Court Opinion

ID: 6334866
Source: CourtListenerOpinion
Date Created: 2022-04-26 13:06:22.568217+00
Date Added: 2024-06-11T09:23:42.894297
License: Public Domain

State of New York                                                    OPINION
Court of Appeals                                      This opinion is uncorrected and subject to revision
                                                        before publication in the New York Reports.

 No. 3
 The People &c.,
         Respondent,
      v.
 John Wakefield,
         Appellant.

 Matthew C. Hug, for appellant.
 Peter H. Willis, for respondent.

 DiFIORE, Chief Judge:

        This appeal primarily concerns the admissibility of DNA mixture interpretation

 evidence generated by the TrueAllele Casework System. We conclude that Supreme Court

                                         -1-
                                             -2-                                      No. 3

did not abuse its discretion in finding, following a Frye hearing, that TrueAllele’s use of

the continuous probabilistic genotyping approach to generate a statistical likelihood ratio—

including the use of peak data below the stochastic threshold—of a DNA genotype is

generally accepted in the relevant scientific community. We also hold that there was no

error in the court’s denial of defendant’s request for discovery of the TrueAllele software

source code in connection with the Frye hearing or for the purpose of his Sixth Amendment

right to confront the witness against him at trial.

                                              I.

       On April 12, 2010, the victim was found strangled to death in his apartment, with a

guitar amplifier cord wrapped around his neck. Several items had been stolen from the

victim’s home, including a PlayStation 3, a laptop and a distinctive orange duffel bag.

Witnesses observed defendant in the company of the victim the weekend of the homicide

and defendant admitted to three individuals that he had choked the victim. Defendant did

not dispute that he had been present at the victim’s home. A separate witness observed

defendant with a distinctive orange duffel bag like the one belonging to the victim,

attempting to trade a PlayStation and a laptop for drugs. The victim’s PlayStation 3 was

recovered from the home of a local drug dealer.

At the scene, the police collected DNA samples from several items of evidence and sent

them to the New York State Police Forensic Investigation Center (Lab) for PCR DNA

                                             -2-
                                             -3-                                         No. 3

typing analysis, using the FBI-selected 15 STR loci standard.1 Defendant’s single-source

DNA profile was developed from two bottles taken from the victim’s home. Relevant to

the issues presented here are four DNA profiles developed by the Lab through the samples

taken from the front and rear outside collar of the victim’s shirt, the victim’s dorsal forearm

and a section of the amplifier cord used to strangle the victim. The DNA test results

developed by the Lab in an electropherogram were then compared to known DNA profiles

from defendant and the victim. The Lab concluded that: 1) the two profiles generated from

the shirt collar were consistent with at least two donors, one of which was the victim, and

defendant could not be excluded as the other contributor; 2) the DNA mixture from the

right dorsal forearm was consistent with DNA from the victim, as the major contributor,

mixed with at least two additional donors; and 3) the amplifier cord was a mixture of at

least two donors, from which the victim could not be excluded as a possible contributor.

The results generated from the amplifier cord were not compared to defendant’s DNA

profile because of the complexity of the mixture.

       Since the Lab used an interpretation standard of a stochastic threshold of 50 to 100

relative fluorescence units (RFU), the analyst did not call any alleles based on peaks on the

electropherogram below that threshold. As a result, there was insufficient data to allow the

1
  Briefly, as we have previously explained in greater detail, PCR, or polymerase chain
reaction DNA typing “analyzes DNA in the form of alleles that are found at the same
location (locus) of the DNA on homologous (matching) chromosomes” (People v John, 27
NY3d 294, 298 [2016]; see also People v Williams, 35 NY3d 24, 46-47 [2020]). In the
samples at issue, the Lab used electrophoresis to test for 15 specific short tandem repeat
(STR) locations, or loci, as well as the sex-determining amelogenin locus (see 27 NY3d at
298). The reliability of the electrophoresis is not contested here.
                                             -3-
                                            -4-                                        No. 3

Lab to calculate probabilities for the unknown contributors to the DNA mixtures found on

the amplifier cord and the front of the shirt collar. The Lab was able to call only 4 out of

15 STR loci and the analyst, using the combined probability of inclusion method, 2

generated a statistic that the probability an unrelated individual contributed DNA to the

outside rear shirt collar was 1 in 1,088. Using the same number of loci for the profile

obtained from the victim’s forearm, the analyst generated a statistic that the probability an

unrelated individual contributed DNA to the profile was 1 in 422.

       The electronic data from the DNA testing of the four samples at issue was then sent

to Cybergenetics for additional analysis because its TrueAllele Casework System applies

a continuous probabilistic genotyping method of calculating a likelihood ratio—using all

of the information generated on the electropherogram, including peaks that fall below a

laboratory’s stochastic threshold. The likelihood ratio in its modern form was developed

by Alan Turing during World War II as a code-breaking method. TrueAllele uses a

probability model to assess the values of a genotype objectively. It does not consider a

reference sample for any particular DNA profile. Following protocol, once the genotypes

were inferred based on mathematical computations from all the data in the

electropherograms, the system compared defendant’s genotype to all of the statistical

genotype possibilities and calculated likelihood ratios as to the presence of defendant’s

2
  The combined probability of inclusion method relies on the alleles at the combined loci
called by an analyst and then calculates the probability that a random person’s DNA is
included in the mixture by determining how often each allele occurs in the general
population.
                                            -4-
                                            -5-                                         No. 3

genotype. The ratios were exponentially greater than those generated by the methods

employed by the Lab. Specifically, TrueAllele concluded that it was 5.88 billion times

more probable that defendant was a contributor to the mixture on the amplifier cord than

an unrelated black person, that it was 170 quintillion times more probable that defendant

was a contributor to the mixture on the outside rear shirt collar than an unrelated black

person, that it was 303 billion times more probable that defendant was a contributor to the

mixture on the outside front shirt collar than an unrelated black person, and that it was 56.1

million times more probable that defendant was a contributor to the mixture on the victim’s

dorsal forearm than an unrelated black person.

       Prior to trial, in March 2014, defendant moved to preclude the introduction of any

evidence or testimony derived from the TrueAllele Casework System or, in the alternative,

for a Frye hearing to determine the general acceptance of TrueAllele in the relevant

scientific community. Defense counsel acknowledged having received from the People

approximately 1,500 pages of discovery documents, including reports relating to the DNA

analysis, but argued that several additional items “must be disclosed”—specifically, the

defense sought the “assumptions” and parameters programmed into the TrueAllele system

and the software’s source code.

       In support of the motion, defendant submitted an affidavit from Ranajit

Chakraborty, Ph.D.—a member of the Scientific Working Group on DNA Analysis

                                            -5-
                                           -6-                                        No. 3

Methods (SWGDAM)3 and former member of the New York State Commission on

Forensic Science DNA Subcommittee. Parenthetically, the DNA subcommittee is charged

by Executive Law § 995-b (13) to “assess and evaluate all DNA methodologies proposed

to be used for forensic analysis” in the state. Dr. Chakraborty acknowledged that both New

York’s DNA Subcommittee and the full Commission on Forensic Science (CFS) approved

TrueAllele for forensic casework without limitation in 2011 while he was a member.

However, since TrueAllele “re-analyzes” the electronic data from another laboratory by

including “all allele peak height information including that which extends below” the

stochastic threshold, he maintained that it was a novel innovation which had not gained

general acceptance in the scientific community. Dr. Chakraborty opined that, when the

DNA Subcommittee approved TrueAllele, it had not been presented with evidence of its

ability to analyze certain types of complex DNA mixtures and that it “ha[d] not been

adequately validated for the type of casework [to which] it is now being applied.” Dr.

Chakraborty contended that, in the absence of disclosure of the source code for the software

and the underlying assumptions programmed into the system, “TrueAllele cannot be

meaningfully validated.”

       Supreme Court granted defendant’s motion to the extent of ordering a Frye hearing

to determine the admissibility of TrueAllele’s methodology.

3
  SWGDAM serves as a forum for evaluating forensic biology methods and research in
order to enhance forensic biology services and provides recommendations to the FBI
Director for the Quality Assurance Standards for forensic DNA analysis
(https://www.swgdam.org/bylaws [last accessed April 18, 2022]).
                                           -6-
                                           -7-                                        No. 3

       In July 2014, prior to the Frye hearing, defense counsel made a supplemental

demand for discovery seeking several items relating to the TrueAllele process including,

as relevant here, the TrueAllele source code. The People, who were not in possession of

the source code, denied the request as the source code was outside the scope of the former

demand discovery provision, CPL 240.20.

       The Frye hearing commenced in October 2014 and the People called three

witnesses—Dr. Mark Perlin from Cybergenetics, and Dr. Barry Duceman and forensic

analyst Jay Caponera from the Lab. Dr. Perlin, who has a medical degree as well as a Ph.D.

in both mathematics and computer science, founded Cybergenetics in 1994 and is its Chief

Scientist and Executive Officer.     He testified that TrueAllele is comprised of two

systems—TrueAllele Databank, for interpreting single-source reference samples (used by

the New York State Police for the state DNA databank), and TrueAllele Casework, for

interpreting more complex DNA mixtures. The True Allele Casework System does not

generate a DNA profile, but analyzes the electronic raw data that has already been

generated by a forensic crime lab, separates (or deconvolutes) the genotypes and calculates

the likelihood ratio.4 As described at the hearing, the analyst operating the TrueAllele

system reviews the raw electronic data and then inputs the data file into the computer,

setting parameters such as the number of contributors and the quality of the mixture. The

4
  The computer divides the genotype probability for an allele by the rate at which it occurs
in the general population, using genotype information from the FBI database, and thereby
derives the match statistic for a locus. The same calculation is made at each locus and they
can be multiplied together to calculate the likelihood ratio or “how much more the suspect
matches the evidence than a random person would.”
                                           -7-
                                            -8-                                        No. 3

computer then separates the genotypes using the mathematical probability principle of the

Markov chain Monte Carlo (MCMC) search to calculate the probability for what the

different genotypes could be. The computer conducts a quantitative analysis using all of

the electronic data generated in the electropherogram—including patterns and peak

heights—as opposed to the qualitative analysis of visual human review, which has a limited

data field due to the laboratory’s stochastic level.5 Through the mathematical process, the

system makes an inference based on the probability of each possibility of the alleles at each

locus, then records the genotypes and mixture weights for each contributor. The analyst

then looks at the results to determine whether the computer has achieved “concordance”

and, if not, the analyst has the option to take additional steps—i.e., ask the computer to

model for another donor, allow it to run more cycles or ask it to account for degradation in

the sample.

