South Dakota’s Top Court Reaffirms Its Refusal To Consider Polygraph Tests To Be Actual ‘Evidence’ Of Anything
It has been known for years that polygraph tests can be beaten. This supposed thing of science can be manipulated to clear guilty people if guilty people know how to trick it.
But law enforcement still likes polygraph tests because they can also be exploited in the other direction. When it's your word against the word of the supposed polygraph expert, any amount of insignificant needle squiggles can be presented as an admission of guilt.
That's why some law enforcement officials think people who teach people to beat lie detectors should be put in jail. And that's why at least one federal law enforcement official thinks anyone calling polygraph testing into question should, at the very least, be subject to criminal investigations.
Like any junk science used most often by law enforcement, polygraph tests can be a double-edged sword. Every so often, the test" clears somebody. That's such a rarity that it's rarely discussed. But it's being discussed again in South Dakota, where a criminal defendant hoped his polygraph test would considered evidence of his innocence.
Casey Bonhorst was killed by a single shot after delivering a Domino's pizza to a Sioux Falls home on the evening of February 26, 2020. Both Banks and Jahennessy Bryant admitted they were there. But each man claimed that he was only the lookout and that the other man pulled the trigger.
Banks wanted to introduce results of a polygraph test at sentencing to support his claim that he wasn't the shooter, but Judge Houwman wouldn't allow it. Justice Patricia DeVaney wrote the Supreme Court's 16-page opinion.
Unfortunately for Raymond Banks, South Dakota courts no longer consider polygraph test results to be evidence of anything. And what's most frequently abused by law enforcement to secure questionable convictions isn't capable of helping this criminal suspect prove his innocence. What's broken is broken for everyone - not just those who believe their lie detector tests results are the actual truth.
From the South Dakota Supreme Court decision [PDF], which local news station KELO actually posted along with its coverage, unlike so many other national news agencies that still seem to believe the only thing anyone needs to read is whatever their reporters have said about a publicly available court decision:
Given the reliability concerns surrounding polygraph evidence, this Court has established a per se rule prohibiting the admission of polygraph evidence in criminal and civil cases. State v. Bertram, 2018 S.D. 4, 14, 906 N.W.2d 418, 423-24. We have explained the basis for this per se rule, citing three rules of evidence, as follows:
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)].
That per se rule also applies to the unusual circumstances of this case, in which Banks sought to have his polygraph test results admitted for consideration by the court during his sentencing, rather than seeking to use these questionable results to establish his innocence.
Either way, it doesn't matter. This state's courts are unable (and unwilling) to consider this particular form of junk science to be admissible, no matter who's seeking to have it admitted or why they're trying to get this done.
And it's not just a rule here. The nation's top court has similarly rejected polygraph test results for the same reason: they simply cannot be trusted.
As the United States Supreme Court stated in rejecting a claim that a rule precluding the admissibility of polygraph evidence is contrary to a defendant's constitutional right to present a defense, there is simply no consensus that polygraph evidence is reliable." United States v. Scheffer, 523 U.S. 303, 309, 118 S. Ct. 1261, 1265, 140 L. Ed. 2d 413 (1998). The Court in Scheffer also observed that there is simply no way to know in a particular case whether a polygraph examiner's conclusion is accurate, because certain doubts and uncertainties plague even the best polygraph exams."
Polygraph test results don't even approach the lowest evidentiary bar for admission in court cases. If anyone wants to prove innocence or guilt, they'll need more than an easily beatable system whose results can be skewed by any expert" asked to testify. That stuff simply isn't welcome in this state's courts or, indeed, a vast majority of courts across this nation.
The circuit court, in refusing to admit Banks's polygraph evidence because of reliability concerns, cited extensive research showing that most state and federal appellate courts considering the admissibility of polygraph evidence at sentencing have upheld refusals to admit this evidence. See, e.g., Ortega, 270 F.3d at 548 (citing numerous cases from other appellate courts). While Banks attempts to distinguish a few of the cases the circuit court cited, he has not refuted the central point that the weight of the authority is contrary to his position. Moreover, given this Court's clearly expressed concerns regarding the reliability of polygraph evidence, Banks has failed to show how the circuit court's ruling would be clearly against reason and evidence..."
This may seem unfair to Banks and his attempt to reduce his 80-year sentence. But if it's not good enough to secure a conviction, it's not good enough to undercut convictions or reduce prison time.