What are Polygraph Examinations?
The polygraph test, otherwise known as the lie detector test, is a procedure designed to examine the physiological responses of individuals in order to determine whether they are telling the truth. It measures several bodily functions that are controlled by the subconscious brain, including heart rate, blood pressure, respiration and skin conductivity (also known as galvanic response). A motion sensor is also attached in order to monitor whether the individual being tested is behaving nervously.
During a polygraph test, the baseline values of these functions will be established while the individual is asked neutral questions. Then, the polygraph will ask three relevant questions – such as "did you commit this robbery?" – and will track the physiological responses to these questions. Credible testing facilities have determined that roughly 95 percent of individuals who are truthful will produce a higher response during "yes" responses and a lower response during "no" responses than those who are untruthful. Based on the results of the test , the facility will determine whether the individual was being truthful.
The scientific community is split on the validity of polygraph tests. While the Phillipsburg, N.J. police department believes the polygraph to be useful when paired with other investigative tools, the American Psychological Association has repeatedly stated that there is no scientific evidence to prove that people respond differently to lies than to truths while taking a polygraph test. The APA claims that psychological studies have found no significant difference between the answers and reactions given by those telling the truth and those telling lies, and that the only investigative use for the polygraph test is in evaluating persons deemed likely to be deceptive based on the results – in a limited role.
Are Polygraph Examinations Admissible in Court?
In all but two states, polygraph tests offer the potential of revealing information regarding the truthfulness of a witness. Courts rule in many cases that these tests provide information that might be interesting and helpful to a jury, but which is not reliable enough for jurors to base a verdict upon. A jury which is allowed to base its verdict on polygraph test results may be misled into accepting unreliable evidence as trustworthy.
In fact, the United States Supreme Court established in the 1980 case United States v. Scheffer that "there is simply no consensus that polygraphs [are] sufficiently reliable to warrant admissibility in the courts."
The bulk of the skepticism surrounding polygraph tests and their admissibility to courts stems from the fact that there are many factors which may interfere with or mitigate the reliability of the results. For example, a subject of a polygraph test who has just eaten a meal may be found to have inaccurately elevated baseline respiration and perspiration levels. By the same token, other medical conditions such as diabetes and Beriberi can affect polygraph test results. The parties to a trial may agree to allow the results of a polygraph test to be admitted into evidence.
In either case, the court will likely require that both the proponent’s and opponent’s expert witnesses agree upon the parameters which will be utilized in administering the polygraph test. The courts may also require that the opposing party’s attorney cross-examine and qualify the polygraph examiner as a witness, and/or limit the scope of admissibility to a certain number of questions.
Admissibility in Federal and State Courts
There are differences in admissibility of polygraph test results at the federal level as compared to state courts And there are differences among individual states as well. Nevertheless, 39 states have banned the use of polygraph tests by law. In those states in which it is permitted, the requirement is that both the employer and the employee must agree to the test. The results may be admitted in evidence only if both the employer and the employee agree in advance to the admissibility of the results. It is not uncommon for the results of a voluntary polygraph to be barred in evidence for various reasons, even where not statutorily barred. The Federal Employees Polygraph Protection Act of 1988 is a substantial limitation on polygraph testing. It intends to limit "the use of federal government and private employers in situations where commonly used law enforcement tenets of testing for truthfulness may not be reliable." In addition to limiting federal employers from administering pre-employment tests, it also prohibits employers in the private sector from requiring such tests, although some exemptions are provided. As for state law, in recent years, Arizona and Florida have joined the ranks of those states that allow admissibility of the results of a polygraph test. For example, Florida allows admissibility, but does not require that, if it is mutually agreed to by the parties, the results of a polygraph test shall be admitted into evidence in a criminal proceeding. The Florida law further provides that the admissibility of polygraph results shall be determined under state law. Any state that has not adopted any procedure like Florida’s leaves the determination of admissibility to the trial judge seated in that state. Two statutes in Nevada, enact legislation in both the criminal and civil context, allowing the admissibility of the results of a polygraph test. Finally, Utah passed a law in 2007 that provides for admissibility in civil matters of polygraph test results. Some states, like Maine, have banned the use of polygraph tests by law but have made an exception for criminal investigations in cases of child sex abuse. New Jersey does not allow polygraph tests results into evidence, barring them under all circumstances except with the consent of the subjects of the tests.