       As to general acceptance of the continuous probabilistic genotyping system, the

testimony of the People’s witnesses established that probabilistic genotyping methods have

been recognized by the relevant scientific community such as SWGDAM, the American

5
  Under the 2010 SWGDAM guidelines, a laboratory using a probabilistic genotyping
approach, rather than a stochastic threshold, required empirical data and internal validation
of the software by the laboratory. Both Dr. Duceman and Caponera testified at the Frye
hearing to their compliance with controlling laboratory standards and to the Lab’s
“intensive validation” of TrueAllele casework, including validation studies conducted after
the approval of TrueAllele in 2011 by the CFS. Shortly after the trial in this case,
SWGDAM issued guidelines for the prospective validation of probabilistic genotyping
systems
(https://www.swgdam.org/_files/ugd/4344b0_22776006b67c4a32a5ffc04fe3b56515.pdf
[last accessed April 18, 2022]). The concurrence’s consideration and independent
evaluation of the test in these subsequently issued guidelines is inappropriate.
                                            -8-
                                             -9-                                         No. 3

National Standards Institute and the National Institute of Standards and Technology (NIST)

as a valid approach to DNA interpretation—including the fully continuous probabilistic

genotyping approach used by TrueAllele. The mathematical and scientific principles

underlying the system (MCMC and Bayes’ theorem) are well-established and independent

validation of the reliability of the software is available in the form of a free trial that can

be used to verify a known sample. Dr. Perlin has presented on the DNA mixture

interpretation of TrueAllele at multiple scientific conferences, including internationally,

and TrueAllele Casework has been the subject of numerous peer-reviewed published

articles in scientific journals. The TrueAllele Casework System had also undergone

approximately 25 validation studies—one involving samples created by NIST. Although

Dr. Perlin was involved in and coauthored most of the validation studies, his interest in

TrueAllele was disclosed as required by the journals who published the studies and the

empirical evidence of the reliability of TrueAllele was not disputed. Four validation

studies were conducted independently by laboratories.

       Two of the independent validation studies were conducted by the New York State

Police Lab and were designed to conform to the quality assurance standards of the FBI in

order to maintain the Lab’s access to the national DNA CODIS database. Jay Caponera

testified that he performed the validation studies using complex mixtures of up to four

contributors and varying amounts of DNA, including low template samples.6 The system

6
  The validation studies established that TrueAllele generated accurate and reproducible
results with as little as 15.6 picograms of DNA. Below that level and with more complex
mixtures, more variation was found in the results.
                                             -9-
                                           - 10 -                                      No. 3

was able to separate the known donor samples from the unrelated profiles provided by staff

members—demonstrating that it provides both inculpatory and exculpatory results. In

sum, the validation studies found the results generated by TrueAllele were reliable as they

were sensitive (identifies the correct person), specific (excludes noncontributors), accurate

and reproducible.

       The evidence at the hearing further established that NIST used the TrueAllele

system to examine the composition and assess the weights of a two-person mixture for its

standard reference materials (used by other laboratories to conduct quality assurance).7

Evidence generated by TrueAllele had also been found admissible after hearings conducted

in states outside New York, as well as other countries. In addition, the system was used to

conduct all forensic casework in the State of Virginia and in Kern County, California.

       Defendant did not call an expert witness or introduce any evidence at the hearing.

He also did not refute the fundamental mathematical principles of the methodology used

by TrueAllele. Rather, in cross-examining the People’s witnesses, the defense focused on

the fact that the TrueAllele system involves artificial intelligence in its mathematical

application by drawing inferences on the data, the “black box” nature of the technology

and the small number of independent validation studies conducted without Dr. Perlin’s

involvement. The defense also emphasized that most forensic laboratories still used the

7
 As the hearing court noted, NIST is “the scientific wing of the United States Department
of Commerce, whose mission is to advocate science in the United States and guide the
forensic DNA community” (47 Misc 3d 850, 858 [Sup Ct, Schenectady County 2015]).

                                           - 10 -
                                            - 11 -                                     No. 3

stochastic threshold model. Defendant elicited that some laboratory analysts lack a

complete understanding of how the sophisticated mathematical system works and that Dr.

Perlin characterized the “main barrier” to implementing the continuous method as the

difficulty in educating analysts on the system to the degree they would be able to testify in

court.8

          Following the hearing, in a lengthy and detailed opinion, Supreme Court found that

TrueAllele was generally accepted in the relevant scientific community and denied

defendant’s motion to preclude testimony and evidence derived therefrom (47 Misc 3d at

859). The court concluded that the quantitative analysis performed by TrueAllele had been

empirically tested and found to be reliable and accurate, that it was the subject of

publication in scientific journals and favorable peer review, that it was more efficacious

than human review using the stochastic method, that it had been validated and the results

were reproducible, and that the scientific and mathematical principles upon which it was

based had been accepted by the relevant scientific community long ago. The court

observed that, notwithstanding that TrueAllele had been in existence since 1999, there was

a lack of negative critical work concerning its methods in the scientific community.

                                              II.

8
  The court reopened the Frye hearing, following a Brady disclosure by the People, to hear
testimony about allegations of cheating on TrueAllele proficiency tests in the Lab. The
testimony established that the suspected individuals were not involved in any way in the
Lab’s validation studies.
                                            - 11 -
                                             - 12 -                                       No. 3

       Prior to trial, defendant moved for disclosure of the source code in order “to

meaningfully exercise his constitutional right to confront his accusers.” He argued that the

report generated by TrueAllele was testimonial, that the computer program was the

functional equivalent of a laboratory analyst and that the source code was the witness that

must be produced to satisfy his right to confrontation. He claimed that Perlin’s “surrogate”

trial testimony without disclosure of the source code was inadequate—“the TrueAllele

Casework System source code itself, and not Dr. Perlin, is the declarant with whom

[defendant] has a right to be confronted.” The court denied the motion, finding that the

source code was not a witness or testimonial in nature, and that defendant would have the

opportunity to confront and cross-examine Dr. Perlin—the analyst and the developer of the

software.

       Defendant again raised his confrontation argument prior to Dr. Perlin’s trial

testimony, asserting that the TrueAllele Casework System was the witness and that he

needed the source code to effectively cross-examine that witness.                When the court

questioned how one cross-examines a computer program, defendant represented that, once

his experts had the opportunity to review the source code, he would then pose questions to

Dr. Perlin based on the experts’ review. The court denied the request, stating that the issue

defense counsel raised was a discovery issue and that defendant’s ability to cross-examine

Dr. Perlin, the developer of the source code, satisfied his right to confrontation.

       Both Dr. Perlin and the analyst from the Lab who conducted the electrophoresis

testified at trial to the results of the DNA testing and statistical analysis.

                                             - 12 -
                                           - 13 -                                     No. 3

       Gary Skuse, Ph.D., a professor of biological sciences at the Rochester Institute of

Technology, testified at trial as a defense witness. After reviewing 1,278 pages of

documents relating to the DNA testing in this case, including the electropherograms, Skuse

agreed with the DNA interpretation analysis that defendant’s DNA was present in the

mixtures found on the shirt collar and amplifier cord and that it was “most likely” present

on the victim’s forearm. Skuse opined, however, that the DNA may have been present as

a result of secondary transfer (not directly from defendant).

       The jury convicted defendant of murder in the first degree and robbery in the first

degree.

       The Appellate Division affirmed (175 AD3d 158 [3d Dept 2019]). The Court held

that Supreme Court properly concluded that TrueAllele was generally accepted in the

relevant scientific community and rejected defendant’s argument that disclosure of the

TrueAllele source code was required to properly conduct the Frye hearing. The Court

noted that “[t]he record reflects that articles evaluating TrueAllele have been published in

six separate forensics journals”; “TrueAllele had undergone approximately 25 validation

studies, some of which appeared in peer-reviewed publications”; “[t]he DNA

Subcommittee of the New York State Forensic Science Commission offered a binding

recommendation that TrueAllele be used by the State Police for its forensic casework” and

it was later approved by the full Commission; and “[a]t the time of the Frye hearing,

TrueAllele had also been used in various states and had been deemed admissible in

Virginia, Pennsylvania and California” (175 AD3d at 162-163). As to defendant’s claim

                                           - 13 -
                                           - 14 -                                      No. 3

that the failure to disclose the TrueAllele source code violated his constitutional right to

confrontation, the Court concluded that the report generated by TrueAllele was testimonial

in nature, but that the source code was not a declarant. The Court cited Dr. Perlin’s

explanation at the Frye hearing that

“there is human input when utilizing TrueAllele[, including that] a human
analyst tells the computer what to download and under what conditions to
analyze the data, the analyst tells the computer what questions to ask when
interpreting the data and the analyst downloads certain results from the
computer, the analyst determines how many ‘runs,’ or cycles, of the data the
system will complete and the analyst then makes comparisons to form the
likelihood ratios” (175 AD3d at 169).

The Court further observed that defendant had the opportunity to confront Dr. Perlin, “his

true accuser,” at trial and that defendant did not preserve the alternative argument that the

failure to disclose the source code impaired his ability to cross-examine Dr. Perlin as the

declarant (175 AD3d at 170).

       In a concurring opinion, one Justice opined that there was no need to address the

relative merit of defendant’s arguments as to the violation of his right to confrontation, in

light of the absence of “any meaningful attempt by defendant to gain access to, or compel

disclosure of, the source code prior to trial” (175 AD3d at 173).

       A Judge of this Court granted defendant leave to appeal (35 NY3d 1097 [2020]) and

we now affirm.

                                            III.

