chapter  8
6 Pages

Polygraph Examinations

The polygraph, commonly called the lie detector, is not really an investigative technique

in and of itself. It is actually a form of interview. The polygraph is a mechanical device

designed to detect physiological changes that occur when a person makes an untruthful

statement. While many people firmly support the accuracy of the polygraph, the fact is

that it has little value as evidence in court. Indeed, only New Mexico routinely allows

polygraph examination results to be admitted in evidence in criminal trials. The U.S.

Supreme Court ruled in 1998 that a criminal defendant does not even have the right

to present evidence in his own defense that he has passed a polygraph test. Justice

Clarence Thomas ruled that there is “simply no consensus that polygraph evidence is

reliable.” He continued by stating that “to this day, the scientific community remains

extremely polarized” about the question.