Lie-Detector Tests: Junk Science?

By November 19, 2002Articles

Under California law, a private sector employer cannot require a polygraph, lie detector or similar test as a condition of employment or continued employment. Under Labor Code Section 432.2, a polygraph test cannot be used by an employer in the pre-employment screening or hiring process, without the express and voluntary consent of the job applicant. Similarly, an employer cannot compel employees to submit to a lie-detector test as part of an employer’s investigation of a work-related incident, such as sexual harassment.

Federal law also places a ban on use of lie-detector tests in the work-place but with some major exceptions. Under the Employee Polygraph Protection Act, the federal government, government contractors, security firms and drug companies are permitted to use polygraphs as a job applicant screening devices. These types of employers are also allowed under federal law to require employees submit to lie-detector tests while investigating incidents of theft, embezzlement, misappropriation of trade secrets, espionage and sabotage.

But recently, an in-depth study by the National Academy of Sciences declared polygraph examinations to be “dangerously unreliable”. The Academy strongly recommended the federal government to cease depending on polygraph results as a means of screening for security risks. Based on an 18 month study, the report concluded that conventional lie-detector tests not only incorrectly deem large numbers of people who are telling the truth to be liars, but may have also allowed spies (i.e. liars) into sensitive job positions because they were able to fool the test.

Because, many agencies such as the FBI and Department of Energy strongly rely on the use of polygraphs in the hiring process, the devices themselves create a security problem. Lie-detector technology is “badly outdated” the study concluded. Nevertheless, lie-detector tests are still widely used by the federal government and in criminal investigations. The study’s recommendation was for extensive research into prospective new lie-detection techniques such as brain activity analysis, voice-stress levels and thermal imaging.

For any questions or comments regarding this Labor Law Update please contact attorney Michael Daly of the Daly Law Firm at (619) 525-7000 or

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