Is it true that lie detector tests are not admissible evidence?
The prevailing rule is that results of a polygraph are not admissible on the issue of credibility. Such a rule would jeopardize a suspects civil rights and presumption of innocence if the jury placed too much emphasis on the test results, which are subject to error.
However, contrary to what you may see on television or at the movies, the fact that a criminal suspect took a polygraph is not per se barred from trial. In fact, a federal appellate court recently allowed the government to introduce evidence of a polygraph exam at a criminal trial.
In United States v. Tenorio, the Tenth Circuit was asked whether it was improper to admit evidence of a polygraph exam where the criminal defendant claimed that his confession was coerced.
In concluding evidence of the test was admissible, the court held that the criminal defendant “opened the door” to admission of the test by affirmatively representing that the government had obtained his confession through improper means.
The decision joins several other federal courts of appeals that hold “when the defendant opens the door to polygraph evidence, such as attacking the nature of a criminal investigation or asserting that testimony was coerced, polygraph evidence is admissible rebuttal evidence.”
While evidence of the polygraph was admissible to rebut the claims of coercion, the court continued to exclude results of the exam, which it held were more prejudicial than probative on the issue of credibility.
If you have questions about police-citizen encounters, or what to do when confronted by police, contact the attorneys at Bryan & Terrill Law, 918-935-2777.