, to provide guidance for the jury’s deliberations, and to help the jury arrive at a correct

verdict.” Stabb v. State, 423 Md. 454, 464, 31 A.3d 922, 928 (2011) (internal quotation

marks and citation omitted). As such, trial judges instruct juries that “[a] conviction may

rest on circumstantial evidence alone, on direct evidence alone, or on a combination of

circumstantial and direct evidence.” Taylor v. State, 473 Md. 205, 218 n.8, 249 A.3d 810,

818 n.8 (2021) (emphasis added) (internal quotation marks and citation omitted). “The law

makes no distinction between the weight to be given to either direct or circumstantial

evidence.” Maryland Criminal Pattern Jury Instructions (“MPJI-Cr”) 3:01 (Maryland State

Bar Association 2d ed. 2022). “‘Circumstantial evidence may support a conviction if the

circumstances, taken together, do not require the trier of fact to resort to speculation or

conjecture . . . . It must afford the basis for an inference of guilt beyond a reasonable

doubt.’” Beckwitt v. State, 477 Md. 398, 429, 270 A.3d 307, 325 (2022) (quoting Smith v.

State, 415 Md. 174, 185, 999 A.2d 986, 992 (2010)). Accordingly, even in a case relying

solely on circumstantial evidence, “the finder of fact has the ‘ability to choose among

differing inferences that might possibly be made from a factual situation[.]’” Smith, 415

Md. at 183, 999 A.2d at 991 (quoting State v. Smith, 374 Md. 527, 534, 823 A.2d 664, 668

(2003)).

11

“[A] fundamental principle underlying trial by jury is that the credibility of a witness

and the weight to be accorded the witness’ testimony are solely within the province of the

jury.” Fallin v. State, 460 Md. 130, 154, 188 A.3d 988, 1002 (2018) (internal quotation

marks and citation omitted); see also MPJI-Cr 3:10. MPJI-Cr 3:14 provides, in part, that

jurors should:

[C]onsider an expert’s testimony together with all the other evidence. . . .

You should give expert testimony the weight and value you believe it should

have. You are not required to accept an expert’s testimony, even if it is

uncontradicted. As with any other witness, you may believe all, part, or none

of the testimony of any expert.

(Emphasis added). In adopting Daubert, we reiterated this notion, affirming that “juries

will continue to weigh competing, but still reliable, testimony.” Rochkind, 471 Md. at 33,

236 A.3d at 649. We, therefore, cannot hold that the firearm evidence did or “did not

influence or contribute to the jury’s decision[.]” Maj. Op. at 58; Stokes v. State, 379 Md.

618, 638, 843 A.2d 64, 75 (2004) (“Jury deliberations are private and are to be conducted

in secret.” (citation omitted)). “We need not decide whether the jury could have drawn

other inferences from the evidence, refused to draw inferences, or whether we would have

drawn different inferences from the evidence.” Smith, 415 Md. at 184, 999 A.2d at 991

(citation omitted). The jury could have based its verdict upon a weighing of all the

evidence, including the scientific and circumstantial evidence. See MPJI-Cr 3:14; see also

Howling v. State, 478 Md. 472, 507, 274 A.3d 1124, 1144 (2022) (“[O]ur concern is only

whether the verdict was supported by sufficient evidence, direct or circumstantial, which

could fairly convince a trier of fact of the defendant’s guilt of the offenses charged beyond

a reasonable doubt.” (internal quotation marks and citations omitted)); State v. Manion,

12

442 Md. 419, 437, 112 A.3d 506, 517 (2015) (recognizing that “a rational trier of fact could

conclude, beyond a reasonable doubt, that” the defendant intended to commit a crime based

circumstantial evidence). Concluding otherwise, as the majority does here, minimizes the

importance of both the role of the jury and jury instructions if we expect juries to believe

that direct evidence, especially if it’s scientific evidence, provides any more persuasive

value than circumstantial evidence. See MPJI-Cr 3:01; see also Taylor, 473 Md. at 218

n.8, 249 A.3d at 818 n.8 (“No greater degree of certainty is required when the evidence is

circumstantial than when it is direct.” (internal quotation marks and citation omitted)).

