Should Polygraph Tests be Admissible at Trial as Valid Scientific Evidence - Literature review Example

Should polygraph tests be admissible at trial as valid scientific evidence? Since Eve first deceived Adam in the Garden of Eden, mankind has searched for ways to determine truth from deception. The ancient Chinese would have the accused subject chew dry rice, believing that liars would have difficulty because their mouths were dry. Arabs used to brand the tongue of the accused; those injured were liars. During medieval times, combat was employed to determine truth. Those who died were assumed to have been guilty [1]. When an American scientist came up with the idea of a “lie detector” the idea was generously embraced. Test results were considered proof of lying because so many confessions resulted from subjects who failed the test [2]. This can be as misleading as the aforementioned practices in that high rates of false positive results have been associated with polygraph exams. The first polygraph was created by William Marston in the 1920’s. It was built based upon an existing medical instrument that recorded a person’s pulse and blood pressure [3]. Marston was a Harvard-educated psychologist who began researching the idea of a “lie detector” in 1917. By 1923 he boasted a 95% accuracy rate of his machine and its ability to detect lying. The polygraph machines used today differ little from those built in the 1920’s [4]. The literal translation of the word “polygraph” is “many writings.” This title is accurate in describing the charting done by the three components of the test. The machine uses a pneumatic tube to chart depth of respiration, a blood pressure cuff to chart cardiovascular changes, and electrodes on the fingertips to measure galvanic skin conductance [5]. These writings make up a chart of peaks and valleys that is interpreted by either a machine using a specific algorithm or a polygraph examiner. The idea behind the test is that lying creates stress for the person telling the lie, and this stress can be measured by changes in the above physiological responses. The use of the polygraph in the private sector is strictly regulated by the Polygraph Protection Act of 1988; however use by government agencies is not as constrained [6]. According to White in his article Ask Me No Questions, Tell Me No Lies, the Pentagon compels over 23,000 polygraph exams each year, and the majority of the nation’s police and sheriff’s departments use polygraphs as part of their pre-employment screening [7]. The FBI currently requires polygraphs of new agents, as do private companies performing government work, such as nuclear energy facilities, those that engage in the transportation or storage of toxic waste, and those that supply proprietary information, to name a few [8]. Despite the fact that government agencies are exempt from the restrictions facing private employers regarding polygraph testing, there still remain questions as to the reliability and acceptability of the results they produce. Trial and appellate courts are challenged with the task of deciding if the polygraph is scientific evidence or the equivalent of “flipping a coin.” Proponents argue that a calibrated machine operated by a trained professional can be a “valuable probative tool for an employer in testing the truthfulness of job applicants, detecting thieves, and investigating workplace crime” [9]. This may be true, and the accuracy of the test may or may not be a deciding factor in the termination or employment of an employee. But what about a defendant accused of a crime? Instead of a job being at stake, the person’s freedom is in jeopardy. Should polygraph evidence be permitted by the court as either exculpatory or incriminating evidence? Although not created specifically to answer this question, the Federal Rules of Evidence are frequently used in testing whether or not a polygraph should be allowed in trial on a case-by-case basis. Rules 702, 403 and 608 are particularly useful to trial judges and appellate courts trying to determine the answer to this question [10]. Federal Rule of Evidence 702 addresses the scientific validity of an issue [11]. In this case the issue is the “science” of polygraphy. Is it grounded in scientific knowledge? To determine this answer several questions must be addressed. The first focuses on whether or not the science being questioned has been tested. When dealing with polygraphs, there is no question about the equipment’s ability to measure what it is designed to measure. Rather, the arguments are centered on the consistency and reliability of the process and the examiner [12]. There are three different techniques used to administer a polygraph to a subject. Of the three types of tests, the oldest is the relevant-irrelevant (RI) technique. The examiner asks the subject both relevant (related to the incident being investigated) and irrelevant (such as name or birth date) questions. It is expected that a truthful subject will have similar results for either set of questions. If the person is lying, a significant difference is expected in the charting of the two sets of questions. Despite being the oldest polygraph technique, the RI is also the least reliable due to a high number of false-positive results [13]. The control question (CQ) technique is the most commonly used and also uses relevant and irrelevant questions. Again, irrelevant questions have nothing to do with the incident being investigated, but the subject is instructed to answer them falsely. These questions are the control questions and are meant to provoke physiological changes which are compared with results of the relevant questions. As Gallai explains, “A deceptive subject will show greater physiological responses when falsely answering the relevant questions than when falsely answering the irrelevant questions. An innocent subject… will have trouble falsely answering the control questions” [14]. Similar to the CQ technique is the directed lie control (DLC) technique. The major difference between them is that the examiner using the DLC technique emphasizes to the subject that it is very important to lie when answering the control questions because those answers are crucial to the outcome of the test. This is supposed to increase the subject’s stress level and produce greater physiological responses than the CQ technique. There are also documented incidents where the examiner has