Legal Definitions - lie detector test

Lie Detector Test

A lie detector test, most commonly known as a polygraph, is a procedure that attempts to determine if a person is being truthful by measuring their involuntary physical responses while they answer questions. These responses can include changes in heart rate, blood pressure, breathing patterns, and skin conductivity (which indicates perspiration).

The underlying theory is that a person's body will react differently when they are being dishonest compared to when they are telling the truth, due to the stress or anxiety associated with deception. However, this is why the term "lie detector" is somewhat misleading; the test doesn't directly detect lies, but rather measures physiological signs that might be associated with stress, fear, or anxiety, which could arise from either lying or simply being nervous about the test itself.

The scientific validity and reliability of lie detector tests are highly controversial. Experts widely agree that these tests are not accurate enough to reliably distinguish between truth and deception. Factors like general anxiety, medical conditions, or even deliberate countermeasures can significantly affect the results, making them unreliable. Consequently, in most legal proceedings, including both federal and state courts, the results of a lie detector test are generally inadmissible as evidence during a trial. This means a jury or judge typically cannot consider polygraph results when deciding a case, even if a defendant wishes to present them.

Despite their inadmissibility in court, lie detector tests are sometimes used in other contexts. Law enforcement agencies might use them during criminal investigations to gather information or encourage confessions, though any confession obtained must still be voluntary and legally sound. Additionally, certain government agencies, particularly those involved in national security, may require polygraph examinations as part of their personnel screening process for sensitive positions.

In the private sector, federal and most state laws prohibit employers from requiring employees or job applicants to take a lie detector test. There are limited exceptions, such as for investigations into specific economic losses like embezzlement, but even then, strict regulations apply to protect employee rights.

Examples:

• Criminal Investigation: During an investigation into a series of burglaries, detectives ask a person of interest, Mr. Henderson, if he would be willing to take a polygraph test. The detectives explain that while the results cannot be used as evidence in court, it could help them narrow down suspects and potentially clear his name. Mr. Henderson agrees, hoping to demonstrate his innocence. Even if the polygraph administrator concludes Mr. Henderson was deceptive, this result alone cannot be presented to a jury if he is later charged and goes to trial. However, the police might use the results to inform further investigative steps or to pressure Mr. Henderson during questioning.

  This example illustrates how lie detector tests are used as an investigative tool by law enforcement, not as definitive proof of guilt or innocence, and highlights their general inadmissibility in court.

• Government Employment Screening: Ms. Chen applies for a high-level position with a federal intelligence agency that requires access to classified information. As part of the extensive background check and security clearance process, she is informed that she must undergo a polygraph examination. During the test, she is asked questions about her past activities, foreign contacts, and loyalty to the United States. The agency uses the polygraph results, alongside other investigative findings, to assess her trustworthiness and suitability for a role involving national security, which is one of the permitted uses for such tests.

  This example demonstrates a specific context where lie detector tests are legally permitted and commonly used: for government employment, especially in national security roles, due to the sensitive nature of the work.

• Prohibited Private Sector Employment Use: After a significant amount of cash goes missing from the company safe, the owner of a small retail store, "Bargain Bin," demands that all employees take a lie detector test to identify the culprit. One employee, Sarah, feels pressured but refuses, citing her legal rights. The owner threatens to fire her if she doesn't comply. Sarah consults an attorney and learns that, in most private sector employment situations, it is illegal for an employer to require a lie detector test or to take adverse action against an employee for refusing one, unless specific, narrow exceptions apply (which are usually not met in a general theft scenario like this).

  This example illustrates the legal restrictions on private employers regarding lie detector tests, showing that they generally cannot compel employees to take them or penalize them for refusal, protecting employees from unreliable testing methods.