Lie Detector Test Law and Legal Definition

Lie detector test is a test which evaluates a person's physiological response to questions asked by a testing expert in order to determine if the person is telling the truth or lying. Such tests often include a polygraph and a voice stress analysis. In such tests, activities of the body that are not easily controlled by the conscious mind, for example changes in blood pressure, respiration and heart rate, are compared under different circumstances.

Critics claim that ‘lie detection’ by use of polygraphy does not have scientific validity because it is not a scientific procedure. The reliability of lie detection test is a matter of ongoing controversy. Most U.S. states do not admit such test results in court.

The following is an example of a state statute (Hawaii) defining the term:

According to HRS § 378-26, ‘Lie detector test’ means a test to detect deception or to verify the truth of statements through the use of any psychophysiological measuring device, such as, but not limited to, polygraph tests and voice stress analyzers.