Excluding Sleep Deprivation Expert Under FRE 702

Fourth Circuit underscores the requirement that expert testimony must be helpful to the jury in determining the facts of the case; the exclusion of the sleep deprivation expert testimony, offered to explain the various inconsistent statements made by the defendant, was not helpful to the jury under FRE 702 and did not interfere with the defendant's Sixth Amendment right to present a defense, in United States v. Lespier, _ F.3d _ (4th Cir. Aug. 6, 2013) (No. 12-4266)

As noted yesterday in the Federal Evidence Blog, a prerequisite to admit expert testimony under FRE 702 is that the specialized knowledge of the expert must be helpful to the jury. If the helpfulness requirement is not met, it does not matter if all the other conditions for expert testimony are satisfied. A recent Fourth Circuit case highlights how expert testimony may be excluded for failure to establish the helpfulness requirement.

Trial Court Proceedings

In the case, defendant Lespier was prosecuted for murdering his former girlfriend on an Indian reservation. When the defendant was interviewed by law enforcement, he provided exculpatory statements that were inconsistent with the evidence including an autopsy of the victim. At trial, the defendant sought to introduce "an expert in human psychology to offer testimony concerning the alleged inconsistencies in the statements made by the Defendant and to offer an opinion as to possible reasons for such alleged inconsistencies." Lespier, _ F.3d at _. He contended that this expert testimony was essential for his defense. The trial court excluded the exert testimony as unhelpful to the jury. The defendant appealed, contending that the exclusion denied him "a meaningful opportunity to present a complete defense" under the Sixth Amendment since the "inconsistencies were used to impeach his statements’ credibility" which therefore "prejudiced his ability to mount a defense." Lespier, _ F.3d at _ (citing Crane v. Kentucky, 476 U.S. 683, 690 (1986) (internal quotation marks omitted); Washington v. Texas, 388 U.S. 14, 19 (1967) (noting “the right to present a defense . . . is a fundamental element of due process”)).

Circuit Analysis

The Fourth Circuit affirmed the exclusion of the proffered testimony. In addressing the constitutional issue first, the circuit noted that while the Sixth Amendment ensures that a defendant has "a meaningful opportunity to present a complete defense," the exclusion under the FRE does not necessarily "contravene[] the Constitution or otherwise amounted to error." Lespier, _ F.3d at _.

The circuit concisely explained that defendant failed to show that the expert testimony on sleep deprivation would be helpful to the jury:

The helpfulness requirement of Rule 702 thus prohibits the use of expert testimony related to matters which are “obviously . . . within the common knowledge of jurors.” Scott v. Sears Roebuck & Co., 789 F.2d 1052, 1055 (4th Cir. 1986). The assessment of a witness’s credibility, as we have explained, is “usually within the jury’s exclusive purview.” United States v. Dorsey, 45 F.3d 809, 815 (4th Cir. 1995). Thus, in the absence of unusual circumstances, Rule 702 renders inadmissible expert testimony on issues of witness credibility.

We have recognized a narrow exception to the general rule. See United States v. Harris, 995 F.2d 532, 534-36 (4th Cir. 1993) (affirming exclusion of expert testimony on validity of eyewitness identification, but recognizing possible admissibility of such evidence in narrow circumstances). Nevertheless, we agree with the government that, in the typical case, the effects of sleep deprivation, like problems with eyewitness identifications, are readily comprehended by jurors and do not require an expert for their explanation. Simply put, the trial court did not abuse its discretion in excluding Lespier’s expert on the basis that his testimony would “intrude[] on the jury’s role regarding the assessment of the credibility of witnesses.”

Lespier, _ F.3d at _ (omitting footnote and other citations).


The Lespier case demonstrates the role of the helpfulness requirement for expert testimony under FRE 702. The jury did not require an expert to assess whether any sleep deprivation may have explained the various exculpatory inconsistencies provided by the defendant. These matters were within the "common knowledge" of the jury. Further, since the defendant raised the importance of credibility to his defense, the circuit concluded that the area of expertise also interfered with the jury's ability to assess the credibility of witnesses, a core role fulfilled by the jury.


Photo Description: Fourth Circuit, Lewis F Powell, Jr. United States Courthouse in Richmond, VA.


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