The circuit court followed Rochkind within the letter of the law as prescribed. See

Matthews, 479 Md. at 305, 277 A.3d at 1007 (citing Jenkins v. State, 375 Md. 284, 296,

825 A.2d 1008, 1015 (2003)). Based upon the extensive hearings, pleadings, testimony,

and evidence presented, the circuit court was satisfied that the State met its burden to admit

the firearm identification expert evidence for consideration by the jury.3 Its decision was

neither “well removed from any center mark” nor “beyond the fringe of what [this] [C]ourt

3

The majority’s analysis is largely predicated on a consideration of the Daubert

factors. Maj. Op. at 39-56. While the majority recognizes that the factors “are neither

exhaustive nor mandatory,” its rationale seems to suggest otherwise. Id. at 39 (internal

quotation marks and citation omitted). As we expressed, the list of Daubert factors is not

exhaustive or mandatory. Kumho Tire, 526 U.S. at 141, 119 S. Ct. at 1171; Rochkind, 471

Md. at 36–37, 236 A.3d at 651 (internal quotation marks and citation omitted). The circuit

court had “broad latitude” to consider how to determine the reliability of the State’s firearm

and toolmark identification expert evidence. Kumho Tire, 526 U.S. at 141, 119 S. Ct. at

1171. In addition to its Daubert analysis, the circuit court considered other aspects of the

case expressed herein in making its ultimate reliability determination. It was within the

court’s discretion and capacity to do so as the gatekeeper. Id., 119 S. Ct. at 1171; Rochkind,

471 Md. at 36–37, 236 A.3d at 651 (internal quotation marks and citation omitted). “For

these [] reasons taken together, it concluded that [the] testimony was” admissible. Id. at

156, 119 S. Ct. at 1178.

13

deems minimally acceptable.” Id., 277 A.3d at 1007 (internal quotation marks and citation

omitted). The majority considers this “standard” to be “somewhat unfair.” Maj. Op. at 6

n.5. While it observes that “the circuit court acted deliberately and thoughtfully in

approaching, analyzing, and resolving the question before it[,]” the majority nonetheless

“c[a]me to a different conclusion concerning the outer bounds of what is acceptable expert

evidence in this area[]” and provides no guidance for the trial court in terms of what

standard applies. Id. at 6–7 n.5. This Court does not “reverse simply because [we] would

not have made the same ruling.” Devincentz v. State, 460 Md. 518, 550, 191 A.3d 373,

391 (2018) (emphasis added) (internal quotations and citation omitted). A reasonable

person would take the view adopted by the circuit court here. Williams v. State, 457 Md.

551, 563, 179 A.3d 1006, 1013 (2018). It was, therefore, within the realm of the jury, as

the triers of fact, to resolve the firearm toolmark analysis and opinion, along with the other

evidence presented, in rendering its verdict. See MPJI-Cr 3:14.

The majority’s holding blurs the role of the trial judge, allowing judges to “exclude

. . . legitimate opinions of experts[] that [] are for a jury to weigh credibility.” Rochkind,

471 Md. at 33, 236 A.3d at 649. The majority appears to conflate the role of the trial judge

as gatekeepers, with the evaluation of the science or the expert opinion that is presented for

consideration of its admissibility by the judge. That is not what Rochkind required. At the

time of Rochkind, we did not “foresee th[is] gloomy outlook.” Id., 236 A.3d at 649.

However, the majority’s decision does exactly that.

14

CONCLUSION

For these reasons, I respectfully dissent and would affirm the judgment of the

Circuit Court for Prince George’s County. Justice Eaves has authorized me to state that

she joins in this opinion.

15

Circuit Court for Prince George’s County

Case No. CT121375X

Argued: October 4, 2022 IN THE SUPREME COURT

OF MARYLAND*

No. 10

September Term, 2022

__________________________________

KOBINA EBO ABRUQUAH

v.

STATE OF MARYLAND

__________________________________

Fader, C.J.,

Watts,

Hotten,

Booth,

Biran,

Gould,

Eaves,

JJ.

__________________________________

Dissenting Opinion by Gould, J.

__________________________________

Filed: June 20, 2023

*During the November 8, 2022 general election, the voters of Maryland ratified a

constitutional amendment changing the name of the Court of Appeals to the Supreme Court

of Maryland. The name change took effect on December 14, 2022.

In Rochkind v. Stevenson, 471 Md. 1 (2020), this Court adopted the Daubert1

framework for the admission of expert testimony and embraced certain important

principles. Justice Hotten highlights these principles in her dissent, some of which I

reiterate here for context. Dissenting Op. of Justice Hotten 1-4.

