The CAAF has issued an opinion in United States v. Knapp. This case explores the boundary of what law enforcement agents can testify to and not become a human lie detector.
Here, an agent from the Air Force Office of Special Investigations (AFOSI) testified that, using his specialized training, he was able to determine that Appellant was being deceptive when he provided an innocent account of the events in question. We granted review to decide whether this testimony improperly usurped the members’ role in determining witness credibility and, if so, whether it prejudiced Appellant. We hold that the agent’s testimony was impermissible “human lie detector” testimony and, that under the circumstances of this case, it materially prejudiced Appellant’s defense.
The Knapp defense did not object so the court applied a plain error analysis.
Judge Stuckey reminded all that:
“[T]his [C]ourt has been resolute in rejecting the admissibility of so-called human lie detector testimony, which we have described as: ‘an opinion as to whether the person was truthful in making a specific statement regarding a fact at issue in the case.’” [Unied States v.] Brooks, 64 M.J.  at 328 [C.A.A.F. 2007](quoting United States v. Kasper, 58 M.J. 314, 315 (C.A.A.F. 2003)). “If a witness offers human lie detector testimony, the military judge must issue prompt cautionary instructions to ensure that the members do not make improper use of such testimony.” Kasper, 58 M.J. at 315.
* Interestingly both Kasper (OSI) and Brooks (expert) are AF cases. In each there was impermissible credibility testimony, without objection and without a limiting instruction.
Judge Stuckey writing for the Knapp majority tells us that the appellate courts will allow for the following types of testimony.
- it would have been permissible for SA Peachey to describe Appellant’s physical reaction to the interrogation questions.
- It would have been permissible for SA Peachey to explain that this reaction caused him to continue questioning Appellant.
I’m not sure the above examples aren’t just euphemisms or implications of lying by the witness having the same effect of telling the members that the accused lied to him.
Finally, “[W]e conclude that the military judge’s failure to appropriately instruct the members to disregard this testimony was prejudicial error.” Slip op. at 12.
Chief Judge Baker in dissent agreed with the majority that there was error. But he disagreed the error was prejudicial.
For those familiar with Lewis Carroll’s, The Hunting of the Snark, to paraphrase. Perhaps now you’ll know that what we tell you three times is true.
Time! – ring the bell man.