Deception Detection Techniques Using Polygraph in Trials: Current Status and Social Scientific Evidence

1. IntroductionAlthough not every state in the U.S admits polygraph examination as evidence in trial, the results of the polygraph examination have been presented in some trials as evidence under certain conditions. The results of the polygraph examination are given to the jury usually through expert testimony, or sometimes, the jury hears about the defendant taking the polygraph test at some point of a trial. Generally, in the U.S, polygraph evidence is not admissible in court, but the jury could be given information related to the polygraph in various ways. In the U.S, 18 states1 admit polygraph evidence only when certain conditions are met and the rest do not admit such evidence to the jury or at all with any purposes. Since there are cases in which polygraph evidence is presented to the jury with a certain safeguard (e.g., a stipulation and judge's instructions), even though it is not generally admissible, it is necessary to learn about the uses of polygraph evidence in trial and the status of the social scientific evidence that has accumulated over the last several decades. Furthermore, there needs to be novel research fitted to the situation where polygraph evidence is encountered, based on the legal decision and the social scientific evidence. In this article, therefore, 1) the uses of polygraph in each state in the U.S will be summarized, and 2) the status of the social scientific evidence dealing with the polygraph itself and its effects in trial will be synthesized. Finally, 3) I will provide an outline of what kinds of research have to be done in cooperation will be suggested. For the researchers working on lie detection and jury decision making, this study would provide synthesized information to conduct more qualified and practical studies. Thus, it would contribute to the improvement of related policies, ultimately.2. The Uses of Polygraph in Trials: Analysis by State LevelThe aim of the first section is to summarize the reasons why some states admit polygraph evidence, and, if a state admits the evidence in trial, what the requirements are. The polygraph is, actually, a device for measuring various types of physiological activity, such as electrodermal activity, blood pressure, and respiration, but it is known more commonly as the "lie detector. " This is misleading because a polygraph does not detect lies, but only records physiological activity that each polygraph technique assumes to be along with telling a lie. Regarding the validity, polygraph proponents argue that a polygraph technique (CQT) has over 85% of accuracy (e.g., Abrams, 1989; Ansley, 1983; Honts & Quick, 1996; Raskin, Honts, & Kircher, 1997), while Lykken (1979) asserts that in real-life situations, the polygraph test has a slightly above chance level of accuracy (64% to 71%). Moreover, APA (American Psychology Association) members estimated the validity of polygraph test at about 61% (Iacono & Lykken, 1997). The results of research regarding the validity of polygraph techniques are extremely polarized, which gives rise to controversies about the admissibility of polygraph evidence in trial.The first decision related with the polygraph technique (e.g., systolic blood pressure deception technique) was made in Frye v. United States (1923), which stated that "the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs. " At that time, the technique had not yet met the standard that is known as "general acceptance" and therefore the Court concluded that the evidence would have been rejected. Seventy years later, in Daubert v. Merrell Dow Pharm. , Inc. (1993), the court ruled that "general acceptance" is not a necessary precondition to the admissibility of scientific evidence under the Federal Rules of Evidence, but the Rules of Evidence, especially Rule 702, do assign to the trial judge the task of ensuring that an expert's testimony both rests on a reliable foundation and is relevant to the task at hand. …