State v. Black  

As a general rule, one witness may not comment on the credibility of another witness, either through direct comments or through statements that are “tantamount” to stating another witness is credible. State v. Chandler, 360 Or 323, 330-331 (2016). Expert testimony is inadmissible under this rule when the primary effect of the testimony is to assist the jury’s assessment of witness credibility. State v. Beauvais, 357 Or 524, 545 (2015).

Defendant appealed a judgment of conviction for multiple sex offenses involving minors. Defendant assigned error to the trial court’s prohibiting his expert witness from testifying. On appeal, Defendant argued the trial court’s conclusion that the expert testimony was tantamount to improper comment on the credibility of another witness was erroneous. Defendant asserted the testimony was relevant (OEC 401) and admissible as expert witness evidence (OEC 702). As a general rule, one witness may not comment on the credibility of another witness, either through direct comments or through statements that are “tantamount” to stating another witness is credible. State v. Chandler, 360 Or 323, 330-331 (2016). Expert testimony is inadmissible under this rule when the primary effect of the testimony is to assist the jury’s assessment of witness credibility. State v. Beauvais, 357 Or 524, 545 (2015). The Court of Appeals concluded the testimony would be tantamount to commentary on the child witnesses’ credibility because Defendant’s expert intended to suggest to the jury that the child witnesses were not telling the truth because the state’s interviews with the children did not meet established protocols. Thus, the Court held the trial court did not err in prohibiting the expert from testifying. Affirmed.