-The Polygraph Exam - Absolute or Utility Value

    Bob Woolverton authored this paper during his undergraduate work at Bluefield College.  In the paper he refers to RCW 43.101.095(2)(a) which reads:

As a condition of continuing employment for any applicant who has been offered a conditional offer of employment as a fully commissioned peace officer or a reserve officer after July 24, 2005, including any person whose certification has lapsed as a result of a break of more than twenty-four consecutive months in the officer's service as a fully commissioned peace officer or reserve officer, the applicant shall submit to a background investigation including a check of criminal history, a psychological examination, and a polygraph or similar assessment as administered by the county, city, or state law enforcement agency, the results of which shall be used to determine the applicant's suitability for employment as a fully commissioned peace officer or a reserve officer. [Emphasis added]

    The statute does require a police applicant to "submit" to a polygraph or similar assessment, but it does not require the applicant to pass the test, it is supposed to be used as a component of determining an applicant's overall suitability for employment.  The following paper will explain why the polygraph test should not be used as an absolute pass/fail examination.

The Polygraph Examination – Absolute or Utility Value?

In 1998 a Federal law was passed known as the Employee Polygraph Protection Act of 1988, otherwise known as Public Law 100-347.

The law prohibits employers from requiring or suggesting that any employee or prospective employee take a lie detector test; prohibits the use of test results; and prohibits the discharge, discipline, or discrimination against any employee on the basis of test results or for refusal to submit to lie detector testing (National Criminal Justice Reference Service).

            In the interest of national defense and security, exceptions were written into the Employee Protection Act of 1988, which specifically exempts federal and local law enforcement agencies from complying with the law – allowing them to administer lie detector tests, i.e. polygraph tests for employment purposes.  The problem is many law enforcement agencies are utilizing the polygraph test as an absolute pass/fail test regarding consideration of employment, when instead the polygraph test should be used for its utility value, and considered only as a single element of the hiring process.  As a result many law enforcement applicants are being disqualified because of a false-positive result during the polygraph test.  The intent of Public Law 100-347 was to prevent unjust discrimination against honest citizens and not infringe on employees’ or prospective employees’ civil rights as a result of polygraph tests, which have questionable reliability.  The exemption in Public Law 100-347 for law enforcement was not intended to strip law enforcement applicants of their civil rights, but to allow law enforcement employers the ability to use the polygraph exam for the collateral, utility value the polygraph can bring to the interview process.  Instead many law enforcement employers are denying employment to applicants based solely upon the results of a polygraph test – the same type of polygraph test which has not gained sufficient acceptance in the scientific community to be admissible as evidence in a court of law (Grubin & Madsen, 2005, p. 360) – yet many law enforcement applicants are suffering employment discrimination because of this questionable technology and how it is being misapplied under the exemption from Public Law 100-347.

Three Government Research Reports on the Validity of Polygraph Tests

            1.) In 1965, The United States Congress, House Committee on Government Operations, Subcommittee on Government Information and Foreign Operations, released a report titled, Use of polygraphs as ‘lie detectors’ by the federal government.  In that report the committee concluded, “…there was no scientific evidence to support this type of application, and that its evidence base was inadequate.  There is no lie detector, neither man nor machine.  People have been deceived by a myth that a metal box in the hands of an investigator can detect truth or falsehood”(Grubin & Madsen, 2005, p. 362).

            2.) In 1983, acting at the request of the House of U.S. Representatives’ Committee on Government Operations, the Office of Technology Assessment (OTA) conducted a review and evaluation of polygraph tests.  The OTA’s report included statements such as:

·         In 1965 and again in 1976, the House Government Operations Committee concluded that there was not adequate evidence to establish the validity of the polygraph.

·         OTA concluded that the mathematical chance of incorrect identification of innocent persons as deceptive (false positives) is highest when the polygraph is used for screening purposes.  The reason is that, in screening situations, there is usually only a very small percentage of the group being screened that might be guilty.  So, in a typical situation, there may be, perhaps, one person per 1,000 engaged in unauthorized activity.  Therefore, even if one assumes that the polygraph is 99 percent accurate, the laws of probability indicate that one guilty person would correctly be identified as deceptive, but 10 persons would be incorrectly identified (false positive).

·         OTA concluded that, while there is some evidence of polygraph testing as an adjunct to criminal investigations, there is very little research or scientific evidence to establish polygraph test validity in screening situations, whether they be pre-employment, pre-clearance, periodic or a-periodic, random, or dragnet (Scientific validity of polygraph testing: A research review and evaluation).

3.) In 2002, in response to a request by the Department of Energy, the National Academy of Science (NAS) conducted a review on the validity of polygraph tests and reported “…accuracy rates for polygraphy as falling between 81% and 91%, leading [the NAS] to conclude that polygraph tests can discriminate lying from truth telling at rates well above chance, though well below perfection” (Grubin & Madsen, 2005, p. 364).

