United States v. Butler (2020)

United States Court of Appeals for the District of Columbia Circuit · 2020 · Evidence

955 F.3d 1052 (D.C. Cir. 2020)

Updated August 22, 2026

EvidenceFalse forensic testimonyDue ProcessHair microscopyMaterialityNapueGiglioAgurs

Facts

At Butler's murder trial, the government's FBI hair expert testified that hairs found on the victim's clothing matched Butler's hair in all microscopic characteristics and also suggested that it would be very rare for such hairs to come from different people. Decades later, the government concluded that this testimony exceeded the limits of science because it implied association with a specific individual and assigned unsupported statistical significance to the match. The government's case otherwise relied primarily on testimony from James Hill and Phyllis Gail Robinson, both of whom said Butler confessed to them but whose credibility was vulnerable because of false and inconsistent testimony about drug use and prior statements. Other corroborating evidence included paint analysis, witnesses placing Butler near the scene, and the later discovery of the victim's keys near a place Butler frequented.

Issue

Whether the government's knowing use of false hair microscopy testimony at Butler's trial was material under the Due Process Clause. More specifically, was there any reasonable likelihood that the false hair testimony could have affected the jury's verdict?

Rule

When the government knowingly presents false testimony, due process is violated if the false evidence is material. False testimony is material if it could in any reasonable likelihood have affected the judgment of the jury; the defendant need not show he more likely than not would have been acquitted without it, only that the false testimony undermines confidence in the verdict.

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One of 10 multiple-choice questions for this case. Pick an answer to see why.

In a murder trial in Baltimore, the prosecution knowingly presents a fiber analyst who testifies that carpet fibers on the victim’s coat were "the same" as fibers from Devin Cole’s apartment and that it would be "extremely rare" for such fibers to come from another source. The rest of the case depends mainly on two jailhouse informants who claim Devin confessed, but both were impeached with prior inconsistent statements and motives to curry favor with police.

If Devin later seeks post-conviction relief on due process grounds, which is the strongest argument that the false fiber testimony was material?

Explanation. When the government knowingly uses false evidence, due process is violated if the evidence could in any reasonable likelihood have affected the jury’s judgment. The defendant need not show acquittal was more likely than not. False forensic evidence is especially material when it supplies strong corroboration for witnesses whose credibility is open to substantial attack.