used a combination of these two techniques [15]. One obstacle to the reliability of polygraphs is the use of countermeasures. One common countermeasure is for the subject to inflict pain upon himself during the control questions (i.e.; placing a tack in his shoe). This causes increases in the measured physiological responses and is intended to result in a false chart that appears similar to the results of the deceptive answers to the relevant questions [16]. For even the unsophisticated liar, countermeasures are easily utilized in an attempt to “fool” the machine. The second requirement of Rule 702 is that the science in question be subjected to peer review and publication [17]. Trial judges frequently find that polygraph testing meets this requirement [18]. Due to the length of time that polygraphs have been in use, as well as the endless debates its use generates, the subject has certainly been subjected to review and has been published extensively. Meeting this requirement alone is not enough to overrule the other three requirements of Rule 702, however [19]. The third requirement addresses error rates and operational standards. In order to calculate an error rate for polygraph results, the actual truth of the incident must be known. This creates a conundrum - if the truth were known, polygraphs would not need to be used. In order to verify accuracy, the truth must be known. Absent this, the best that can be relied upon is the training and experience of the examiner. Unfortunately, there are no regulated training or operating standards for this field [20]. It is entirely plausible that different examiners conducting a test on the same subject will report different results. This can be caused by something as benign as the way the examiner asks the questions [21]. Polygraph tests do not meet this third requirement of Rule 702. Lastly, in order to satisfy the requirements of Rule 702 the science must be generally accepted by the relevant community. The community is this case are physiological experts, few of which accept polygraph testing as a science. The American Medical Association is one of the largest groups that question the reliability of polygraphs [22]. Prior to Rule 702, two Supreme Court cases were used as the criteria to determine the scientific validity of evidence – Frye v. the United States (1923) and Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993). Frye established the test for “general acceptance” [23]. This test requires that in order for expert testimony to be acceptable in court, the subject being testified about must be generally accepted as reliable in that specific field. In this case, William Marston, the initial creator of the polygraph, administered the test to Frye, who was accused of murder. The results were in favor of Frye being truthful about his innocence. The federal appeals court ruled that this was not acceptable evidence because it was not generally accepted in the scientific field [24]. More recently Daubert has superseded the Frye test and established that the Federal Rules of Evidence, particularly 702, are the standard for scientific admissibility [25]. According to the text of the opinion written by Justice Blackmun, “ “scientific” implies a grounding in science’s methods and procedures, while the word “knowledge” connotes a body of known facts or of ideas … accepted as true on good grounds” [26]. It is up to the trial judge to decide what evidence meets these criteria on a case by case basis. Federal Rule of Evidence 403 allows the exclusion of relevant evidence if its probative value is outweighed by other considerations, such as prejudice, confusion, and waste of time [27]. In order to determine if particular evidence satisfies the requirements of Rule 403, the trial judge must first determine probative value. The Daubert test is often used as a basis to establish this factor [28]. The next step is to consider any prejudicial issues affecting the polygraph testing. The Office of Technology Assessment reports that, in addition to racial prejudice (white examiner/black subject or opposite), test results may also be affected by gender and intelligence [29]. White refers to a Chicago case which suggested that false positive results are assigned to blacks more frequently than to whites [30]. Once past this hurdle, the evidence must not usurp the role of the jury [31]. There is a high likelihood that a jury presented with polygraph evidence will give the results more weight than other evidence. The mystery of the “science” combined with the qualification of the examiner as an “expert” may lead juries to conclude that the results are infallible. Another risk is that the jury will rely upon the polygraph results to judge the subject’s credibility instead of their own instincts as they evaluate the subject’s behavior in the courtroom [32]. This point is addressed in United States v. Sheffer [33].The Supreme Court in this case suggested that as a result of polygraph evidence a jury may base a determination of guilt or innocence upon probability rather than fact [34]. The evidence, if determined to be probative, must also be weighed by the trail judge regarding the amount of time consumed by the offering of the evidence relative to its value. It is difficult for polygraph evidence to pass this test, given the distinct possibility that a “battle of expert testimony” would ensue [35]. Spending an inordinate amount of time having experts contradict each other could cause the jury to place too much emphasis on the evidence, or could result in confusing the jury. Either action would result in an inaccurate verdict. One final test to determine if polygraph evidence is admissible in court is Federal Rule of Evidence 608 [36]. The purpose of this Rule is to test whether or not to allow evidence that speaks to the character of a witness, including the defendant. The intent of this is to provide a picture of the general character of the defendant. Unfortunately, the polygraph can only provide a general determination of the truthfulness or deception of the subject at a particular time and pertaining to a specific topic [37]. Also, the polygraph examiner only interacts with the subject in a controlled setting that is most likely stressful and can in no way provide testimony as to the subject’s general character. Subsection (b) of this Rule provides a more appropriate avenue for admitting polygraph evidence because