Cases and Examples
In the context of current debates on the admissibility of polygraph tests in court, it is important to consider how have courts in the past decided when it comes to admitting these tests as well as cases in which they have ruled them out. These cases form the basis of what courts today consider when denying or permitting the admittance of polygraphs as evidence in a case.
One of the biggest cases with regards to polygraph admissibility was United States vs. Piccinon, a 1988 decision by the U.S. Court of Appeals for the 11th Circuit. In this case, the defendant was accused of bank robbery, and his attorney requested that he take part in a polygraph test. Prior to the testing, the examiner reviewed information with the defendant from law enforcement officials outlining reasons they believed him to be guilty. The defendant was polied, but the examiner recommended that the results be released exclusively to the defendant’s attorney and not presented to the court or prosecutor due to his physical and mental condition, and the stress of the exam. This request was denied , and the court mandated that "should the results be utilized in any way" they be made available to the prosecution. The defendant was found guilty. After being found guilty, the defendant appealed, and the 11th Circuit Court agreed that the statement that the polygraph and its results would be made available to the prosecution was prejudicial. They believed that the defendant’s constitutional rights were violated through the release of results of the polygraph. In their decision, the court wrote: "Because of defendant’s particular vulnerability, those circumstances suggest an inherent tendency within the polygraph system to implicate the defendant in the commission of the crime under investigation. To permit the prosecution to use the results, or even the fact of the polygraph test, is tantamount to allowing the prosecution to introduce an extrajudicial confession inadmissible per se under state law." The 11th Circuit’s decision has been backed up by subsequent rulings. In the case of U.S. v. Simmonds, the court also said it would be prejudicial to release the entire polygraph and all of its results to the prosecutor, saying it would undo future admissibility.
Pros and Cons of Admissibility
Proponents of polygraph tests argue that the tests are a reliable way for courts to determine truthfulness in court. They maintain that the accuracy of the tests are comparable to the accuracy of other forensic evidence, such as fingerprint or bloodstain pattern analysis. In addition, supporters of the admissibility of these tests argue that the legal system has previously allowed these tests to be admissible in courts and that by disallowing their use, witnesses in investigations attempting to tell the truth are forced to have their honesty judged by "a polygraph test among a battery of investigative techniques," a more costly and intrusive action. Proponents of polygraph tests express concern that juries are given no instruction explaining the comparisons between the reliability of a polygraph test and reliability of other types of forensic evidence.
Opponents of the admissibility of polygraph tests believe that polygraph testing is an unreliable method of detecting deception. Opponents maintain that there is no scientific evidence of causation, and this goes both ways; truthful individuals can exhibit signs of deception, while dishonest people can show signs of truthfulness. The National Institute of Justice reported on polygraph evidence in 2002, expressing that "questions remain about the validity of the polygraph as an accurate measure of lying or truthfulness." The general consensus outside of the legal system is that polygraph testing is not an accurate measure of truthfulness.
Future of Polygraph Usage
The future of polygraph use in legal systems, therefore, may well lie in the balance between legislative guidance, scientific validation, and judicial acceptance. As more states and jurisdictions grapple with admissibility, the trend could sway in either direction, depending on the outcome of ongoing debates and studies. In particular, recent technological advancements in computer-based testing and the development of new methods for collecting and analyzing physiological data promise both to raise new evidentiary questions and to provide new means for polygraph and lie detection to be used in the legal context.
Moreover, the legislative guidance from other nations, such as Israel and Hungary, may not be wholly evident in other Western jurisdictions, but the implications of those legislative decisions loom large in European and Asian contexts . In some respects, it may be easier for non-Western jurisdictions to embrace the lie detection industries given a lack of previous psychological and sociological tradition against the use of these tools. In this sense, the use of polygraph tests in legal systems may continue to expand into areas where Eastern or non-Western legal traditions are prevalent.
The legal admissibility of the polygraph test outside the United States has produced varying results. Some nations have heavily regulated its use, only allowing specially trained personnel to administer polygraph tests. Other countries, however, such as Australia and New Zealand, do not currently allow for any judicial use of polygraph evidence or even in pre-trial assessments. Along with continuing scientific validation, international debates on the merits of polygraph tests may ultimately push many jurisdictions toward a similar measure of restricting legal admissibility and use.