CLPEX Chat Board

In November 2017, a state appellate court did something almost unprecedented: It held that a
trial judge made an error by admitting testimony on latent fingerprinting. In State v. McPhaul,
the North Carolina appellate panel found error in admitting expert testimony, based on the lack
of evidence that the expert reliably reached conclusions about the fingerprint evidence. The panel
did not reverse the defendant’s conviction, however, finding the error to be harmless. The ruling
has broader significance for as-applied challenges to the forensic testimony commonly used in
criminal cases, in which judges have often not carefully examined reliability either for many forensic
methods in general, or how they are applied in a given case. Many forensic techniques rely on
the subjective judgment of an expert, who may not be able to fully explain how they concluded
that a fingerprint, ballistics, or other types of pattern evidence is a “match,” except to cite to their
own judgment and experience. In this essay, I describe the scientific status of fingerprint evidence,
the facts and the judicial reasoning in McPhaul, and the implications of the decision. This sleeper
ruling should awaken interest in the reliable application of forensic methods in individual cases

However, when Wood testified to her ultimate conclusions, she was unable to establish that she reliably applied the
procedure to the facts of this case:

[THE STATE:] As to State’s 35-A in Item 113, can you again demonstrate to the Jury the comparison between 35- A and 113?

[WOOD:] State’s Exhibit 35-A is a latent print from the driver’s door and it contains the left index finger of a fingerprint card bearing the name of [defendant].

Q. And upon what is that conclusion based?

A. My training and experience. (emphasis mine)

Q. In looking at the individual minutia with those two fingerprints; is that correct?

A. That’s correct, the process I explained earlier.