In United States v. Knowles, No. 16-16802 (May 15, 2018) (Jordan, Martin, Ginsburg), the Court concluded that the district court erred by excluding lay identification testimony, but it found the error harmless.
The district court had admitted under Rule 701 identification testimony from a government witness. The Court rejected the defendant's argument that the testimony should have been excluded under Rule 403 because the witness was a law enforcement official who participated in the vehicle stop uncovering the incriminating evidence. The official's familiarity with the defendant -- and thus the basis of his identification testimony -- was based in part on his observations of her during the traffic stop, and so it did not reveal any past or collateral contact by the defendant with the criminal justice system.
The Court, however, agreed with the defense that the district court erred by excluding defense identification testimony under Rule 701. The Court applied the "equal treatment" principle used in the context of expert witnesses to the context of lay witnesses. The defense witness was even more familiar with the defendant than the government's witness, and so he too should have been permitted to testify on the issue of identification. And Rule 403 would not have barred that testimony, even though he had also served as an expert witness for the defense. However, the Court concluded that the exclusion of his lay testimony was harmless, because the defense presented two former co-workers who provided identification testimony that would have rendered the excluded testimony cumulative.