Ever since the inception of polygraph (lie detector) tests there has been considerable disagreement regarding its validity. Even in the face of conflicting scientific field studies, advocates of the system still claim a 90-100 percent accuracy rate. Moreover, polygraph has little validity with scientists. Currently there is no scientific field evidence that polygraph tests can be used effectively as a valid test in criminal investigations or to prescreen employees. A 1997 survey of 421 psychologists estimated the accuracy of a polygraph to be at approximately 61 percent, which is slightly better than chance. Even so, law enforcement agencies across the nation are devoted proponents of this unscientific device; even the American public, at large, seems to believe in its validity as well.
At the turn of the century, polygraph was given another try by the scientific community. Ten popular field studies were done to test the validity of polygraph once again, which included a survey done for purposes of applicant screening and security clearances for employees using the polygraph. With these studies, scientists were trying to answer vital questions about its scientific validly. The answer to the first question—are polygraph examinations valid?—provided results that polygraph examinations detected deceptiveness and nondeceptiveness better than chance, but some cases also showed a high error rate, particularly in nondeceptive subjects. Scientists also found that there was a great deal of variability in the results. For instance, results for correct innocent detections ranged from as low as 12.5 percent to as high as 94.1 percent; or results for false positives ranged from 75 percent to zero percent in two studies.
Although many of these tests indicate that polygraph testing is better than chance at differentiating deception from nondeception, there is also enough scientific proof to hold this system as unscientifically proven. Scientific analysis puts the error rate of the polygraph between 10 and 25 percent, which means that a large number of incorrect decisions would be made if the lie detector was widely in use. Furthermore, in United States v. Scheffer (1998), the Supreme Court [majority] stated, “There is simply no consensus that polygraph evidence is reliable: The scientific community and the state and federal courts are extremely polarized on the matter”. So clearly, if the Supreme Court holds this position on the polygraph, why should it then be used in the private sector or criminal justice system to prescreen employees? It shouldn’t.