it addresses specific instances of conduct rather than general character [38]. All of these factors – Daubert as well as Federal Rules of Evidence 702, 403 and 608 – can be applied to State of Kansas v. Stephen Medford Shively [39] to determine the admissibility of polygraph evidence specific to that case, although the Kansas State Supreme Court relied heavily on the Frye test in rendering its opinion. In 1995 Topeka police officers conducted a drug raid on defendant Shively’s home. The raid was conducted during the night. During this raid, Shively fatally shot one of the police officers. His claimed that he did not know it was the police breaking into his house and asserted a defense of dwelling defense. In 1996 Shively was tried for intentional second-degree murder, aggravated assault on a police officer, and drug charges. He was acquitted of murder, but found guilty of aggravated assault and all of the drug charges. Part of the evidence offered by the defense was a polygraph taken voluntarily by Shively that concluded he was not being deceptive in relating “his version of relevant events” [39]. The State appealed, arguing in part that the trial judge improperly allowed Shively’s polygraph results into evidence. The trial judge reasoned that the polygraph results were allowed as evidence because new technology, including computerized scoring, made the evidence admissible. It should be noted that polygraph evidence is not permitted in Kansas except by stipulation of both parties. At question is whether new technological advances made polygraphs generally accepted, whereas they weren’t before. As stated prior, the appellate court relied upon the Frye test primarily and determined that polygraph evidence still did not meet the general acceptance requirement. Daubert supersedes Frye and establishes the Federal Rules of Evidence as the standard to be met [41]. First of all, under Rule 702, can the science be tested? As discussed earlier, given the variety of questioning techniques, the lack of uniformity in training examiners, and the use of countermeasures demonstrate that there exists no procedure that can accurately test the polygraph’s validity. Although there has been much publication and peer review on the subject, this does not outweigh the other factors of Rule 702. A reliable error rate cannot be established nor is it generally accepted in the scientific community. For these reasons, Shively would not pass this test. Another reason to disallow the polygraph evidence in this case is that the test does not take into account what the court calls “human elements” such as the psychological and emotional makeup of the examinee. The appellate court also questioned whether polygraph evidence replaces the jury as truthfinder [42]. For these reasons, Shively would not pass this test, either. Although the trial judge may have taken into consideration Rule 608(b), which could be used to support the finding that polygraph evidence can be helpful in determining the defendant’s truthfulness or deceptiveness regarding this specific incident, this is not enough to outweigh the other factors that disallow such evidence. However, this does suggest more appropriate uses for polygraph evidence, such as to corroborate other evidence. The polygraph can also be appropriately used as an investigative tool after a suspect has been identified and proper investigation has been completed [42] to compare with the suspect’s responses to the test questions. The polygraph “science” presents a unique problem to the judicial system in that the technology has changed very little since its inception in the 1920s. Results can now be interpreted by a computer, but the programming is still done by a fallible examiner. Lack of training and consistency of examiners add to the unreliability of the tests. There is no possible way to accurately establish error rates because the truth must be known in order to determine the subject’s truthfulness, but if a polygraph is being used it is implied that the truth is not known. Lacking an across the board ban on the use of polygraphs, the Supreme Court as well as lower appellate courts have been relatively successful in applying tests, such as Frye and Daubert, as well as interpreting applicable Federal Rules of Evidence, to provide consistent rulings that trial court judges can refer to when rejecting or accepting polygraph evidence. These tools provide clear requisites when reviewing admissibility of evidence, and they are likely to be amended as society and technology change the way Americans view the use of the polygraph machine. [1.] White, Richard Jr., “Ask Me No Questions, Tell Me No Lies: Examining the Uses and Misuses of the Polygraph.” Public Personnel Management, Vol. 30, 2001, 483. [2.] Krapohl, Donald J., “Does the Confession Criterion in Case Selection Inflate Polygraph Accuracy Estimates?” Forensic Science Communications, Vol. 4, No. 3 [3.] White [4.] White [5.] White [6.] White [7.] White [8.] Foley, Richard T., Kethley, B., Limpaphayom, W., & Terpstra, D. E., “The Nature of Litigation Surrounding Five Screening Devices.” Public Personnel Management, Vol. 29, 2000, 43. [9.] White [10.] Gallai, D., “Polygraph Evidence in Federal Courts: Should it be Admissible?” American Law Review, Vol. 36 1999, 87. [11.] Fed. R. Evid. 702 [12.] White [13.] Gallai [14.] Gallai [15.] Gallai [16.] White [17.] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). [18.] Gallai [19.] Gallai [20.] Gallai [21.] White [22.] Gallai [23.] White [24.] Frye v. United States, 293 F. 1013 (D.C. Cir 1923). [25.] White [26.] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). [27.] Fed. R. Evid. 403 [28.] Gallai [29.] Office of Technology Assessment (OTA), Congress of the United States, Scientific Validity of Polygraph Testing: A Research Review and Evaluation (Wahington, DC: U.S. Government Printing Office, 1983). [30.] White [31.] White [32.] Gallai [33.] United States v. Sheffer, 118 S. Ct. 1261 (1998) [34.] White [35.] Gallai [36.] Fed. R. Evid. 608 [37.] Gallai [38.] Fed. R. Evid. 608 [39.] Kansas v. Shively 77,100 KS S. Ct. (1998) [40.] Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993) [41.] Kansas v. Shively 77,100 KS S. Ct. (1998) [42.] White BIBLIOGRAPHY Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). US Supreme Court opinion dealing with expert testimony and the “general acceptance” rule. Delivered by Justice Blackmun Read More