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South Dakota Supreme Court Still Doesn’t Trust Polygraphs

Last updated on 2023-09-09

Last year, lying killer Jason Ravnsborg made a big deal in his defense against impeachment of his willingness to take a polygraph test and of investigators’ choice not to administer one. That emphasis on polygraph evidence further demonstrates the ignorance of Ravnsborg, who pretended to be South Dakota’s top lawyer for three years until his impeachment and conviction last summer.

Had Ravnsborg been paying attention to anything other than his desperate political ambitions, he would have been aware that the South Dakota Supreme Court has a well-established rule, invoked for decades and cited just this week in its rejection this week of another killer’s appeal, “prohibiting the admission of polygraph evidence in criminal and civil cases.” The court explained the rule in a 2018 case, State v. Bertram, in which yet another killer appealing to introduce polygraph evidence was represented by Michael Butler, Ravnsborg’s impeachment attorney:

As the State points out, this Court has consistently held that polygraph-test results are not admissible. E.g., In re Fuller, 2011 S.D. 22, ¶ 25 n.4, 798 N.W.2d 408, 414 n.4; Sabag v. Cont’l S.D., 374 N.W.2d 349, 352 (S.D. 1985) (“In South Dakota criminal cases, polygraph results are not admissible evidence.”). This per se rule is based on evidentiary Rules 402 (relevancy), 403 (probative value), and 702 (expert-witness testimony):

The rationale advanced for not admitting evidence of polygraph results, in civil or criminal cases, is that such evidence is irrelevant because of dubious scientific value [(Rule 402)], it has no “general scientific acceptance as a reliable and accurate means of ascertaining truth or deception,” it is not reliable [(Rule 702)], it has no probative value, and it is likely to be given significant, if not conclusive weight by the jury, so that “the jurors’ traditional responsibility to collectively ascertain the facts and adjudge guilt or innocence is thereby preempted” [(Rule 403)].

Sabag, 374 N.W.2d at 353 (citations omitted) (first quoting State v. Green, 531 P.2d 245, 251 (Or. 1975); and then quoting United States v. Alexander, 526 F.2d 161, 168 (8th Cir. 1975)). This Court has strictly adhered to this rule. See State v. Muetze, 368 N.W.2d 575, 587-88 (S.D. 1985) (rejecting admission of polygraph-test results offered to impeach a witness’s testimony) [South Dakota Supreme Court, State v. Bertram, 2018.01.10, pp. 8–9].

In a footnote, the 2018 Bertram Court said it could consider polygraph evidence in the future, but only with “at a minimum, strong evidence that the technology has advanced to such a degree that [polygraphs] are generally accepted as reliable in the scientific community.” The defense in State v. Banks, in which the Court last week reaffirmed its rule against polygraph evidence, offered no such evidence.

The South Dakota Supreme Court’s rule against polygraph evidence existed long before last week’s Banks ruling and long before the 2018 Bertram ruling. One would think that Ravnsborg, who took office as Attorney General in 2019, would have been aware of that fact and not tried pinning his defense on investigators’ lack of interest in evidence that the courts would have rejected. But Ravnsborg never was very good at lawyering. Maybe the State Bar should make him retake the bar exam before letting him practice again.