                                           - 14 -
                                          - 15 -                                    No. 3

       We must address whether the trial court abused its discretion in determining that

TrueAllele “is not novel but instead is ‘generally accepted’ under the Frye standard” (47

Misc 3d at 859). Defendant argues that the evidence the People presented at the Frye

hearing was insufficient because, absent disclosure of the TrueAllele source code for

examination by the scientific community, its “proprietary black box technology” cannot be

generally accepted as a matter of law.9 He further asserts that, even if such technology

could be generally accepted, the People failed to meet their burden at the hearing, given

the dearth of independent validation as a result of Dr. Perlin’s involvement in the large

majority of studies produced at the hearing.

       The well-known Frye test applied to the admissibility of novel scientific evidence

(Frye v United States, 293 F 1013 [DC Cir 1923]) is “whether the accepted techniques,

when properly performed, generate results accepted as reliable within the scientific

community generally” (People v Wesley, 83 NY2d 417, 422 [1994]). General acceptance

by the relevant scientific community, however, does not require that the procedure be

“‘unanimously indorsed’” (83 NY2d at 423, quoting People v Middleton, 54 NY2d 42, 49

[1981]).

9
  Of note, the term “black box” is used in a federal report to describe subjective methods
inside an examiner’s head, the foundational validity of which must be established through
empirical studies of the examiner’s performance (see President’s Council of Advisors on
Sci. and Tech., Exec. Office of the President, Forensic Science in Criminal Courts:
Ensuring Scientific Validity of Feature-Comparison Methods, at 49 [2016]
https://obamawhitehouse.archives.gov/sites/default/files/microsites/ostp/PCAST/pcast_fo
rensic_science_report_final.pdf [published after the Frye hearing was held]).
                                          - 15 -
                                          - 16 -                                     No. 3

       At issue in Wesley was the general acceptance of DNA evidence—specifically, the

restriction fragment length polymorphism (RFLP) methodology, including the assessment

of a visual “match” between DNA samples. There, in a concurring opinion, Chief Judge

Kaye warned of the “pitfalls of self-validation by a small group” and urged caution in

accepting technology that has been validated by individuals with a commercial or

professional interest in promoting its use, “developed in commercial laboratories under

conditions of secrecy, preventing emergence of independent views” and had not been peer-

reviewed (83 NY2d at 439-440 [quotation marks and citations omitted]). Notwithstanding

these concerns, Chief Judge Kaye ultimately agreed that, at the time the appeal was

decided, “RFLP-based forensic analysis [was] generally accepted as reliable” and those

testing procedures were accepted as the standard methodology used in the scientific

community until the advent of the PCR STR method used today.

       Here, the evidence presented at the Frye hearing established that the relevant

scientific community generally accepted TrueAllele’s DNA interpretation process and that

the continuous probabilistic genotyping approach is more efficacious than human review

of the same data using the stochastic threshold. It was undisputed that the foundational

mathematical principles (MCMC and Bayes’ theorem) are widely accepted in the scientific

community. It was also undisputed that the relevant scientific community was fully

represented by those persons and agencies who weighed in on the approach. Although the

continuous probabilistic approach was not used in the majority of forensic crime

laboratories at the time of the hearing, the methodology has been generally accepted in the

                                          - 16 -
                                           - 17 -                                      No. 3

relevant scientific community based on the empirical evidence of its validity, as

demonstrated by multiple validation studies, including collaborative studies, peer-reviewed

publications in scientific journals and its use in other jurisdictions. The empirical studies

demonstrated TrueAllele’s reliability, by deriving reproducible and accurate results from

the interpretation of known DNA samples.

       Defendant and the concurrence raise the legitimate concern that the technology at

issue is proprietary and the developer of the software is involved in many of the validation

studies. This skepticism, however, must be tempered by the import of the empirical

evidence of reliability demonstrated here and the acceptance of the methodology by the

relevant scientific community. First, Dr. Perlin’s hearing testimony established that, in

forensic science, “most validation studies are internal and they’re not published,” but the

FBI’s Quality Assurance Standards requires that “a developmental validation for a

particular technology” be published (see also NIST, DNA Mixture Interpretation: A NIST

Scientific    Foundation      Review,      at       64   [June    2021      Draft     report]

https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8351-draft.pdf).     The interest of the

developer was addressed at the Frye hearing in this case and, contrary to defendant’s

argument, Dr. Perlin’s involvement in many of the validation studies does not preclude a

determination of general acceptance as a matter of law.10 The concurrence’s claim to the

10
   We recently held in People v Williams (35 NY3d 24) that the trial court abused its
discretion to deny a Frye hearing as to the admissibility of low copy number DNA evidence
and the use of the Forensic Statistical Tool (FST) to determine the likelihood ratio. That
case involved the use of proprietary “black box” technology for the FST, unique to the
New York City Office of Chief Medical Examiner, which was a “semi-continuous”
                                           - 17 -
                                           - 18 -                                     No. 3

contrary ignores that the performance of validation studies by Dr. Perlin, the State Lab and

independent agencies were entirely consistent with the scientific method (see e.g.

President’s Council of Advisors on Sci. and Tech., Exec. Office of the President, Forensic

Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods,

at                                        46                                         [2016]

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

rensic_science_report_final.pdf [published after the Frye hearing was held]). Here, unlike

in Wesley, there were developer and independent validation studies and laboratory internal

validation studies, many published and peer-reviewed. The technology was approved for

use by NIST and for forensic casework in New York by both the DNA Subcommittee and

the full CFS—entities that were established, in part, in response to the concerns raised in

Wesley as to the lack of independent scientific validation of DNA technology (Governor’s

Approval Mem, Bill Jacket, L 1994, ch 737; Executive Law § 995-b). Importantly, the

Lab, in accepting the True Allele Casework System after approval by the CFS, must still

conduct additional validation of the program and the hearing testimony indicates that they

did so in this case. In addition, NIST’s use of the TrueAllele system for its standard

probabilistic genotyping approach that used the concept of allelic dropout in analyzing
multiple source samples. The FST had not been subject to “unbiased” review by the
relevant scientific community and warranted the Frye scrutiny. In stark contrast, these
concerns were allayed in this case by the Frye evidence of the multiple validation studies
of the instrument through empirical evidence by multiple agencies and the uncontroverted
acceptability of the methodology in the relevant scientific community.

                                           - 18 -
                                           - 19 -                                      No. 3

reference materials likewise demonstrates confidence within the relevant community that

the system generates accurate results.11

       Disclosure of the TrueAllele source code was not needed in order to establish at the

Frye hearing the acceptance of the methodology by the relevant scientific community. 12

First, defendant’s initial attempt to obtain the source code was made by a July 2014

supplemental demand under the former demand-discovery provision (former CPL 240.20).

Defendant was not entitled to the source code under that provision, as the source code is

not a “written report or document” made at the People’s request for trial purposes and the

proprietary information belonging to Cybergenetics was not in the People’s possession or

control (see former CPL 240.20 [1] [c]; former CPL 240.45; People v Washington, 86

NY2d 189 [1995]; compare People v DaGata, 86 NY2d 40 [1995] [error to deny defendant

access to FBI notes relating to DNA testing not in the People’s possession]). As we have

11
  TrueAllele is not an outlier in the use of the continuous probabilistic genotyping method.
Other types of probabilistic genotyping software, such as STRMix, have likewise been
found to be generally accepted (see e.g. United States v Gissentaner, 990 F3d 457, 467 [6th
Cir 2021]).
12
   This conclusion is consistent with that reached by courts in several other jurisdictions
that have addressed these issues (see Commonwealth v Foley, 38 A3d 882 [PA Super 2012]
[TrueAllele evidence found admissible without a Frye hearing; rejected the argument that
Dr. Perlin’s methodology could not be verified absent disclosure of the source code];
People v Chubbs, 2015 WL 139069, at *9 [Cal Ct App Jan. 9, 2015] [defendant failed to
make “a prima facie showing of the particularized need for TrueAllele’s source code”];
State v Simmer, 304 Neb 369, 387 [Neb 2019] [district court was not “required to find that
TrueAllele had been validated ‘from a software engineering perspective’ to find it
reliable”]; compare State v Pickett, 246 A3d 279, 283-284 [NJ Super Ct App Div 2021]
[finding that the defendant was entitled to disclosure of the TrueAllele source code, subject
to a protective order, for the Frye hearing]).
                                           - 19 -
                                          - 20 -                                     No. 3

previously explained, the former article 240 of the CPL was “a detailed discovery regimen”

and “[i]tems not enumerated in article 240 [were] not discoverable as a matter of right

unless constitutionally or otherwise specially mandated” (People v Colavito, 87 NY2d 423,

427 [1996]). Outside of his discovery demand, defendant made no further attempt to

demonstrate a particularized need for the source code by motion to the court (see former

CPL 240.40 [1] [c]).

       Moreover, defendant’s arguments as to why the source code had to be disclosed pay

no heed to the empirical evidence in the validation studies of the reliability of the

instrument or to the general acceptance of the methodology in the scientific community—

the issue for the Frye hearing—and are directed more toward the foundational concern of

whether the source code performed accurately and as intended (see Wesley, 83 NY2d at

429). To the extent the testimony at the hearing reflected that the TrueAllele Casework

System may generate less reliable results when analyzing more complex mixtures (see also

President’s Council of Advisors on Sci. and Tech., Exec. Office of the President, Forensic

Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods,

at                                       80                                         [2016]

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

rensic_science_report_final.pdf [published after the Frye hearing was held]), defendant did

not refine his challenge to address the general acceptance of TrueAllele on such complex

mixtures or how that hypothesis would have been applicable to the particular facts of this

case. As a result, it is unclear that any such objection would have been relevant to

                                          - 20 -
                                           - 21 -                                      No. 3

defendant’s case, where the samples consisted largely of simple (two-contributor) mixtures

with the victim as a known contributor (see also NIST, DNA Mixture Interpretation: A

NIST     Scientific   Foundation     Review,      at   3   [June    2021    Draft    report]

https://nvlpubs.nist.gov/nistpubs/ir/2021/NIST.IR.8351-draft.pdf).

                                            IV.

       Defendant also argues that the source code for the software is the declarant and that,

in the absence of disclosure of the source code, he was deprived of his Sixth Amendment

right to confront the witness against him. He maintains that the TrueAllele system involves

artificial intelligence and, to some extent, draws its own inferences from the data. He

asserts that Dr. Perlin’s testimony was therefore that of a surrogate, merely parroting the

results of the analyst.

