FBI Agent Cannot Testify as Human Lie Detector, Opining On Defendant’s Truthfulness

July 25, 2014Articles

Sometimes, a court opinion reveals the prosecutorial tactic under scrutiny, the lower court’s endorsement of the same and defense attorney’s failure to object to the same, to be a real head-scratcher, a kind of “what in the world could they have been thinking?” experience. The Tenth Circuit recently had such an experience involving a federal prosecutor’s decision to call an FBI agent as an expert witness on truth detection and to have the agent opine as to the deceptiveness of a defendant during a custodial interview; a defense lawyer’s inexplicable failure to object contemporaneously to any portion of that remarkable testimony; and the trial court’s allowance of clearly impermissible opinion testimony in contravention of its Federal Rule of Evidence 702 gateway function.

In United States v. Hill, 749 F.3d 1250 (10th Cir. 2014), a bank robbery suspect gave a custodial interview to FBI Agent Jones, in which the defendant made exculpatory statements challenged by the interviewer. At trial, the videotaped statement was played, although the defendant unsurprisingly did not take the stand. Agent Jones was called as the final witness on the government’s case, qualified as an expert interviewer based on his FBI training and allowed by the trial court, in the face of absolutely no objection to qualifications or the helpfulness of the testimony, to opine on all the ways in which the defendant had revealed himself in the interview to be untruthful: his mumbling; his avoiding certain questions; his use of the phrase “to my knowledge” in answering other questions; his invocation of religious belief; and the like. (For fans of Monty Python, the recap of this testimony is worth reading, if only because its absurdity invokes the “Witch or not a witch” flotation test employed in a skit based on a fictitious version of medieval England).

The Tenth Circuit pointed out that not only was expert testimony on credibility ruled out by its own precedent as to Rule 702, but that every court of appeals to have considered the question had come to the same conclusion. So awfully impermissible was this testimony that even on plain error review, necessitated because defense counsel had lodged no objection at trial, the conviction had to be reversed, making Hill “one of the exceptional cases in which we exercise our discretion to notice the plain error ….” Id. at 1252.