EvidenceProf Blog

Editor: Colin Miller
Univ. of South Carolina School of Law

Friday, January 11, 2019

Supreme Court of Alaska Shuts the Door on Comparison Question Technique Polygraph Evidence

Polygraph evidence is inadmissible in 49 states (the exception being New Mexico). Therefore, it might surprise you that Alaska courts allowed for the admission of a particular type of polygraph test in two recent cases. But, as a result of the recent opinion of the Supreme Court of Alaska in State v. Sharpe, 2019 WL 99081 (Alaska 2019), this test won't be admissible in the future.

In all both of the cases, a “comparison question technique” (CQT) was used by David Raskin, Ph.D., a polygraph examiner:

The CQT exams Dr. Raskin administered in these cases are a form of specific-incident polygraph testing, as opposed to a polygraph examination for screening or background check purposes. Screening tests ask about a broad range of conduct, such as whether the examinee has ever committed a crime or used illegal drugs, but specific-incident tests, like the ones Dr. Raskin administered, focus on a particular crime, event, or other occurrence under investigation. The CQT examiner asks three types of questions: “neutral” or “irrelevant” questions (“Is your name Thomas?”), broad “control” or “comparison” questions (“During the first 35 years of your life, did you ever engage in a sexual act of which you should be ashamed?”), and specific “relevant” questions (“Did you ever touch G.B.’s breast?”). Each comparison question will ask about a broad category of past conduct, similar to but excluding the specific occurrence being investigated, and each question will be specifically designed to be ambiguous, broad, and vague but elicit a “No” answer. Because the comparison questions are broadly worded and address sensitive topics, the examinee is assumed to be deceptive or at least unsure of his answer. The underlying rationale of the CQT is that deceptive subjects will feel more threatened by the relevant questions and will view the comparison questions as less important; thus, deceptive subjects will have a stronger physiological reaction to the relevant questions. In contrast, truthful subjects are expected to feel more threatened by the comparison questions and will have a stronger physiological reaction than to the truthfully answered relevant questions.There are two reasons for this expectation: first, the sensitive topic of the comparison questions is assumed to generate a response; second, the examiner will have explained prior to the exam that the examinee’s reactions to the comparison questions are important to the ultimate test result. Thus, the CQT is based on the premise that the relative magnitudes of the examinee’s reactions to the relevant and comparison questions are indicative of his truthfulness or lack thereof when answering the relevant questions.
The examiner asks the examinee a list of prepared questions multiple times. For each relevant question, the examiner will compare the subject’s reaction to his reaction to an adjacent comparison question.4 Each measured parameter is given a numerical score for each question pair, for example from -3 to +3, with a positive number indicating a stronger reaction to the comparison question and a negative number indicating a stronger reaction to the relevant question. The examiner totals the numerical scores: a high positive overall score is interpreted as indicating a truthful result; a high negative score is interpreted as indicating deception; a score close to zero, whether positive or negative, is considered inconclusive.

In finding that this CQT evidence was improperly admitted, the Supreme Court of Alaska applied the Daubert test and concluded as follows:

(1) Whether CQT polygraphy can be, and has been, empirically tested.

"[G]iven the fact that certain assumptions of polygraph testing not only are untested, but may be functionally untestable, we conclude that this factor weighs decidedly against admitting polygraph testimony as scientific evidence."

(2) Whether CQT polygraphy has been subjected to peer review.

"[A]lthough studies regarding CQT polygraphy have been published in peer-reviewed journals, it does not appear that this has resulted in the kind of refinement and development that makes publication and peer review relevant to a Daubert analysis."

(3) Whether CQT polygraphy has an acceptable error rate.

"Absent some reliable estimate of this base rate there is no way to estimate the reliability of polygraph results, and thus no way to determine whether any particular accuracy rate is acceptable."

(4) Whether there are adequate standards for operating CQT polygraphy.

"It is clear that some aspects of the test lack standards, or at least consistent standards. Specifically, the formulation and ordering of questions, the conducting of the pretest interview, the choice of scoring system, and the evaluation of the examinee’s demeanor leave much to the examiner’s discretion."

(5) Whether CQT polygraphy is generally accepted in the relevant scientific community.

"Given the decades-long debate over the validity of polygraph evidence, the apparent lack of development in the technique as a response to that debate, and the apparently lackluster support for the technique outside the community of practicing polygraph examiners, we conclude that this factor also weighs against admitting polygraph evidence."

Therefore, the Supreme Court of Alaska found that the CQT polygraphy evidence was inadmissible in these 2 cases and inadmissible going forward.



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