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 Judges.

EASTERBROOK, Circuit Judge. A jury convicted Myshawn 

Bonds of bank robbery, 18 U.S.C. §2113(a), and a judge sentenced 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 identified Brandon Mayfield as a person whose fingerprints suggested 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 resulted from operational errors. The United States released 

Mayfield, apologized, and paid him substantial compensation. 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, comparison, 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 reliability 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 exclude evidence about Mayfield’s mistaken identification and 

arrest violated the Confrontation Clause of the Constitution’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 imprisonment (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 underlie a verdict.

Bonds had ample opportunity to supply the jury with evidence 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 fiasco 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 President’s Council of Advisors on Science and Technology concluded that changes in ACE-V have bolstered its accuracy.

Forensic Science in the Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods 87–103 (2016). This report 

concluded that the error rates shown by well-designed studies 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 appropriately 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 information 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 related 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 serious risk of confirmation bias. Examiners should be required to complete and document their analysis of a latent 

fingerprint before looking at any known fingerprint and 

should separately document any additional data used during 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 biasing information.

(3) Proficiency testing. Proficiency testing is essential for assessing 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 community.

From a scientific standpoint, validity as applied requires that an 

expert: (1) has undergone appropriate proficiency testing to ensure 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 documented the features in the latent print in writing before comparing it to the known print; (3) provides a wrifen analysis explaining 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 foundational studies.

This summary provides the defense bar with paths to crossexamine witnesses who used the ACE-V approach. Have 

they avoided confirmation bias? Have they avoided contextual bias? Has their proficiency been confirmed by testing? 

Cf. Florida v. Harris, 568 U.S. 237, 247–49 (2013). And the report’s observation about the rate of false positives will inform jurors that TV shows do not depict the actual state of 

latent-fingerprint analysis. Bonds does not contest any restrictions 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 pictures 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 vagaries of memory. A judicial system that relies heavily on fallible lay testimony cannot be improved by excluding professional 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 subject the forensic evidence to cross-examination about a

method’s reliability and whether the witness took appropriate steps to reduce errors. Bonds enjoyed that opportunity.

AFFIRMED