                                 In the

       United States Court of Appeals
                   For the Seventh Circuit
                       ____________________

No. 18-2670
UNITED STATES OF AMERICA,
                                                     Plaintiff-Appellee,

                                   v.

MYSHAWN BONDS,
                                                 Defendant-Appellant.
                       ____________________

           Appeal from the United States District Court for the
             Northern District of Illinois, Eastern Division.
                 No. 15 CR 573 — Sara L. Ellis, Judge.
                       ____________________

        ARGUED APRIL 16, 2019 — DECIDED APRIL 24, 2019
                   ____________________

      Before EASTERBROOK, KANNE, and SCUDDER, Circuit Judg-
es.
    EASTERBROOK, Circuit Judge. A jury convicted Myshawn
Bonds of bank robbery, 18 U.S.C. §2113(a), and a judge sen-
tenced him to sixty months’ imprisonment plus three years’
supervised release. The evidence against him included the
testimony of Kira Glass, a ﬁngerprint examiner in the FBI’s
Latent Print Operations Unit. Glass concluded that Bonds’s
2                                                 No. 18-2670

ﬁngerprints appeared on the demand notes used in the two
robberies.
    In 2004 the Latent Print Operations Unit incorrectly iden-
tiﬁed Brandon Mayﬁeld as a person whose ﬁngerprints sug-
gested involvement in a terrorist bombing in Spain. Mayﬁeld
was arrested and held for more than two weeks as a material
witness, until the FBI acknowledged that its assessment re-
sulted from operational errors. The United States released
Mayﬁeld, apologized, and paid him substantial compensa-
tion. Bonds wanted to use this episode to illustrate for the
jury the potential for mistakes in the application of a method
that ﬁngerprint analysts dub ACE-V, for analysis, compari-
son, evaluation, and veriﬁcation. That method miscarried for
Mayﬁeld, and Bonds contended that it could miscarry for
him too.
    But the district judge concluded that evidence about
Mayﬁeld’s arrest in 2004 would take the trial far aﬁeld from
the question whether Bonds robbed two banks in 2015. The
judge permifed Bonds to cross-examine Glass about the re-
liability of the ACE-V method and to present other evidence
suggesting that the approach is more error-prone than jurors
are likely to believe after watching forensic labs operate to
perfection on television. Evidence about one particular error,
the judge concluded, would be more distracting and time
consuming than its incremental value could justify.
    Bonds contends that the district court’s decision to ex-
clude evidence about Mayﬁeld’s mistaken identiﬁcation and
arrest violated the Confrontation Clause of the Constitu-
tion’s Sixth Amendment. United States v. Rivas, 831 F.3d 931
(7th Cir. 2016), rejected an identical contention, holding that
a district court did not violate the Constitution when exclud-
No. 18-2670                                                  3

ing evidence about the Mayﬁeld situation. Bonds asks us to
distinguish Rivas on the ground that Glass works in the same
FBI division that mistakenly identiﬁed Mayﬁeld, but Bonds
does not contend that Glass was involved in that error. Guilt
by association would be a poor reason to deny a district
judge the discretion otherwise available under Fed. R. Evid.
403.
   Defense counsel suggested at oral argument that jurors
respond more strongly to concrete examples than to data
about error rates. That may well be true—but it is a reason to
limit the use of extrinsic evidence, not to require judges to
admit it. Presenting jurors with details of one wrongful im-
prisonment (especially on a mistaken charge of terrorism)
would appeal to their emotion rather than to their reason.
Emotional responses can be strong, but reason should un-
derlie a verdict.
    Bonds had ample opportunity to supply the jury with ev-
idence about the reliability of the ACE-V method, including
the extent to which changes the FBI made in the last decade
have improved its reliability. Shortly after the Mayﬁeld ﬁas-
co the National Research Council concluded that the ACE-V
method is too subjective and too unreliable to deserve the
label “scientiﬁc.” Strengthening Forensic Science in the United
States: A Path Forward 136–45 (2009). More recently, the Pres-
ident’s Council of Advisors on Science and Technology con-
cluded that changes in ACE-V have bolstered its accuracy.
Forensic Science in the Criminal Courts: Ensuring Scientiﬁc Va-
lidity of Feature-Comparison Methods 87–103 (2016). This report
concluded that the error rates shown by well-designed stud-
ies ranged from 1 in 18 to 1 in 604. (These are rates of false
positives—incorrectly declaring a match when the prints
4                                                           No. 18-2670

