What Are Polygraphs?
Polygraph tests are common lie detector examinations, which are designed to determine whether or not the subject is being deceptive when responding to a series of questions. They have actually been around since the early 1900s and are administered by certified examiners by connecting sensors to the subject, using them to monitor their perspiration, pulse rate, and breathing.
The sensors pick up signals and are then interpreted by the examiner . They will ask an extensive list of questions, which they have already asked the subject prior to the test, measuring both physiological and psychological responses to the questions that are asked. Items of confusion between the examiner and the individual are then asked as a follow-up. While these exams are very similar to their depictions in movies and television shows, they are not always foolproof. The results are also not scientifically proven to be accurate.
The Legal Status of Lie Detector Tests
Admissibility of polygraph test results in courtrooms varies by jurisdiction within the United States. All federal courts, except for the United States District of Columbia, have disallowed the use of polygraph evidence. By contrast, the state courts of Hawaii and Utah both allow the use of polygraph evidence under certain circumstances. In many states, the admissibility of polygraph results is based on the type of case to which they are relevant (and most states agree that they are admissible for civil but not criminal cases). Some state courts have admitted polygraph evidence after establishing clear and convincing evidence that using a polygraph test is more probative than unfairly prejudicial or misleading in the specific case. A minority of state courts allow the admissibility of polygraph results if the opposing party is allowed to conduct an independent test, report and share results, as well as cross-examine the polygrapher.
Polygraph Hearing History
The history of admissibility of polygraph results in criminal matters has been long and often muddled. This table provides a sampling of the most pertinent cases involved in the ever-evolving debate:
Case Name
Decision Setting Admissibility
Lyon v. State of Delaware, 225 A.2d 228 (Del. 1967)
A jury was allowed to hear results concerning a voice stress test which attained 100% reliability.
Gottlieb v. State of Florida, 372 So. 2d 1002 (Fla. 1978)
The Florida Supreme Court adopted the Frye test for determining whether to admit a polygraph, as well as a four prong test of reliability.
United States v. Scheffer, 523 U.S. 303 (1998)
The U. S. Supreme Court upheld the prohibition against admitting polygraphs as evidence in courts martial.
Hoey v. State of Arizona
Evidence obtained from a polygraph is inadmissible due to the opportunity to manufacture responses and the subjectivity of the results.
US v. Picciandra, 36 MJ 1173 (1992)
The use of a polygraph was held to be inadmissible in a military tribunal.
Gunhausen v. State of Minnesota, 421 N.W. 2d 377 (Minn. 1988)
MN Supreme Court felt that polygraphs are susceptible to manipulation and deception.
Ervin v. State of Florida, 76 So.2d 356 (1954)
The Supreme Court of Florida held that polygraph results were inadmissible because (1) it did not have a relevance or probative value sufficient to outweigh the unfair prejudice to the jury and (2) its unreliability.
Pros and Cons of Polygraph Test Admissability
The primary reason for the continued resistance to the admissibility of polygraphs is the fact that neither the Supreme Court nor Congress has expressed its endorsement of the device and the results generated by its use. This has apparently led several state courts to conclude that a prerequisite to the admissibility of the results of a lie detector test is the validity of the mechanism itself. A number of courts have concluded, however, that such studies are for the jury to consider and that any question of validity goes to the weight of the evidence rather than its admissibility. To the extent that courts have rejected the introduction of polygraph results, they have mainly focused on the possibility of juror over reliance on the outcomes. Courts have also expressed concern that jurors may be swayed by the opinion of the polygraph technician. And where courts have made meaningful inquiries into the scientific accuracy of the machine, they have relied on purported alternative testing methodologies that the courts concluded were more reliable but which were far less humane. In sharp contrast to the reservations expressed about polygraph admissibility are the scores of state statutes that specifically provide for the admissibility of polygraph results. The proponents of the admissibility of polygraph results in federal court have primarily relied on Daubert and its progeny as ample support for the admissibility of polygraphs. The Supreme Court held in Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), that a trial judge was to act as a gatekeeper to determine if proposed expert testimony would be admissible in court. In evaluating the reliability of expert testimony, a trial judge was instructed to consider such factors as whether the theory or technique can be or has been tested; whether it has been subjected to peer review and publication; in the case of courts[l] though there is no definitive, and authoritative version of the required analysis, an appropriate starting point for the inquiry is whether the theory or technique has been published and subjected to peer review.
