The Introduction of Polygraphs or other Lie Detector Tests at Trial and Other Uses of the Polygraph

Generally, courts in most jurisdictions do not admit the results of polygraph or other lie detector examinations. Most courts find such results quite unreliable and untrustworthy. There are a number of states that will admit polygraph or lie detector tests results into evidence if both the prosecution and defendant agree that the test results will be admitted.

Arguments Against Admissibility of Test Results

If the defendant is being tried in a jurisdiction that admits lie detector test results, the prosecution will generally argue against the admissibility of the results. First, the prosecution may argue that the results of the test are unreliable. Second, the prosecution may argue that the test was not properly administered. Third, the prosecution may argue that even if the test was properly administered the results would not assist the trier of fact. Fourth, the prosecution may argue that the results are inadmissible under the rules of evidence. Lie detector test results are not admissible under most state rules of evidence and under the federal rules of evidence. Last, the prosecution may argue that the lie detector test results are inadmissible unless the credibility of the witness whose results are sought to be admitted has been attacked.

Typically, the prosecution is not required to disclose lie detector test results of a witness when the witness failed the test. Courts in various jurisdictions have found that the defendant's due process rights were not violated by the prosecution's failure to disclose such evidence when lie detector results were inadmissible.

Other Uses for the Polygraph Test

The Federal Bureau of Investigation (FBI) uses polygraph testing as part of their initial screening of candidates for the special agent selection program. The FBI also uses polygraphs as an investigative method for interrogation of suspects in certain crimes.

Often times criminal defense attorneys will ask their clients to take a polygraph examination prior to representing the defendant. The defendant is not required to take the test, but if they do not the attorney may choose not to represent the defendant.

Some employers also require the administration of a polygraph or lie detector examination prior to extending a potential employee a position with the company.