       Here, like the Lab reports on the generated DNA profiles, the report created by

TrueAllele providing the likelihood ratio that defendant was a contributor to the DNA

mixture profile found on the items of evidence is testimonial. The report was prepared by

Cybergenetics at the request of the People for purposes of prosecuting defendant in a

pending criminal proceeding. Indeed, the DNA results were sent to TrueAllele precisely

because of its “more advanced approach to analyzing the DNA evidence”—i.e., its

consideration of patterns and peaks below the stochastic threshold and ability to produce a

                                           - 21 -
                                            - 22 -                                      No. 3

higher match statistic. Therefore, the report satisfies our primary purpose test and was

testimonial (see People v John, 27 NY3d at 303-308).13

       However, we reject defendant’s novel argument that the source code is the

declarant. Even if the TrueAllele system is programmed to have some measure of

“artificial intelligence,” the source code is not an entity that can be cross-examined. “[T]he

Confrontation Clause provides two types of protections for a criminal defendant: the right

physically to face those who testify against him, and the right to conduct cross-

examination” (Coy v Iowa, 487 US 1012, 1017 [1988], quoting Pennsylvania v Ritchie,

480 US 39, 51 [1987] [plurality opinion]). The essential purpose of the provision was to

ensure “‘a personal examination and cross-examination of the witness, in which the

accused has an opportunity, not only of testing the recollection and sifting the conscience

of the witness, but of compelling him to stand face to face with the jury in order that they

may look at him, and judge by his demeanor upon the stand and the manner in which he

gives his testimony whether he is worthy of belief’” (California v Green, 399 US 149, 157-

158 [1970], quoting Mattox v United States, 156 US 237, 242-243 [1895]).

       In Bullcoming v New Mexico, the United States Supreme Court addressed an

argument that a laboratory report could be introduced into evidence through the testimony

of an analyst who did not personally perform or observe the test because the gas

13
   The source code, which was programmed long before defendant’s trial, is not in itself
testimonial. The source code is not a statement, was not “prepared in a manner resembling
ex parte examination” and does not accuse defendant of a crime (27 NY3d at 307 [quotation
marks and citations omitted]).
                                            - 22 -
                                            - 23 -                                     No. 3

chromatograph machine, used to analyze the blood alcohol content of the accused’s blood

sample, was the “true accuser” and the analyst who ran the test was a “mere scrivener”

(564 US 647, 659 [2011] [internal quotation marks omitted]). The Court did not expressly

address the concept that a machine can be a declarant, but rejected it sub silentio. Instead,

the Court focused on the actions taken by the analyst who operated the machine that would

be the appropriate subject of cross-examination—e.g., that the blood sample was received

in an intact condition, that a particular test was performed on the sample number that

corresponded to the case and that the test was performed according to protocol (see 564

US at 660). In other words, the analyst “certified to more than a machine-generated

number” (564 US at 661; see also John, 27 NY3d at 311 [declining to “indulge in the

science fiction that DNA evidence is merely machine-generated, a concept that reduces

DNA testing to an automated exercise requiring no skill set or application of expertise or

judgment”]).    Similarly, here, the instrument performs its quantitative analysis on

electronic data generated by the Lab during the electrophoresis process only after the

analyst sets the parameters following a human review of the data. And both the analyst

who performed the electrophoresis on the DNA samples and Dr. Perlin, who fully

understood the parameters and methodology of the TrueAllele software in its DNA

interpretation processes, testified at trial and were subject to cross-examination.

       We agree with the Appellate Division that defendant failed to preserve the separate

argument that he was entitled to disclosure of the source code in order to fully cross-

examine Dr. Perlin as the declarant at trial and, regardless, defendant’s argument suffers

                                            - 23 -
                                         - 24 -                                     No. 3

from the same defect as the request for the source code for purposes of the Frye hearing.

Defendant was not entitled to the source code under the former demand discovery statute.

After the People refused the demand, defendant failed to make any further attempt to

demonstrate a particularized need for the source code by motion to the court (see former

CPL 240.40 [1] [c]; CPL 245.30 [3]).

      Defendant’s remaining arguments, including the arguments raised in his pro se brief,

are without merit.

      Accordingly, the order of the Appellate Division should be affirmed.

                                         - 24 -
RIVERA, J. (concurring in result):

      Traditional DNA testing employs human analysis and judgment (see Erin Murphy,

The Art in the Science of DNA: A Layperson’s Guide to the Subjectivity Inherent in

Forensic DNA Typing, 58 Emory LJ 489, 501-508 [2008]). As a consequence, test results

                                        -1-
                                           -2-                                        No. 3

may reflect human error and bias, especially in cases involving mixtures of small amounts

of DNA from two or more individuals (see e.g. John M. Butler et al., NIST Interlaboratory

Studies Involving DNA Mixtures [MIX05 and MIX13]: Variation Observed and Lessons

Learned, 37 Forensic Scis Intl: Genetics 81 [2018]; Itiel E. Dror & Greg Hampikian,

Subjectivity and Bias in Forensic DNA Mixture Interpretation, 51 Sci & Just 204 [2011];

see also Saul M. Kassin et al., The Forensic Confirmation Bias: Problems, Perspectives,

and Proposed Solutions, 2 J Applied Rsch Memory & Cognition 42 [2013]). Enter

probabilistic genotyping software—here, a platform branded TrueAllele—a computer-

based form of DNA analysis dependent on complex mathematical models and artificial

intelligence to derive DNA profiles from complex, multi-person mixtures. While

TrueAllele does not completely replace humans, it comes pretty close by eliminating all

but the most rudimentary of human participation.

       At defendant’s trial, the court admitted DNA results developed using the TrueAllele

methodology, even though at the time its source code and underlying algorithms were kept

from independent evaluators and the defense as trade secrets. The court’s decision was an

abuse of discretion as a matter of law because it relied on validation studies by interested

parties and evaluations founded on incomplete information about TrueAllele’s computer-

based methodology. Without defense counsel and objective, expert third-party access to

and evaluation of the underlying algorithms and source code, the court could not conclude

that TrueAllele’s brand of probabilistic genotyping was generally accepted within the

forensic science community. However, I concur in the result and would affirm defendant’s

conviction because the evidence against him was overwhelming and the error, even when

                                           -2-
                                            -3-                                        No. 3

considered with the other alleged trial errors raised on this appeal, could not have resulted

in the guilty verdict.

                                             I.

                                             A.

       In 2014, prior to defendant’s trial for murder and robbery, the court held a Frye

hearing on the admissibility of the prosecutor’s DNA evidence developed by use of a

proprietary probabilistic genotyping methodology called TrueAllele. The prosecutor

sought to establish the likelihood that defendant committed the crimes with results based

on TrueAllele’s computerized interpretive analysis of mixtures of more than one

individual’s DNA. In preparation for the hearing, defendant requested but was denied

access to TrueAllele’s source code, which would have revealed the underlying algorithmic

assumptions that replace human judgment.

       The majority adequately describes the science-based, analytical challenges

presented by mixed DNA samples, like those in issue at defendant’s trial, and I do not

repeat them here (see majority op at 7-9). Instead, I focus on the testimonial description of

TrueAllele and the studies relied upon by the prosecution and referenced by the majority

to support its conclusion that, at the time of the Frye hearing, TrueAllele was generally

accepted within the relevant scientific community of forensic scientists.

       The most revealing and significant hearing testimony came from Dr. Mark Perlin,

M.D., Ph.D., the founder of Cybergenetics and the lead developer of TrueAllele. He

testified that TrueAllele Casework was first developed in 1999, after he had already

                                            -3-
                                              -4-                                          No. 3

developed and commercialized TrueAllele Databank, a DNA database software.1 Dr. Perlin

stated that TrueAllele is an “expert system,” defined as a “computer system that replicates

human expertise,” usually using artificial intelligence, that makes its own inferences.

TrueAllele uses a probabilistic genotyping model, which calculates the probabilities that

specific allele pairs belong to the genotype of a particular individual in a mixed, low-

template DNA sample. Put another way, TrueAllele sifts through scattered genes in a DNA

sample and attempts to reconstruct them into a potential genotype, picking from

algorithms, equations, and assumptions that can help it to reach a valid conclusion. The

core of TrueAllele is a Markov chain Monte Carlo (MCMC) algorithm, an often-used

statistical model first developed in the 1950s that determines the probabilities of all the

possible probabilities that explain a set of data.

         TrueAllele’s probabilistic genotyping model, according to Dr. Perlin, was

developed in the context of well-known flaws in the field of stochastic, or threshold,

modeling in DNA interpretation. Thus, TrueAllele was based on “a need to use normative

statistics and mathematical analysis that’s used in all other fields where you use all the

data, it’s examined objectively, you build and validate and test statistical models, use

computers and accept that reliable results . . . can be learned, taught and used.”

         Following the MCMC calculation, TrueAllele “reports out what the genotype is for

each contributor at each locus” by “looking at . . . the probabilities across all the allele pairs

at [a] locus for . . . one contributor without particular regard to any particular allele pair.”

1
    References to TrueAllele are to the Casework system, unless otherwise specified.
                                              -4-
                                             -5-                                          No. 3

TrueAllele also accounts for various variables and determines which of those variables to

apply in its analysis. Finally—and separately from its inferential processes—TrueAllele

compares the “inferred” genotypes against a random population to produce a likelihood

ratio based upon a known reference sample, using standard methods of DNA comparison.

       Dr. Perlin described an analyst’s process of using TrueAllele as follows. Initially,

raw data from a .FSA file, produced after an electropherogram is generated in a laboratory

from DNA samples, are imported into TrueAllele, at which point TrueAllele analyzes the

data “in order to determine the size and heights of the peaks to develop quantitative data.”

Then, an analyst asks the computer a question, such as “[a]ssuming that there are two

contributors, what are the genotypes of those two contributors.” In general, those questions

are preset for ease of use, but trained analysts have the option to ask more complex

questions and set additional parameters. After the analyst asks the computer questions, the

computer conducts the relevant calculations, drawing on its algorithm and programming to

help it determine which equations or models it should use. Generally, as part of the

question, the analyst will tell TrueAllele to run a particular number of MCMC calculations.

