Questioning the Polygraph.
The use of the polygraph is usually not accepted into evidence in a trial. However, it is common to use a polygraph when monitoring compliance of the rules of one’s of probation. It is generally accepted that polygraphs are far from foolproof. False positives or false negatives occur more often that one would think. Sanctions that are used with deceptive polygraphs usually draw support when the violation is supported with other evidence. (e.g., self admission by the client to a violation of probation).
When arguing against the results of a suspected deceptive polygraph, most clients will report that the test is in error and let it go at that. I am always surprised to see that almost all clients, and their attorney, fail to secure a second opinion. A second polygraph administrator might interpret the result differently. Additionally, support is usual made for the defense because most polygraph testers refuse to reveal or present their raw data. Failure to present that data should nullify any polygraph results. Without the polygraph, there can be no reason for sanctions for a clients.