Specific Data from the 2002 National Academy of Science Report

            The NAS reported research results from laboratory studies regarding the accuracy of polygraph tests tend to over-estimate the accuracy of the polygraph because of the controls the laboratory setting can place on the study which are impossible to control in the field.  In the field polygraph examinations are “plagued by selection and measurement biases” (Faigman, Fienberg, & Stern, 2003, p. 43), which include the skills of the examiner, the quality and clarity of the questions formulated, as well as other environmental factors.  Conversely, the NAS also recognized laboratory studies suffer from a lack of realism.  “In particular, the consequences associated with lying or being judged deceptive in the laboratory almost never mirrored the seriousness of these actions in the real world settings in which the polygraph is used” (Faigman, Fienberg, & Stern, 2003, p. 43).  However, even with these considerations, the NAS stated they believed the results in their report were, “…beyond-the-best case analysis that assumed a greater accuracy level than scientific theory, or validation research suggested could be consistently achieved by field polygraph tests, even in specific incident investigations” (Faigman, Fienberg, & Stern, 2003, p. 43).

            The table shown below is taken from the NAS’s report.  The table shows the results of a polygraph screening test given to 10,000 examinees, in which 10 examinees are guilty of a target offense such as espionage.  The test was administered in two different modes – “suspicious” mode, and “friendly” mode.  In “suspicious” mode, the test is interpreted very strictly with the goal of identifying 80% of the deceptive examinees.  In “friendly” mode the test is interpreted less strictly to protect the innocent, with the goal that fewer than half of one percent of the innocent examinees “fail”.

            As the table below shows, in suspicious mode, the test correctly identified 8 of the 10 spies, but also falsely implicated 1,598 innocent examinees.  These 1,606 examinees will need to be reexamined to find the 8 spies.  Someone who failed this “suspicious” mode test would have a 99.5 percent chance of being innocent.  In the friendly mode, only 39 innocent employees would fail the test, but 8 of the 10 spies would “pass” and be allowed to continue doing damage.  “The committee concluded that for practical security screening applications, polygraph testing is not accurate enough to rely on for detecting deception” (Faigman, Fienberg, & Stern, 2003, p. 44).









Expected results of a polygraph test procedure

with better than state-of-the-art accuracy in a

hypothetical population of 10,000 national laboratory

employees that includes 10 spies.




Suspicious mode: Test is set to detect the great



majority (80 percent) of spies.








Test result






"Fail" test






"Pass" test
















Friendly mode: Test is set to protect the innocent.








Test result






"Fail" test






"Pass" test


















 The Polygraph Machine in Simple Terms

            The modern day polygraph is merely a recording device that records autonomic activities associated with certain questions.  The polygraph records “…heart rate, length of respiration, systolic and diastolic blood pressure, and galvanic skin reactions” (Fiedler, Schmid, & Stahl, 2002, p. 313).  While there is no dispute the polygraph machine does an excellent job recording these physiological functions, multitudes of experts dispute the relationship between these physiological functions and attempts at deception.

            “We know that the technology can give accurate readings about physiology, but there can be no scientific certainty that these changes reflect genuine alterations in the monitored parameters related to lying” (Smith, 2012, p. 113).  “The polygraph does not detect lies, but instead measures physiological responses postulated to be associated with deception.  None of these responses are specific to deception, nor are they necessarily always present when deception occurs” (Grubin & Madsen, 2005, p. 367).  “The fundamental problem is that there is no evidence for a unique physiological response to deception” (Saxe, 1994, p. 70).

            An additional problem related to the consistency of polygraph examinations is the lack of regulations regarding training and/or certification.  The American Polygraph Association is the largest professional association for polygraph examiners, having more than 2,800 members worldwide (About the APA).  “While 20 states require polygraph examiners to be registered with a state board or the APA, there is otherwise little regulation of polygraphy; the APA has no power to sanction poor practice by examiners other than to end their membership” (Grubin & Madsen, 2005, p. 366).  Even though the APA accredits 15 American and four international polygraph schools, there are many polygraph schools open for business with no affiliation with the APA.  Additionally, there is no statutory requirement for any individual to undergo any specific training before purchasing a polygraph machine.  Virtually any individual can purchase a polygraph machine and begin a private business as a polygraph examiner (Grubin & Madsen, 2005).

Real Life Example of a Worst Case Scenario

            In July of 1982, two young boys playing alongside the Green River in King County, Washington, discovered the body of a nude woman.  The woman had been murdered.  Within one month 4 more bodies were discovered in or around the Green River and police realized they had a serial killer on their hands, which came to be known as the Green River Killer.