Dr. Perlin testified that the number of calculations can vary depending on the amount of

time and computer resources allocated to the case or whether TrueAllele is working with

an “easy mixture.” Using TrueAllele, “[t]he computer does the work, we don’t, we just set

up the variables. And the amount of computation is proportional to the number of variables

that you’re considering. So . . . if it’s thinking a lot harder then it’s going to take longer.”

The analyst also looks for concordance between genotypes across each run of the software

and can ask for additional MCMC calculations if necessary. Finally, the software

                                             -5-
                                             -6-                                         No. 3

“produces probabilities and then it writes them down.” Thereafter, an analyst can compare

the genotype(s) inferred by TrueAllele against known reference samples or DNA

databases.

        According to Dr. Perlin, unlike threshold DNA models, which exclude data from an

analyst’s review, TrueAllele is fully continuous, in that it uses “the peak height data and

the patterns of those peak rise[s].” In contrast, using a “threshold model,” a human analyst

“get[s] a fixed list of possible alleles, and then by looking at all pairwise combinations of

those alleles, those will be included genotypes.” Generally, an analyst will input “the alleles

or the putative alleles . . . into software by hand and then the computer calculates one over

the square of the frequencies of those alleles, the sum of it, and then produces a match

statistic.”

        In comparing TrueAllele to threshold methods of DNA analysis, Dr. Perlin

explained that “the computer can do it or the lab can do it. . . . [H]aving a better way of

understanding the data through statistical modeling and computer interpretation is a way

of looking at the data you have and extracting more information from it.” Computer

analysis can thus go beyond human review of a sample using methods and calculations that

a human would be unable to replicate. Essentially, this testimony revealed that TrueAllele

extrapolates and processes data to make judgments that supplant human choice, leading to

conclusions based on assumptions generated by artificial intelligence.

        Dr. Perlin asserted that TrueAllele had gone through 25 unique version numbers for

its software since 1999 and had 170,000 lines of source code, inclusive of “the user

                                             -6-
                                            -7-                                         No. 3

interface, the way it interacts with databases, [and] the way it solves problems.” 2

TrueAllele had last received a significant update in 2008, when Dr. Perlin and his team

“put in more hierarchical modeling to account for even more of the variation” in inferring

genotypes. Dr. Perlin testified that the development team “made no effort to preserve”

earlier versions of TrueAllele.

       TrueAllele underwent an initial validation study in the early 2000s. The software

was first used in a criminal trial in Pennsylvania in 2009, and was subsequently found

admissible in Virginia, California, Northern Ireland, and Australia. The New York State

Police Forensic Investigation Center (FIC) was in the process of onboarding TrueAllele,

and a state and international crime lab had both fully adopted TrueAllele for forensic work.

Seven other labs had also purchased the TrueAllele software package. The DNA

Subcommittee of the New York State Commission on Forensic Sciences and the full

Commission had approved TrueAllele for laboratory use. Likewise, the National Institute

of Standards and Technology (NIST) had used TrueAllele to verify one of its reference

2
   Dr. Perlin’s testimony reveals that TrueAllele does not comply with the SWGDAM
guidelines cited by the majority (see majority op at 8 n 5). Those guidelines require that
probabilistic genotyping software undergo new validation studies upon “significant”
software changes (SWGDAM Guidelines for the Validation of Probabilistic Genotyping
Systems                §            5.2             [2015],            available            at
https://www.swgdam.org/_files/ugd/4344b0_22776006b67c4a32a5ffc04fe3b56515.pdf
[last accessed Mar. 27, 2022]). To ensure that that requirement is met, the guidelines also
require that “[e]very software release should have a unique version number” (id. § 2.2.1).
It is clear from the record that Dr. Perlin has not preserved past versions of TrueAllele and
only one of his published validation studies (see infra n 3) identifies which version number
of TrueAllele was being tested. The majority also points out that FIC conducted internal
validation studies in line with 2010 SWGDAM guidelines (see majority op at 8 n 5). While
true, that fact is not relevant on this appeal because Cybergenetics, not FIC, analyzed the
DNA sample using TrueAllele.
                                            -7-
                                           -8-                                        No. 3

material kits. NIST had also hosted conferences and meetings to encourage laboratories to

adopt probabilistic genotyping models like TrueAllele.

       Dr. Perlin testified that TrueAllele had undergone approximately 25 validation

studies, resulting in several peer-reviewed publications and some prints that were pre-

publication at the time of the hearing. Seven of those peer-reviewed studies and two non-

peer-reviewed validation studies were entered into evidence.3 Dr. Perlin either conducted

or participated in all of these studies. He also explained that the source code was a “trade

secret,” but that the basic mathematical equations underlying TrueAllele were published in

the literature. However, “[t]he engineering of the elaboration of [the equations] in more

levels of hierarchy” were proprietary. Dr. Perlin argued that source code validation was

3
  The seven peer-reviewed studies were: Susan A. Greenspoon et al., Establishing the
Limits of TrueAllele Casework: A Validation Study, 60 J Forensic Scis 1263 (2015); Mark
W. Perlin et al., TrueAllele Genotype Identification on DNA Mixtures Containing Up to
Five Unknown Contributors, 60 J Forensic Scis 857 (2015); Mark W. Perlin et al.,
TrueAllele Casework on Virginia DNA Mixture Evidence: Computer and Manual
Interpretation in 72 Reported Criminal Cases, 9 PLoS ONE e92837 (2014); Mark W.
Perlin et al., New York State TrueAllele Casework Validation Study, 58 J Forensic Scis
1458 (2013); Jack Ballantyne et al., DNA Mixture Genotyping by Probabilistic Computer
Interpretation of Binomially-Sampled Laser Captured Cell Populations: Combining
Quantitative Data for Greater Identification Information, 53 Sci & Just 103 (2013); Mark
W. Perlin et al., Validating TrueAllele DNA Mixture Interpretation, 56 J Forensic Scis 1430
(2011); Mark W. Perlin & Alexander Sinelnikov, An Information Gap in DNA Evidence
Interpretation, 4 PLoS ONE e8327 (2009).

Several other articles on the field of probabilistic genotyping were also received into
evidence, including: Christopher D. Steele & David J. Balding, Statistical Evaluation of
Forensic DNA Profile Evidence, 1 Ann Rev Stat & Its Application 361 (2014); Hannah
Kelly et al., A Comparison of Statistical Models for the Analysis of Complex Forensic DNA
Profiles, 54 Sci & Just 66 (2014); Duncan Taylor et al., The Interpretation of Single Source
and Mixed DNA Profiles, 7 Forensic Sci Intl Genetics 516 (2013); James M. Curran, A
MCMC Method for Resolving Two Person Mixtures, 48 Sci & Just 168 (2008).
                                           -8-
                                             -9-                                        No. 3

“not needed” because, in his view, “[t]he question when conducting a validation study had

to do with the reliability of the system, the reliability of the software, not the text of the

code that underlies that reliable system.”

       Barry Duceman, Ph.D., who was then the Director of the Biological Section of FIC,

testified that he was in charge of implementing and validating TrueAllele’s Databank and

Casework systems and obtaining the State Forensic Commission’s approval for its use. Dr.

Duceman testified to TrueAllele’s “increased sensitivity” and “stronger statistical

measure,” meaning that TrueAllele can do what a human cannot or will not. He also

testified to the threshold approaches currently used in DNA testing, explaining that they

resulted in data being excluded from analysis. However, Dr. Duceman testified that his

laboratory had yet to use TrueAllele because they were still running further validation

studies.

       Jay Caponera, a Forensic Scientist 3 with FIC, testified that he had conducted

internal validation studies on TrueAllele for FIC. Caponera also discussed his training on

the use of TrueAllele and testified to attending conferences hosted by NIST on probabilistic

genotyping and the use of TrueAllele in other jurisdictions, as well as his review of the

scientific literature. Caponera did not have access to the source code.

       The court concluded that TrueAllele was generally accepted in the scientific

community, based largely on the validation studies and its use in some laboratories and

criminal cases in the United States and abroad (47 Misc 3d 850 [Sup Ct, Schenectady

County 2015]).

                                             -9-
                                           - 10 -                                     No. 3

                                            B.

       The victim was discovered in his home, facedown and propped against the couch.

His laptop and videogame console were missing. At trial, the prosecutor argued that

defendant strangled the victim and stole his property to sell for drugs. Undisputed evidence

established that the victim had died of asphyxia due to ligature strangulation from a guitar

cord, and that defendant and victim were known to each other and were together at the

victim’s home just before the estimated time of the murder.

       The prosecution presented testimonial and physical evidence of defendant’s guilt.

One witness testified that she knew defendant regularly bought drugs with money and by

trading property, and that a few months after the victim’s death, defendant, while at a

“crack house,” told her he had a laptop and videogame system to trade for drugs, and that

she saw him with a duffel bag which she identified as the same bag the victim was holding

in a photograph taken years prior. The prosecutor also presented evidence that the police

recovered the receipt for the videogame console, and a former employee from the maker

confirmed that the console went online five days after the victim’s death and that the IP

address for the console matched the address of a person who another witness identified as

a known drug dealer who had supplied one of the drug houses frequented by defendant.

       Three witnesses testified that defendant admitted to killing the victim. One witness

testified that he knew defendant for decades and that a few days after the murder, defendant

showed him a marijuana pipe which he said he took from a man “he had choked and took

out” with a guitar cord. The witness came forward to the police months later, after he heard

about the murder and a reward for information about the crime. The two other witnesses

                                           - 10 -
                                            - 11 -                                      No. 3

testified that defendant separately confessed to them when they were each incarcerated

with defendant. One of those witnesses testified that defendant admitted to going to the

victim’s apartment to steal his musical equipment and then killed him when things got out

of hand. The other witness testified that he had known defendant for years and that they

had smoked crack together. Defendant admitted to killing the victim and stealing his laptop,

gaming system, and other items, which he sold for drugs. Defendant also provided the

witness with details of his interaction with the victim the evening before the murder,

including the type of liquor they were drinking in the apartment and descriptions of the two

other people who were present. The court admitted evidence from the victim’s garbage of

a liquor bottle with defendant’s DNA on it which also matched the slang name of the liquor

mentioned by defendant. The two individuals who had been with defendant and the victim

the night before the victim was killed also testified to seeing defendant drinking alcohol at

the victim’s apartment.