First, the Daubert-Rochkind factors (“Daubert factors”) provide trial courts with a

flexible guide—not a mandatory scoresheet—for serving as gatekeepers with respect to

scientific or technical evidence. See, e.g., Rochkind, 471 Md. at 36-37; Daubert, 509 U.S.

at 589, 596.

Second, trial courts are not tasked with determining “the ultimate scientific validity

of any scientific propositions.” Rochkind, 471 Md. at 34 (quoting State v. Porter, 698 A.2d

739, 757 (Conn. 1997)). Instead, the trial court’s duty is far more modest—to determine

only “whether sufficient indicia of legitimacy exist to support the conclusion that evidence

derived from the principle may be profitably considered by a fact finder at trial.” Id. As

Justice Hotten reminds us, this Court emphasized that “[w]e are confident that trial judges

are duly capable of undertaking the reliability analysis absent scientific training.”

Dissenting Op. of Justice Hotten 4-5 (quoting Rochkind, 471 Md. at 34). We do not ask

judges to be “amateur scientists.” Id. at 4 (quoting Rochkind, 471 Md. at 33).

Third, we apply an abuse of discretion standard of review to the trial court’s

admission or exclusion of expert testimony. Rochkind, 471 Md. at 37. This deferential

posture is inextricably linked to our expectation that trial judges need only serve as

1

Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993).

gatekeepers: that is, we expect trial judges to make reasonable decisions based on the

evidence presented, not to become experts in their own right. If a trial court’s decision is

supported by competent evidence and untainted by a mistake of law, we defer to its

determination even if we would have reached a different conclusion. See State v.

Matthews, 479 Md. 278, 305 (2022) (quoting Devincentz v. State, 460 Md. 518, 550 (2018)

(we do “not reverse simply because . . . [we] would not have made the same ruling”)); Id.

at 306 (“[I]t is still the rare case in which a Maryland trial court’s exercise of discretion to

admit or deny expert testimony will be overturned.”).

This Court has articulated the abuse of discretion standard in several ways. We have

held that an abuse of discretion occurs “where no reasonable person would take the view

adopted by the circuit court,” Williams v. State, 457 Md. 551, 563 (2018); “when a trial

judge exercises discretion in an arbitrary or capricious manner or when he or she acts

beyond the letter or reason of the law[,]” Jenkins v. State, 375 Md. 284, 295-96 (2003); and

when “the trial court’s decision [is] ‘well removed from any center mark imagined by the

reviewing court and beyond the fringe of what that court deems minimally acceptable[,]’”

Devincentz, 460 Md. at 550 (quotation omitted). We reiterated these standards in

Matthews. 479 Md. at 305-06.

Although the Majority acknowledges the abuse of discretion standard, it suggests

that its application here is unfair “in the absence of additional caselaw from this Court

implementing the newly adopted standard[.]” Maj. Op. 6 n.5. The Majority thus sidesteps

the deferential standard of review by recasting its decision as establishing the “outer bounds

of what is acceptable expert evidence in this area.” See Maj. Op. 7 n.5.

2

This misses the mark. First, the Majority does not in practice establish any

boundaries for the admission of forensic firearms evidence. Second, though this Court has

not yet evaluated this type of evidence under Daubert, the Majority’s disagreement with

the trial court does not arise from a lack of judicial guidance. To the contrary, there is no

shortage of federal cases applying the Daubert factors to determine the reliability of the

Association of Firearm and Toolmark Examiners (“AFTE”) Theory of Identification (the

“AFTE Theory”),2 see Maj. Op. 14 n.8, some of which expressly considered the 2016

report issued by the President’s Council of Advisors on Science and Technology on the

scientific validity of forensic techniques, including firearms identification.3 At bottom, the

Majority simply disagrees with the trial court’s application of the Daubert factors and its

interpretation of the evidence—a classic de novo review.

That the Majority thinks the abuse of standard is unfair in this context does not

justify setting it aside and applying what is, in practice if not in name, a de novo standard

2

See, e.g., United States v. Brown, 973 F.3d 667, 702-04 (7th Cir. 2020) (affirming

admission of expert testimony that cartridge cases found in different locations matched and

acknowledging PCAST findings); United States v. Johnson, 875 F.3d 1265, 1280-81 (9th

Cir. 2017) (affirming admission of expert testimony that matched a bullet recovered from

crime scene to defendant’s pistol and acknowledging 2009 NAS report’s criticisms of the

AFTE Theory).

