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Jan
04

Polygraph Admissibility Revisited

Polygraph examination admissibilityIn 1993, the Supreme Court held that “certain Federal Rules of Evidence should govern the admissibility of scientific evidence and required the judge to make a preliminary assessment of the relevance and reliability of the evidence1.
Admissibility of polygraph examinations depends on the given situation. For example, in a revocation hearing, the standard proof is  NOT ‘beyond a reasonable doubt’ required at a criminal trial, but “a preponderance of the evidence”. Probation and parole are usually considered privileges, not rights, so polygraph results are sometimes provided to the court or parole authorities to help with reach a more educated decision.

State statutes vary regarding the admissibility of polygraph information as evidence in a court of law. These concerns tend to fall into the following categories:

  1. The lack of agreement about whether polygraph examinations are scientifically valid;
  2. The lack of a definitive error rate;
  3. The lack of controlling standards of practice in the polygraph profession; and
  4. Questions about juries giving polygraph findings excessive weight in the decision- making process and weakening their role as determiners of truth.

Scientifically Valid & Accurate

The American Polygraph Association’s web site documents 2,174 field examinations with an average accuracy of 98%.  You can read more about this at http://thepolygraphexaminer.com/blog/polygraph-exam-accuracy/

Examination Standards

As with any industry, it is unavoidable and unfortunate that there are entities that don’t adhere to professional standards. A way to avoid this is to only utilize polygraph examiners that are certified and adhere to the APA standards. The American Polygraph Association By-Laws require that all conclusions and opinions be based on a quantitative or numerical scoring
system for all evidentiary examinations.  They have also published standards of practice for examiners conducting examinations, and these standards are intended to limit variation in practice across examiners.

Juries & Findings

The last concern with polygraph examination admissibility is the fact that juries or courts will give TOO MUCH weight to results obtained from a polygraph test, either positive or negative. While accurate, polygraphs are tools to uncover an underlying baseline truth. They are just one more piece of the puzzle. The mere fact of someone agreeing to take a polygraph often speaks volumes. Many times, the polygraph is used as a pre-trial tool to avoid court altogether. It is up to the attorneys involved to put the polygraph findings and it usage in the proper perspective for the court.

Opening Doors

The Daubert v. Merrell Dow Pharmaceuticals, Inc. case, mentioned in the first paragraph,  creates a possibility for the admissibility of polygraph data. It would allow district courts the authority to determine if evidence is relevant and reliable.

A good example, in appeal of the Kansas v. Lumley2 case, the defendant appealed a prison sentence that resulted from his untruthful answer to a polygraph question, the judge found that polygraph reliability was sufficiently robust to be acceptable. This would apply to a parole or probation revocation hearing that requires a lesser standard of proof than a finding of guilt. Further, the judge indicated that without the polygraph examinations and the admission of the results as a condition of probation, the sex offender  supervision program could not be maintained.


If you would like to discuss the professional services of a polygraph examiner, please contact The Polygraph Examiner at 1-800-497-9305.

  1. Daubert v. Merrell Dow Pharmaceuticals, Inc. [509 U.S. 579, 1993] []
  2. WL 218704, 1999 []