Some of the victims were young prostitutes known to work an area of Pacific Highway South near the Seattle-Tacoma airport known as the SeaTac strip.  Gary Leon Ridgeway, who lived and worked near the SeaTac strip, became a person of interest in the investigation because of some previous prostitution charges.  Ridgeway agreed to submit to a polygraph test and it was determined by the polygraph test Ridgeway was telling the truth about his innocence.  Around the same time FBI profilers felt the Green River Killer may be a taxicab driver which caused the police to focus on Melvin Foster, a taxicab driver who worked along the SeaTac strip.  Foster submitted to a polygraph examination; however the results of the examination indicated Foster was lying about his innocence related to the murders of these young women.  During the next several years four dozen more women were murdered by the Green River Killer.  Police continued to investigate and conduct surveillance of Melvin Foster’s movements for years.

            In 2001, DNA evidence finally proved Gary Leon Ridgeway was the Green River Killer.  In 2003, Ridgeway confessed to the murders, and also led police to the remains of victims that had not yet been discovered (Gillman, 2007) (Gary Ridgeway.biography, 2013).  This leads one to ask if there was too much emphasis placed on the results of the polygraph, and also serves as a real life (and death) example to substantiate the questionable accuracy of the polygraph examination.

The Polygraph Does Have Investigative Value – Utility Value

            In an article published in the April 2005, edition of the FBI Law Enforcement Bulletin, Special Agent William J. Warner, who serves in the FBI’s Polygraph Unit in Washington, D.C., concedes regarding the debate surrounding scientific certainty of polygraph results.  However, he also says both sides of the debate have missed the target when it comes to the utilitarian value of the polygraph examination.

Confessions, admissions (conceding to some aspect of the crime but not the entire crime), and additional information of investigative value gained through such testing come about due to the utility of the polygraph and the determination of the examiner, irrespective of the instrument’s reliability or validity (Warner, 2005).

            Special Agent Warner emphasizes in his article when subjects believe the polygraph is a valid test for deception they are more likely to voluntarily provide information not previously known.  Special Agent Warner cited many examples where people confessed to crimes at the mere suggestion of scheduling a polygraph examination.  In another example one man confessed to child molestation during the pre-interview.  In yet other examples, on three different occasions men confessed to killing their wives after submitting to polygraph examinations.  Special Agent Warner adds, “This theory has proven successful because any technique that examinees believe to be a valid test for deception likely can produce deterrence and admissions” (Warner, 2005, p. 12).

            In the conclusion of his article, Special Agent Warner emphasizes the point of this entire paper as it relates to the use of a polygraph examination in any investigation, whether it is a security screening or a criminal investigation; “Regardless of its validity or reliability, polygraph testing offers investigators another tool they can employ in interviews to help them obtain additional valuable information” (Warner, 2005, p. 13).


            Any government agency using the Law Enforcement & Security exemption under the Employee Polygraph Protection Act of 1988, and uses the results of that examination as an absolute pass/fail criterion for employment considerations should immediately change their practice.  Those agencies should consider the polygraph only as a collateral tool to obtain additional information.  To do otherwise may ultimately be considered a violation of the examinee’s civil rights, but equally important, since the validity and accuracy of the polygraph examination are subject to intense debate; it is only fair to the examinee to not use the results as the sole deciding criteria.  As shown in the National Academy of Science report, polygraph testing is fraught with false positives, and to render a hiring decision based solely upon the results of the polygraph examination may cause the agency to mistakenly overlook a potentially viable, high-quality candidate.



About the APA. (n.d.). Retrieved November 17, 2013, from American Polygraph Association: http://www.polygraph.org/section/about-the-apa

Faigman, D. L., Fienberg, S. E., & Stern, P. C. (2003, Fall). The limits of the polygraph. Issues in Science & Technology, 20(1), 40-46.

Fiedler, K., Schmid, J., & Stahl, T. (2002, December). What is the current truth about polygraph lie detection? Basic & Applied Social Psychology, 24(4), 313-324.

Gary Ridgeway.biography. (2013). Retrieved November 17, 2013, from Biography.com: http://www.biography.com/people/gary-ridgway-10073409

Gillman, S. (2007, June 10). Does the polygraph test work? Retrieved from ezinearticles.com: http://ezinearticles.com/?Does-The-Polygraph-Test-Work?&id=600366

Grubin, D., & Madsen, L. (2005). Lie detection and the polygraph: A historical review. Journal of Forensic Psychiatry & Psychology, 16(2), 357-369.

National Criminal Justice Reference Service. (n.d.). Retrieved November 16, 2013, from Office of Justice Programs: https://www.ncjrs.gov/App/Publications/abstract.aspx?ID=114964

Saxe, L. (1994, June). Detection of deception: Polygraph and integrity tests. Current Directions in Psychological Science, 3(3), 69-73.

Scientific validity of polygraph testing: A research review and evaluation. (n.d.). Retrieved from Federation of American Scientists: http://www.fas.org/sgp/othergov/polygraph/ota/

Smith, N. (2012, March). Classic projects: Polygraph. Engineering & Technology, 7(2), 112-113.

Warner, W. J. (2005, April). Polygraph testing. FBI Law Enforcement Buletin, 74(4), pp. 10-13.