       The prosecution’s additional conventional DNA analysis further inculpated

defendant. According to the results, neither defendant nor the victim could be excluded

from a sample obtained from the rear collar of the victim’s shirt containing a mixed profile,

with a combined probability of inclusion (CPI) of 1 in 1,088. A DNA sample obtained from

a swab taken from the victim’s right dorsal forearm was also found to have a CPI of 1 in

422 with regards to defendant and the victim.

       As further proof of defendant’s guilt, Dr. Perlin testified that, based on his analysis

using the TrueAllele methodology, it was 300 million times more probable that defendant

contributed to DNA obtained from the guitar cord than an unrelated African American

                                            - 11 -
                                           - 12 -                                      No. 3

person, one quintillion times more probable that defendant contributed to DNA obtained

from the back of decedent’s shirt collar than an unrelated African American person, 10

billion times more probable that defendant contributed to DNA obtained from the front of

decedent’s shirt collar than an unrelated African American person, and 56.1 million times

more probable that defendant contributed to DNA obtained from a swab of the cut on

decedent’s forearm than an unrelated African American person.

       Defendant argued that he was entitled to TrueAllele’s source code at trial in order

to challenge the DNA evidence pursuant to his Sixth Amendment right to confrontation.

The court denied the request, concluding that the source code was neither a witness nor

testimonial in nature under the Confrontation Clause.

       The jury convicted defendant of one count each of first-degree murder and robbery,

and the court sentenced him to life imprisonment without parole. The Appellate Division

affirmed the judgment of conviction (175 AD3d 158 [3d Dept 2019]). A Judge of this Court

granted defendant leave to appeal (35 NY3d 1097 [2020]). I would affirm, but not for the

reasons set forth in the majority analysis. Here, the court erred in admitting the TrueAllele

results but the error, either alone or considered with defendant’s claims of other alleged

errors, was harmless.

                                             II.

       “The admissibility and scope of expert testimony are subject to the discretion of the

trial court, limiting our scope of review to whether the determination to exclude the

proffered expert testimony was an abuse of that discretion as a matter of law” (People v

Powell, 37 NY3d 476, 489 [2021] [citation omitted], citing People v Lee, 96 NY2d 157,

                                           - 12 -
                                            - 13 -                                       No. 3

162 [2001]). New York courts follow the approach set out in Frye v United States (293 F

1013 [DC 1923]), which asks “whether the accepted techniques, when properly performed,

generate results accepted as reliable within the scientific community generally” (People v

Wesley, 83 NY2d 417, 422 [1994]). “In determining whether . . . DNA profiling evidence

[is] properly admissible, attention must focus on the acceptance of such evidence as reliable

by the relevant scientific community” (id.). Under Frye, there must be “consensus[,]

[which] . . . has been described as ‘a surrogate for determining the reliability of a purported

scientific methodology’” (People v Williams, 35 NY3d 24, 37 [2020], quoting Michael M.

Martin et al., New York Evidence Handbook § 7.2.3 at 644 [1997]).

       “[T]he particular procedure need not be ‘unanimously indorsed’ by the scientific

community but must be ‘generally accept[ed] as reliable’” (Wesley, 83 NY2d at 423,

quoting People v Middleton, 54 NY2d 42, 49 [1981]). However, “[a] showing that an

expert’s opinion has ‘some support’ is not sufficient to establish general acceptance in the

relevant scientific community” (Williams, 35 NY3d at 37, quoting Cornell v 360 W. 51st

St. Realty, LLC, 22 NY3d 762, 783 [2014]). A novel method “should be supported by those

with no professional interest in its acceptance” because “Frye demands an objective,

unbiased review” (id. at 42). Indeed, “a proprietary program exclusively developed and

controlled by” one individual “is not ‘an appropriate substitute for the thoughtful exchange

of ideas . . . envisioned by Frye.’ It is an invitation to bias” (id. at 41, quoting Wesley, 83

NY2d at 441 [Kaye, Ch. J., concurring]).

       Defendant is correct that TrueAllele’s proprietary algorithm was not generally

accepted because its source code had not been tested and assessed as reliable by

                                            - 13 -
                                            - 14 -                                       No. 3

independent third parties within the relevant forensic scientific community.4 Although Dr.

Perlin has since offered to release the source code in other criminal proceedings, at the time

of the Frye hearing here he asserted that TrueAllele’s source code was a trade secret and

refused to turn it over to defendant (see e.g. State v Simmer, 304 Neb 369, 380, 935 NW2d

167, 177 [2019] [noting that “Cybergenetics had recently decided to allow defense experts

access to the TrueAllele source code, with limitations”]; State v Baugh, 2019 Ga Super

LEXIS 418, *18 [Apr. 29, 2019, No. 2017-CR-618, Palmer, J.] [“Dr. Perlin explained that

approximately two years ago he agreed to disclose TrueAllele’s source code under specific

conditions”]; but see United States v Ellis, 2021 US Dist LEXIS 36176, *1 [WD Pa, Feb.

26, 2021, No. 19-369, Ambrose, J.] [“Cybergenetics was not willing to disclose the source

code”], reconsideration denied 2021 WL 1600711, 2021 US Dist LEXIS 78212 [Apr. 23,

4
  It is a close question whether, at the time of the Frye hearing, probabilistic genotyping
was generally accepted as reliable for the DNA purposes for which it was used in
defendant’s prosecution (see e.g. Kelly et al. at 69 [“(T)he continuous model is unfamiliar
to many forensic DNA scientists”]; Taylor et al. at 517 [“(P)rogress is still partial with only
a few laboratories worldwide implementing or investigating fully continuous methods”
(endnote omitted)], citing Bruce Budowle et al, Mixture Interpretation: Defining the
Relevant Features for Guidelines for the Assessment of Mixed DNA Profiles in Forensic
Casework, 54 J Forensic Scis 810 [2009]). Indeed, the evidence and testimony at the Frye
hearing demonstrated that NIST and other forensic organizations sought to encourage the
use of probabilistic genotyping in an effort to overcome hesitance about this type of DNA
technology among forensic experts (see e.g. Gill et al. at 680 [“Clearly the adoption of
probabilistic models has been inhibited by the complexity of concepts that are largely
outside the experience of case-working forensic scientists, coupled with lack of suitable
training opportunities”]; Michael D. Coble & John M. Butler, NIST, Exploring the
Capabilities of Mixture Interpretation Using True Allele Software, Presentation at the 24th
Congress of the International Society for Forensic Genetics [Sept. 3, 2011], slides available
at https://strbase.nist.gov/pub_pres/ISFG2011-Coble-TrueAllele.pdf). Assuming it was
not an abuse of discretion for the court to decide as a threshold matter that this type of
analysis was generally accepted, for the reasons I discuss, the evidence is not at all close
as regards TrueAllele.
                                            - 14 -
                                            - 15 -                                       No. 3

2021]). Because there was no opportunity for members of the relevant scientific

community to review the source code, and specific software using a complex algorithm

cannot be deemed reliable in the scientific community without an independent review of

how the software reaches its conclusions—including the inferences made by artificial

intelligence—the prosecution failed to satisfy its burden at the Frye hearing. As the

President’s Council of Advisors on Science and Technology (PCAST) has made clear,

while “probabilistic genotyping software programs clearly represent a major improvement

over purely subjective interpretation[,] . . . they still require careful scrutiny to determine

. . . whether the software correctly implements the methods” (PCAST, Report to the

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

Comparison             Methods            79           [2016],           available           at

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

rensic_science_report_final.pdf [hereinafter PCAST Report];5 see also State v Pickett, 466

NJ Super 270, 305-306, 246 A3d 279, 301 [2021] [“Allowing independent access to the

requested information, for the sole purpose of addressing whether the technology

5
 It is unclear what significance the majority assigns to the PCAST Report’s use of the term
“black box” to refer to “subjective methods inside an examiner’s head” (majority op at 15
n 9). As the majority recognizes—other commenters and the courts routinely use “black
box” to refer to technologies with unknown internal workings (see id. at 17 n 10; Williams,
35 NY3d at 33-34; Katherine Kwong, Note, The Algorithm Says You Did It: The Use of
Black Box Algorithms to Analyze Complex DNA Evidence, 31 Harv JL & Tech 275, 292-
295 [2017] [discussing TrueAllele’s black box algorithm and transparency concerns]).
And, in common usage, “black box” refers to “a usually complicated electronic device
whose internal mechanism is usually hidden from or mysterious to the user” (see Merriam-
Webster         Online       Dictionary,       black        box    [https://www.merriam-
webster.com/dictionary/black%20box]). The majority merely engages in a rhetorical
comparison of the “black box” as object to the “black box” as an examiner’s mind.
                                            - 15 -
                                             - 16 -                                       No. 3

underlying the expert testimony is reliable—specifically, whether the source code for that

technology is properly implementing the program’s design specifications—is obvious”]).6

Just as a machine may need to be recalibrated and tested regularly for accuracy, the Frye

hearing evidence failed to establish that TrueAllele is generally accepted within the

forensic scientific community based on its inferential assumptions and its applications of

general mathematical principles.