3

See EXECUTIVE OFFICE OF THE PRESIDENT, PRESIDENT’S COUNCIL OF ADVISORS

ON SCIENCE AND TECHNOLOGY, REPORT TO THE PRESIDENT, FORENSIC SCIENCE IN

CRIMINAL COURTS: ENSURING SCIENTIFIC VALIDITY OF FEATURE-COMPARISON

METHODS (Sept. 2016) (“PCAST” or the “PCAST Report”), available at

https://obamawhitehouse.archives.gov/sites/default/files/microsites/ostp/PCAST/pcast_fo

rensic_science_report_final.pdf (last accessed June 12, 2023) archived at

https://perma.cc/3QWJ-2DGR.

3

of review. If the abuse of discretion standard is not appropriate here, then we should

reconsider whether that standard is appropriate for reviewing Daubert decisions. But we

do not serve well the parties and trial judges who apply our decisions if we inconsistently

apply the standards of review to a trial court’s discretionary ruling.

Usually, when we hold that a trial court abuses its discretion, we identify what it did

wrong and explain how to do it properly going forward. See, e.g., State v. Robertson, 463

Md. 342, 365 (2019) (explaining the trial court’s error underlying abuse of discretion

holding and correcting the mistake for future cases); State v. Heath, 464 Md. 445, 462-65

(2019) (holding that the trial court abused its discretion, and explaining how the abuse

occurred and how it could be avoided in future cases). Not so today. Though the Majority

cabins its analysis to the record here and acknowledges that trial courts may consider other

studies in future cases, Maj. Op. 9-10 & 10 n.6, the Majority fails to instruct trial courts

how to determine the levels at which the accuracy, repeatability, reproducibility, and

inconclusive determination rates of firearm identification would be sufficiently reliable for

the evidence to be “profitably considered by a fact finder at trial,” Rochkind, 471 Md. at

34. From the Majority’s opinion today, trial courts can only glean that these metrics, based

on the studies discussed by the Majority, fail to establish reliability. The Majority’s

opinion leaves trial courts rudderless at sea in evaluating this type of evidence henceforth.

As discussed below, the focus of our inquiry should not be the reliability of the

AFTE Theory in general, but rather the reliability of conclusive determinations produced

when the AFTE Theory is applied. Of course, an examiner applying the AFTE Theory

might be unable to declare a match (“identification”) or a non-match (“elimination”),

4

resulting in an inconclusive determination. But that’s not our concern. Rather, our concern

is this: when the examiner does declare an identification or elimination, we want to know

how reliable that determination is. The record shows that conclusive determinations of

either kind (identification or elimination) are highly reliable. So, given the record before

it, the trial court here made a ruling well within the bounds of its considerable discretion.

I join Justice Hotten’s dissent but write separately to explain how the evidence at

the center of the Majority’s analysis was sufficient to support the trial court’s admission of

Scott McVeigh’s unqualified opinion that bullets recovered from the murder scene were

fired from Mr. Abruquah’s Taurus revolver.4 In so doing, I assume familiarity with the

defined terms and discussion of the various studies (Ames I and II, 5 in particular) in the

Majority’s opinion.

I.

PCAST

Before delving into the results of Ames I and Ames II, the two studies that garnered

the lion’s share of the Majority’s attention, we should recognize that the trial court was

4

I join Justice Hotten’s dissent on the issue of whether the trial court abused its

discretion in admitting Mr. McVeigh’s unqualified opinion, but not as to harmless error.

In that regard, I agree with the Majority that, to the extent that Mr. McVeigh’s opinion was

inadmissible, the error would not be harmless.

5

See generally David P. Baldwin, et al., A Study of False-Positive and False

Negative Error Rates in Cartridge Case Comparisons, U.S. DEP’T OF ENERGY (2014)

(“Ames I”); Stanley J. Bajic, et al., Report: Validation Study of the Accuracy, Repeatability,

and Reproducibility of Firearm Comparisons, U.S. DEP’T OF ENERGY 1-2 (2020) (“Ames

II”).

5

presented with at least three other studies also supporting the conclusion that the AFTE

Theory could reliably link bullets to specific guns.6

The Majority, however, finds limited value in all studies but Ames I and II. In

discounting these other studies, the Majority relies heavily on criticisms made by

This text is long and has been trimmed here. Open the source document for the complete record.