Current Admissibility Requirements
The admissibility of polygraph tests in a legal context is a subject that has seen its share of case-by-case litigation as well as statutory evolution since the 1980s. Most of the time, however, the results of polygraph tests are kept out of the courtroom. It’s not that the tests have been shown to be unreliable or irrelevant, but instead that courts and legislatures have moved to eliminate polygraph evidence because there is no uniformity in what is actually being tested.
Statutory rules vary from state to state but many statutes contain some type of restriction on the admissibility of polygraph evidence in criminal cases. Despite individual statutes, the rules contained in the Federal Rules of Evidence and defined in Daubert v. Merrell Dow Pharmaceuticals make it unlikely that a federal court will admit such evidence. Daubert requires the trial judge to be sure that any expert testifies to scientific knowledge that is both relevant and reliable before her testimony is admitted. Daubert applies to all forms of expert evidence.
In most of the states where polygraph results are excluded in the criminal context, there is a threshold requirement that the defendant and prosecution stipulate to the admissibility of the evidence. Prosecutors worry that the typical caveats that accompany polygraph results — stating limitations of reliability and accuracy -would not be needed if the results are introduced.
A recent California appellate case- People v . Kelly -states that a writ of mandate is available to a defendant who wishes to have a polygraph test if the prosecution refuses to identify an expert to pose the test questions. A defendant must file the petition with a description of the test he wants and provide reference to the statute which provides for the polygraph test. A failure the government to timely answer the petition can result in issue preclusion at trial. The defendant must still make a offer of proof to insure that the polygraph test is scientifically valid for the proposed purposes.
Polygraph experts know, and the American Psychological Association has agreed, that the polygraph procedure does not measure truth or lies but only measures autonomic arousal to stress. It is this autonomic arousal that provides the proper basis for admissibility in both civil and criminal proceedings, in appropriate circumstances. In situations where the results are used to cast doubt on a witness’ testimony (which in the civil context would be hearsay) or on circumstantial evidence, for example, the results may be admitted.
In the civil context, California Rule of Evidence 210(b) recognizes polygraph results as relevant. The California Evidence Code also recognizes polygraphs are scientifically valid to prove state of mind. A defendant seeking to exclude polygraph evidence regarding his own deceptive polygraph test pattern should follow the same Kelsey Grammer and Daubert guidelines as a prosecutor does when attempting to exclude a polygraph test. But to overcome Rule 210(b), defendant has the burden of showing that the polygraph test is not scientifically valid.
Law Enforcement Use of Polygraphs
The law enforcement community utilizes the polygraph because of its flexibility and objective nature. The polygraph is a tool that can be applied to nearly any situation. Polygraphs are widely used in pre-employment screening. They save the agencies both money and resources by allowing agencies to weed out applicants who may not display the insistence upon integrity and truthfulness as part of the culture of the agency. The use of polygraphs on current employees of a police department is increasing due to the national prevalence of sexual harassment and other unlawful conduct.
As an investigative tool, the polygraph is often used as a tool of confirmation. If a suspect has an alibi, then the suspect is polygraphed. The results are either inconclusive or indicate deception if the suspect is lying about his or her whereabouts at the time of the alleged offense. As with all criminal investigative tools, the polygraph is only as effective as the person administering the instrument, and the person interpreting the results.
The admissibility of polygraph results remain out of the reach of most criminal suspects. However, the law and public policy are trending toward allowing the admissibility of polygraphs under certain circumstances.
The Future of Polygraph Testing
As scientific advancements continue to enhance the field of polygraph testing, it is possible that newer methods of lie detection will become more widely accepted within the judicial system. For example, a recent study published by the University of Illinois at Urbana-Champaign offers a look into the technology of brain response as a means of detecting deception. The research shows that increased brain activity results during unknown or ambiguous scenarios that are punctuated by morally relevant content — the study’s authors note that unknown situations with a moral aspect elicited more activity in the posterior cingulate cortex than neutral situations. The researchers concluded that the activity of the posterior cingulate cortex could be a meaningful indicator of deception . Although polygraph tests have long been criticized and dismissed by judges and juries, the technology utilized in the University of Illinois study might hold enough value as to stand up in a court of law. However, only time will tell whether jurists will begin to accept these finding as indicative of deception. While lie detection technology has undergone significant changes and updates over the past few decades, it is likely to continue to evolve and improve. As newer technologies are better able to accurately detect deception, more courts will likely become accepting of the science, thereby leading to a shift in the way in which lie detection is utilized within the judicial system.