       To be sure, Dr. Perlin had published the general mathematical principles behind

TrueAllele in the scientific literature at the time of the hearing. But those general principles

alone could not serve to validate TrueAllele’s unique, proprietary application and

inferences that are the basis for its ultimate DNA matching determinations. As Dr. Perlin

testified, TrueAllele goes beyond human capabilities in conducting calculations that would

be nearly impossible to do by hand; it also substitutes for humans in that it chooses which

of its models, algorithms, and equations to run based on the questions posed by human

analysts. So while the mathematical principles—such as MCMC—may be commonly

accepted and understood, the inferences and interpretive efforts made by TrueAllele that

are subject to challenge were unknown and unknowable at the time of the hearing because

6
  The majority suggests, without citation or support, that “simple (two-contributor)
mixtures with the victim as a known contributor” (majority op at 21) should be
distinguished from other DNA mixtures. This misses the mark because although a mixture
of several contributors apart from the victim may provide additional complicating factors,
the core problem is that the DNA is combined in the sample, requiring an analysis of the
data by means of justifiable assumptions and choices that accord with a methodology and
lead to a likelihood ratio that a particular individual is a contributor to the mixture. As Dr.
Perlin explained at the Frye hearing, describing a mixture as simple or complex largely
pertains to the ability of a human analyst “to obtain a reportable result using the methods
that they had” (see also Kelly et al. at 66).
                                             - 16 -
                                             - 17 -                                        No. 3

of Dr. Perlin’s refusal to turn over the source code. In effect, disclosure of the formulas,

but not the source code, is analogous to a student pointing to the correct equation to use

and giving an answer on a mathematics exam, without showing their work. In that case,

however, the teacher knows the correct answer to the exam question, notwithstanding

whether the student reached the answer incorrectly; here, there is no “generally accepted”

correct answer—as a scientific matter—unless the relevant scientific community can

determine that TrueAllele was making appropriate choices when doing the math. Put

another way, general principles cannot displace the need for an independent source code

review of software that makes its own decisions and inferences and where one error in a

decimal place or a missing parenthesis, or a choice to assume the existence of an allele

based on the computer’s judgment of an acceptable probability, can mean the difference

between inclusion and exclusion of a person as a DNA donor. Therefore, the court abused

its discretion as a matter of law by admitting the results of the TrueAllele’s analysis at trial.

       The majority’s view that the Frye hearing record established acceptance within the

scientific community is based on an overly favorable but unsupported view of the

testimony and documentary evidence. First, contrary to the majority’s suggestion, there is

no meaningful involvement by the analyst (see majority op at 7-8, 14). Dr. Perlin testified

that TrueAllele “does the work, we don’t” and that it relies on its programming to determine

the particular analytical tools that are appropriate based upon the data entered into the

system. That means there is all the more reason to provide defendant with access to the

source code—the algorithm makes the critical decisions and a human being is an “analyst”

in name only, as they merely provide the data that TrueAllele computes and probes. Indeed,

                                             - 17 -
                                           - 18 -                                      No. 3

this is TrueAllele’s defining service (see Kwong at 283 [“Dr. Perlin published an article

that called the interpretation method used by most laboratories a ‘random generator’ and

argues in interviews that his company's technology produces better probability

measurements” (footnote omitted)]).

       Second, the majority places undue reliance on evaluations by regulatory entities that

had only partial information; the widely accepted nature of TrueAllele’s underlying

mathematical principles; validation studies in which Dr. Perlin was conflicted due to his

financial interest in TrueAllele; and the perceived efficacy of probabilistic genotyping (see

majority op at 16-18). We have previously rejected or been skeptical of each of these types

of “supporting evidence.” In Williams, we made clear that “insular endorsement[s]” by

executive branch agencies—here, the DNA Subcommittee of the New York State Forensic

Science Committee and NIST—cannot “supplant the courts’ obligation to ensure” that a

scientific technique has gained general acceptance within the scientific community (35

NY3d at 41). Notably, the reliance on these agencies by the majority—and a description of

them as “the relevant scientific community” for the purposes of the Frye hearing (majority

op at 8)—is a jarring turnabout for the Court, given that it is the same view unsuccessfully

advocated by a minority in Williams two years ago (see Williams, 34 NY3d at 49-50 and n

1 [DiFiore, Ch. J., concurring]). That is particularly true in this appeal because Dr. Perlin

criticized the PCAST Report, arguing that “NIST lacks expertise in modern statistical

analysis”—which would presumably be a prerequisite to being a part of the relevant

scientific community that is qualified to evaluate (Letter from Dr. Mark Perlin, Chief

Scientific and Executive Officer, Cybergenetics, to Dr. John Holdren, Co-Chair, PCAST,

                                           - 18 -
                                           - 19 -                                     No. 3

at          3          [Sept.           16,          2016],           available           at

https://www.cybgen.com/information/newsroom/2016/sep/files/letter.pdf; see Kwong at

289).

        The majority—going further—also refers to the American National Standards

Institute (ANSI) as being part of the relevant scientific community (see majority op at 8-

9). ANSI, however, is a standards-development organization (SDO), a private industry

group that writes “voluntary consensus standards” for use in technological applications

(see Am. Socy. for Testing & Materials v Public.Resource.Org, Inc., 896 F3d 437, 440-441

[DC Cir 2018] [discussing role of SDOs in promulgating standards]; Robert W. Hamilton,

The Role of Nongovernmental Standards in the Development of Mandatory Federal

Standards Affecting Safety or Health, 56 Tex L Rev 1329, 1341-1368 [1978] [discussing

ANSI’s history and its procedures for developing industry standards]; see generally Harm

Schepel, The Constitution of Private Governance: Product Standards in the Regulation of

Integrating Markets 145–52 [2005] [discussing the history of SDOs in the United States]).

Including such organizations within the “relevant scientific community,” as the majority

does, raises similar concerns about professional interest and profit motive analogous to Dr.

Perlin’s involvement in the validation studies here (see infra at 20-21). Indeed, Dr. Perlin

was on a DNA working group that assisted in the development of a NIST standard

approved by ANSI that recognized probabilistic genotyping “as a valid approach to DNA

interpretation and reporting” (Perlin et al., New York State TrueAllele Casework Validation

Study at 1458, citing NIST Special Publication 500–290, ANSI/NIST-ITL 1-2011,

American National Standard for Information Systems: Data Format for the Interchange of

                                           - 19 -
                                           - 20 -                                      No. 3

Fingerprint, Facial & Other Biometric Information [July 2012], available at

https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=910136).

       In any case, without the source code, the agencies could not adequately evaluate the

use of TrueAllele for this type of DNA mixture analysis, and Dr. Perlin’s self-serving

statements to the contrary were insufficient to satisfy the prosecution’s burden. Williams

also rejected the notion that the use of known mathematical principles could satisfy the

Frye standard, explaining that such reasoning cannot overcome “the proprietary nature of

the [software] or the relatively narrow subsection of the relevant scientific community able

to examine and endorse that tool” (Williams, 34 NY3d at 42).

       Third, as for the validation studies, the majority acknowledges that Dr. Perlin

conducted or was involved in the majority of them. Given Dr. Perlin’s “professional

interest in [TrueAllele’s] acceptance” (id.), the studies must be viewed with a healthy dose

of skepticism and cannot support a conclusion of general acceptance. The majority attempts

to minimize this obvious conflict of interest with an unsupported statement that internal

validation studies and validation studies conducted by laboratories using the software is

“entirely consistent with the scientific method” and because Dr. Perlin’s interest was raised

at the hearing (majority op at 18).7 Contrary to the majority’s view, such conflicts do

present serious concerns about the integrity of the studies (see Wesley, 83 NY2d at 441

[Kaye, Ch. J., concurring]). As the literature shows, conflicts have long been a source of

concern within the scientific community and the standard procedure is to disclose such

7
  The majority recognizes that unpublished internal validation studies alone would be
insufficient to meet the Frye standard (see majority op at 17 and n 10).
                                           - 20 -
                                            - 21 -                                       No. 3

financial interests, not to assume, as the majority does, that they have little impact on the

study itself (see e.g. Singapore Statement on Research Integrity, World Conferences on

Research Integrity [2010], https://wcrif.org/statement; Sheldon Krimsky & L.S.

Rothenberg, Financial Interest and Its Disclosure in Scientific Publications, 280 JAMA

225 [1998]; Jerome P. Kassirer & Marcia Angell, Financial Conflicts of Interest in

Biomedical Research, 329 New Eng J Med 570 [1993]). Put another way, mere disclosure

of a conflict of interest and subsequent peer review cannot overcome the potential for bias.

Dr. Perlin’s professional interest in a favorable assessment of TrueAllele was raised at the

hearing, but its significance was discounted, and the validation studies were treated as if

conducted by disinterested third parties, confirming, rather than refuting, the court’s abuse

of its discretion. The remaining two validation studies not involving Dr. Perlin are similarly

of little value because they were conducted by the New York State Police FIS, which

presented a different form of conflict, as they had already invested significant time and

money in adopting TrueAllele for internal use.

       Additionally, the majority is incorrect that peer review and publication in a scientific

journal implies that “the empirical evidence of the reliability of TrueAllele was not

disputed” (majority op at 9). Peer review, while a prerequisite for publication, does not

imply that the relevant scientific community has generally accepted a scientific method as

reliable. Indeed, as the United States Supreme Court explained in Daubert v Merrell Dow

Pharmaceuticals, Inc.:

              “Publication (which is but one element of peer review) is not a
              sine qua non of admissibility; it does not necessarily correlate
              with reliability, and in some instances well-grounded but

                                            - 21 -
                                              - 22 -                                   No. 3

                innovative theories will not have been published. Some
                propositions, moreover, are too particular, too new, or of too
                limited interest to be published. But submission to the scrutiny
                of the scientific community is a component of “good science,”
                in part because it increases the likelihood that substantive flaws
                in methodology will be detected. The fact of publication (or
                lack thereof) in a peer reviewed journal thus will be a relevant,
                though not dispositive, consideration in assessing the scientific
                validity of a particular technique or methodology on which an
                opinion is premised” (509 US 579, 593-594 [1993]; see e.g.
                David H. Kaye et al., The New Wigmore: Expert Evidence §
                8.3.2 [b] [2] [“(P)eer review merely signifies that an article has
                been subject to some basic scrutiny for methodological and
                logical flaws. In even the best journals, that scrutiny sometimes
                is inadequate, and peer review is neither a necessary nor a
                sufficient condition for demonstrating the validity of a theory
                or technique” (footnotes omitted)]).
Thus, while peer review might be an appropriate factor for consideration under the federal

Daubert standard, it is insufficient under Frye (cf. Powell, 37 NY3d at 514 [Rivera, J.,

dissenting]).

       In sum, the majority is incorrect that “[i]t was . . . undisputed that the relevant

scientific community was fully represented by those persons and agencies who weighed in

on the [TrueAllele] approach” (majority op at 16). The prosecution’s case at the Frye

hearing turned on Dr. Perlin’s validation studies, the opinions of executive agencies and

private entities, and the mere fact of peer-reviewed publication, none of which are adequate

for the reasons I have discussed.