diﬀer—taking account of statistical conﬁdence intervals.)
The bofom line (id. at 101–02; emphasis in original):
    Foundational validity. Based largely on two recent appropriate-
    ly designed … studies, [we ﬁnd] that latent ﬁngerprint analysis
    is a foundationally valid subjective methodology—albeit with a
    false positive rate that is substantial and is likely to be higher
    than expected by many jurors based on longstanding claims
    about the infallibility of ﬁngerprint analysis.
    Conclusions of a proposed identiﬁcation may be scientiﬁcally
    valid, provided that they are accompanied by accurate infor-
    mation about limitations on the reliability of the conclusion—
    speciﬁcally, that (1) only two properly designed studies of the
    foundational validity and accuracy of latent ﬁngerprint analysis
    have been conducted, (2) these studies found false positive rates
    that could be as high as 1 error in 306 cases in one study and 1
    error in 18 cases in the other, and (3) because the examiners were
    aware they were being tested, the actual false positive rate in
    casework may be higher. At present, claims of higher accuracy
    are not warranted or scientiﬁcally justiﬁed. Additional … studies
    are needed to clarify the reliability of the method.
    Validity as applied. Although we conclude that the method is
    foundationally valid, there are a number of important issues re-
    lated to its validity as applied.
        (1) Conﬁrmation bias. Work by FBI scientists has shown that
        examiners typically alter the features that they initially mark
        in a latent print based on comparison with an apparently
        matching exemplar. Such circular reasoning introduces a se-
        rious risk of conﬁrmation bias. Examiners should be re-
        quired to complete and document their analysis of a latent
        ﬁngerprint before looking at any known ﬁngerprint and
        should separately document any additional data used dur-
        ing their comparison and evaluation.
        (2) Contextual bias. Work by academic scholars has shown
        that examiners’ judgments can be inﬂuenced by irrelevant
        information about the facts of a case. Eﬀorts should be made
No. 18-2670                                                               5

       to ensure that examiners are not exposed to potentially bias-
       ing information.
       (3) Proﬁciency testing. Proﬁciency testing is essential for as-
       sessing an examiner’s capability and performance in making
       accurate judgments. As discussed elsewhere in this report,
       proﬁciency testing needs to be improved by making it more
       rigorous, by incorporating it within the ﬂow of casework,
       and by disclosing tests for evaluation by the scientiﬁc com-
       munity.
   From a scientiﬁc standpoint, validity as applied requires that an
   expert: (1) has undergone appropriate proﬁciency testing to en-
   sure that he or she is capable of analyzing the full range of latent
   ﬁngerprints encountered in casework and reports the results of
   the proﬁciency testing; (2) discloses whether he or she docu-
   mented the features in the latent print in writing before compar-
   ing it to the known print; (3) provides a wrifen analysis explain-
   ing the selection and comparison of the features; (4) discloses
   whether, when performing the examination, he or she was aware
   of any other facts of the case that might inﬂuence the conclusion;
   and (5) veriﬁes that the latent print in the case at hand is similar
   in quality to the range of latent prints considered in the founda-
   tional studies.

This summary provides the defense bar with paths to cross-
examine witnesses who used the ACE-V approach. Have
they avoided conﬁrmation bias? Have they avoided contex-
tual bias? Has their proﬁciency been conﬁrmed by testing?
Cf. Florida v. Harris, 568 U.S. 237, 247–49 (2013). And the re-
port’s observation about the rate of false positives will in-
form jurors that TV shows do not depict the actual state of
latent-ﬁngerprint analysis. Bonds does not contest any re-
strictions the district court placed on how these mafers were
explored on cross-examination; his sole appellate contention
is that the court erred by preventing reference to Mayﬁeld.
6                                                   No. 18-2670

    To say that an error rate is troubling is not to suggest that
ACE-V is too uncertain for use in litigation. Assessment
must be comparative. What are the alternatives? Grainy pic-
tures taken by bank surveillance cameras of robbers wearing
masks, or confederates who testify for the prosecution, have
problems of their own. Witnesses may lie on the stand; there
is no science of credibility enabling jurors to detect who is
telling the truth, and some witnesses who think that they are
telling the truth nonetheless may be confused or incorrect.
Eyewitness identiﬁcation is notoriously subject to the vagar-
ies of memory. A judicial system that relies heavily on falli-
ble lay testimony cannot be improved by excluding profes-
sional analysis that may well have a lower error rate—or by
diverting jurors’ afention to particular errors made by other
analysts years earlier. What the judicial system can do is sub-
ject the forensic evidence to cross-examination about a
method’s reliability and whether the witness took appropri-
ate steps to reduce errors. Bonds enjoyed that opportunity.
                                                      AFFIRMED
