Why are polygraph test results not used in court or in a criminal investigation?
Polygraph tests are used in ivestigations, the results or any information learned are not acceptable as evidence in criminal court cases. The results are sometimes used in lower level civil cases. Sometimes,when the judge is the one making the decision, they can be used with other evidence in impeaching the tesimony of a witness ( proving that a witness is unreliable, or an out and out liar) or in the sentencing portion of a trial. “Lie detector” results are not acceptable because they are not reliable the machines essentially measure physiological changes, heart rate, breathing rate, sweat on the skin and such. Some people can control those changes, congenital or experienced liars may not even have those changes, a person who is just mistaken and thinks he is telling the truth will not show changes. Conversly a persons health will effect the results as will his mental state, a nervous or frightened person will show changes. The results also are influenced by the person giving and inte