       We are left, then, only with the majority’s statement that probabilistic genotyping is

more efficacious than other DNA typing. That reasoning is circular because the point of

accessing the source code is to evaluate the programming and algorithm and to test the very

conclusion that TrueAllele is able to provide a reliable assessment of whether and in what

                                              - 22 -
                                            - 23 -                                       No. 3

ratio an individual’s DNA is likely found in DNA mixtures from a crime scene. On this

point, the court below and the majority make the same mistake—assuming that if the

system appears reliable then we need not know how the system reached its conclusions

(see id. at 16-17 [“The empirical studies demonstrated TrueAllele’s reliability, by deriving

reproducible and accurate results from the interpretation of known DNA samples”]). That

is contrary to the basic scientific method, which explores not only the end result but the

how and the why of an outcome, or “whether the source code performed accurately and as

intended” (id. at 20). That is no less true in forensic science where, as Dr. Perlin testified,

human choice can be based on bias and error. In order to ensure that TrueAllele—created

by a human—does not replace one form of bias or flawed assumption with another, third-

party independent reviewers must be provided with the source code. As the District

Attorney explains, “[t]he development of the computer inferred probability that an allele is

present at a specific locus is the major difference between TrueAllele and a human analyst.”

That difference is critical to results that either include or exclude an individual as a DNA

mixture contributor. Although a human analyst can be asked why they decided a peak was

or was not present, or why they believed they could not make a reliable determination of

the existence of a peak based on the available data, TrueAllele uses statistical modeling to

“infer[] the probability that the peak is present.” Without the source code, no independent

third party or defendant could challenge TrueAllele’s assumptions for what is essentially a

mathematical guess—a computer-run, theoretically-based conclusion, but still a guess.

                                            - 23 -
                                            - 24 -                                      No. 3

                                             III.

       Defendant further argues that the trial court’s denial of his request for the source

code so that an expert could review it was a violation of his constitutional right to

confrontation. The Sixth Amendment Confrontation Clause provides that, “‘[i]n all

criminal prosecutions, the accused shall enjoy the right . . . to be confronted with the

witnesses against [them]’” (Crawford v Washington, 541 US 36, 42 [2004]). “[T]he

principal evil at which the Confrontation Clause was directed was the civil-law mode of

criminal procedure, and particularly its use of ex parte examinations as evidence against

the accused” (id. at 50). Thus, although “the Clause’s ultimate goal is to ensure reliability

of evidence, . . . it is a procedural rather than a substantive guarantee. It commands, not

that evidence be reliable, but that reliability be assessed in a particular manner: by testing

in the crucible of cross-examination” (id. at 61). “The upshot is that the role of the trial

judge is not, for Confrontation Clause purposes, to weigh the reliability or credibility of

testimonial hearsay evidence; it is to ensure that the Constitution’s procedures for testing

the reliability of that evidence are followed” (Hemphill v New York, 595 US —, —, 142 S

Ct 681, 692 [2022]).

       “Therefore, ‘[a]s a rule, if an out-of-court statement is testimonial in nature, it may

not be introduced against the accused at trial unless the witness who made the statement is

unavailable and the accused has had a prior opportunity to confront that witness’” (People

v John, 27 NY3d 294, 303 [2016], quoting Bullcoming v New Mexico, 546 US 647, 657

[2011]). Under Crawford’s “primary purpose test for determining whether evidence is

testimonial,” this Court has “considered ‘whether the statement was prepared in a manner

                                            - 24 -
                                            - 25 -                                       No. 3

resembling ex parte examination and . . . whether the statement accuses defendant of

criminal wrongdoing’” (People v Austin, 30 NY3d 98, 104 [2017], quoting People v

Pealer, 20 NY3d 447, 453 [2013]). “Statements that are considered testimonial include

‘affidavits, . . . similar pretrial statements that declarants would reasonably expect to be

used prosecutorially . . . [and] statements that were made under circumstances which would

lead an objective witness reasonably to believe that the statement would be available for

use at a later trial’” (John, 27 NY3d at 303, quoting Crawford, 541 US at 51-52).

       The DNA evidence was clearly testimonial and subject to the Confrontation Clause.

Forensic reports are testimonial in nature because they are “‘functionally identical to live,

in-court testimony’ and . . . their ‘sole purpose’ [is] evidentiary in nature” (id. at 303-304,

quoting Melendez-Diaz v Massachusetts, 557 US 305, 310-311 [2009]). Further, it is

undisputed that defendant did not have access to the source code, and thus no way to

identify and challenge the underlying inferences drawn by TrueAllele and the application

of those inferences to the DNA. Defendant could not mount a viable challenge to the

conclusions based on the application of TrueAllele’s algorithm that linked him to the

murder.

       Defendant was entitled to cross-examine those who testified about the “sources” of

TrueAllele’s inferences—i.e., its source code—and “how [it] evaluated those sources in

arriving at [its] conclusion” (People v Stone, 35 NY2d 69, 76 [1974]). Dr. Perlin was a

declarant, but defendant could only effectively cross-examine him on his programming

assumptions, and any potential biases reflected therein, by reviewing the source code.

Although a computer cannot be cross-examined, as Dr. Perlin explained, the computer does

                                            - 25 -
                                           - 26 -                                      No. 3

the work, not the humans, and TrueAllele’s artificial intelligence provided “testimonial”

statements against defendant as surely as any human on the stand. Defendant makes a

compelling argument that he was entitled to challenge TrueAllele’s inferences and choices

that led to the DNA interpretations connecting him to the crime in the only way possible:

by access to the source code and questioning those who served as the human translators of

TrueAllele.

       The use of artificial intelligence within our system of justice presents challenging

questions and may destabilize our established notions of the dividing line between opinion

and uncontestable fact (see e.g. Sonia K. Katyal, Private Accountability in the Age of

Artificial Intelligence, 66 UCLA L Rev 54, 62-82 [2019]; Andrea Roth, Machine

Testimony, 126 Yale LJ 1972, 2021-2022 [2017]). Courts across the country will decide

how our federal and state constitutions may be interpreted in light of continued

technological advances and their application in the courtroom. For now, although the

questions presented are intellectually challenging and the answers will significantly impact

defendants’ rights, I need not resolve thorny esoteric questions in this appeal, nor the more

specific question of whether defendant was entitled to the source code under the

Confrontation Clause or another constitutional guarantee. As I discuss below, even

assuming defendant is correct, any constitutional error or abuse of discretion related to the

admission of the TrueAllele results without defendant’s access to the source code was

harmless.

                                           - 26 -
                                            - 27 -                                      No. 3

                                             IV.

       An error of constitutional dimension is “harmless beyond a reasonable doubt” when

“the proof of the defendant’s guilt, without reference to the error, is overwhelming,” and

there is “no reasonable possibility that the error might have contributed to defendant’s

conviction” (People v Crimmins, 36 NY2d 230, 237, 241 [1975]; see People v Perez, 36

NY3d 1093, 1093-1094 [2021]). Overwhelming proof exists where “the quantum and

nature of proof, excising the error, are so logically compelling and therefore forceful in the

particular case as to lead the appellate court to the conclusion that ‘a jury composed of

honest, well-intentioned, and reasonable [people]’ on consideration of such evidence

would almost certainly have convicted the defendant” (Crimmins, 36 NY3d at 241-242).

       Here, the totality of the evidence presented at trial, excluding the erroneously

admitted TrueAllele DNA evidence, was overwhelming proof of defendant’s guilt. There

was unchallenged DNA evidence obtained using traditional methods that linked defendant

to the crime, with combined probabilities of inclusion—for both decedent and defendant—

of 1 in 1,088 for the DNA obtained from decedent’s shirt collar, and 1 in 422 for the DNA

obtained from decedent’s right dorsal forearm. Defendant also did not contest that he had

been in decedent’s apartment. Moreover, three individuals testified that defendant made

inculpatory statements with similar details to each of them about stealing from and killing

decedent. Although defendant asserts that those witnesses were unreliable, and that the

“jailhouse” witnesses in particular had motive to lie, trial counsel successfully brought

those matters to the attention of the jury. Given this evidence, there is “no reasonable

possibility” that a jury would have acquitted defendant (id. at 237, 241-242). Thus, because

                                            - 27 -
                                            - 28 -                                     No. 3

the error was harmless under the more demanding constitutional standard, defendant is not

entitled to a new trial (cf. id. at 242 [explaining that an error is harmless under the

nonconstitutional standard when “there is a significant probability, rather than only a

rational possibility, in the particular case that the jury would have acquitted the defendant

had it not been for the error or errors which occurred”]; People v Easley, — NY3d —, —,

slip op at 6 [2022, Rivera, J., dissenting] [decided today] [explaining that admission of FST

DNA results was not harmless under non-constitutional standard because “(t)here was no

eyewitness who saw defendant in possession of the gun, no admission of his guilt, and no

video recording depicting him holding the gun at any time”]).8

                                              V.

         The order of the Appellate Division should be affirmed. Although the prosecutor

failed to establish that, at the time of the Frye hearing, TrueAllele’s methodology was

properly validated by disinterested parties with access to the source code, and defendant

was denied an opportunity to review the source code because of the developer’s proprietary

claims, the error, considered alone or with the other alleged constitutional error, was

harmless on the facts of this case.

         Even though the majority rejects defendant’s claim to the source code on the facts

of this case, it remains an open question in this Court whether a defendant should be granted

access to a proprietary source code under a protective order. This familiar method of

ensuring a defendant’s right to present a defense would safeguard commercial interests. It

8
    Defendant’s other challenges are either unpreserved or lack merit.
                                            - 28 -
                                            - 29 -                                       No. 3

provides no help to this defendant, but it is squarely within a court’s authority to grant such

an order in an appropriate future case.

Order affirmed. Opinion by Chief Judge DiFiore. Judges Garcia, Singas and Cannataro
concur. Judge Rivera concurs in result in an opinion, in which Judges Wilson and
Troutman concur.

Decided April 26, 2022

                                            - 29 -