To Tell the Truth: A Short History of the Polygraph

The following is a guest post by Annie Ross, an intern with the Digital Resources Division of the Law Library of Congress. She is a recent graduate of political science and international studies at Northwestern University and current library and information science student at Simmons University. She has previously written The Great Chicago Fire, The Animal Welfare Act, and The Legal History of Pigeons.

Last year, 2021, marked the centennial of the invention of the polygraph, popularly known as a “lie detector.” It was developed by several contributors, including William Moulton Marston, the creator of Wonder Woman and her truth-invoking golden lasso. The modern polygraph records multiple physical measures simultaneously: respiration, heart rate, blood pressure, and sweat gland activity. A spike in these measures during questioning is said to reveal stress, and, therefore, potential deception. The accuracy of the modern polygraph, however, has always been in question.

Polygraph Results in Court

Just two years after its invention in 1923, the polygraph was put to the test in a D.C. Circuit Court case, Frye v United States. The Court ruled that the use of the “deception test” is not appropriate in trial until it has been “sufficiently established to have gained general acceptance in the particular field in which it belongs.”

Nearly a century later, “general acceptance” for the use of the polygraph remains elusive. United States v Scheffer, a Supreme Court case argued in 1997, upheld military rule of evidence 707, which bars polygraph test results as sufficient evidence in military-related court cases. In the majority opinion, Justice Clarence Thomas reaffirms that “to this day, the scientific community remains extremely polarized about the reliability of polygraph techniques.” In practice, this means the polygraph will continue to hold a very limited place in court cases, with many state and circuit courts permitting its evidence only if both parties consent, and have strict admissibility requirements as expert testimony.

Polygraph Examinations for Federal Employment

Despite their inability to conclusively solve court cases, polygraph examinations continued throughout the 20th century. For instance, the frequent use of the polygraph by the federal government in the 1960s for screening purposes and criminal investigations (around 20,000 polygraph exams in 1963 alone) prompted a greater interest and investigation into the machine by Congress. Department of Defense directive 5210.48, first issued in 1965 and revised in 1984, sought to regulate polygraph use to a greater degree, establishing more concrete testing procedures, and explicitly noting that “polygraph examinations shall be considered as supplementary to, not as a substitute for, other forms of investigation that may be required under the circumstances.”

Following a dip in polygraph use during the 1970s, the 1980s brought a renewed interest in and use of the device on the federal level. In response to leaks of classified information, during President Ronald Reagan‘s first term, the White House issued National Security decision directive 84 in 1983. This directive required certain federal employees to undergo a polygraph test during investigations of internal leaks. Three years later, the Department of Defense Authorization Act of 1986 broadened this directive by prescribing a program of polygraph examinations beyond their previous limited use in extreme circumstances of classified information leaks.

The wider authorization of polygraph examinations in federal agencies was challenged and criticized by many who felt that the examination was both an invasion of privacy and scientifically unproven. The House of Representatives introduced a bill in 1984 titled Federal Polygraph Limitation and Anti-Censorship Act to challenge Reagan’s directive, and congressional agencies, such as the Office of Technology Assessment, were directed to conduct research reviews and evaluations of the accuracy of the polygraph. Reagan also received criticism from his own Secretary of State, George Shultz, who was excused from taking a polygraph examination after threatening to resign rather than take the test.

With the increasing push-back against polygraph examinations came the passage of the Employee Polygraph Protection Act of 1988. This act prohibits employers from requiring polygraph examinations for its employees or job applicants, putting a halt on the approximately one million polygraph examinations that were occurring in the US annually for employment purposes between 1981 and 1988. Notably, this act exempts local, state, and federal governments, as well as businesses that provide security services and manage controlled substances. For these exemptions, guidance is provided as to how a polygraph test should be properly conducted, as well as measures of qualification for the examiner.

Although a 2002 review by the National Research Council of the National Academies of Sciences, Engineering and Medicine (requested by the Department of Energy) advised the federal government against using polygraph examinations due to the lack of scientific evidence supporting the test, the American Polygraph Association says that a properly performed polygraph test has a high accuracy rate of over 90%. Many government agencies continue to use polygraphs for screenings and investigative purposes today, with the FBI requiring all applicants to pass a polygraph exam as part of the employment process.

Think I’m lying? Feel free to check out these additional resources on the polygraph yourself:

American Polygraph Association, Frequently Asked Questions.

Federation of American Scientists, Polygraph Policy Index.

The US Department of Justice Archives, Polygraphs at Trial.

Larson, John A. (1932). Lying and its Detection; a study of deception and deception tests.

US Government Printing Office (1986). Federal Polygraph Limitation and Anti-Censorship Act.

Synnott, John (2015). A Review of the Polygraph: history, methodology and current status. Crime Psychology Review, 1(1), 59-83.

Subscribe to In Custodia Legis – it’s free! – to receive interesting posts drawn from the Law Library of Congress’s vast collections and our staff’s expertise in U.S., foreign, and international law.