Law enforcement considers them a useful investigative tool. But Congress banned their use in private industry in 1988. Critics of polygraph tests say they don't work. Defense attorney William G. Hundley watched as his client, implicated in the Koreagate scandal of the 1970s, took a lie detector test. Yet his client later confessed that he had lied throughout the test.
Polygraph examiners admit that the test can be beaten.
One has even estimated that 50 percent of the population could, through intensive training, learn how to beat the test. Yes, but not easily. When the poly is beaten, it's usually by training or by fluke. Some polygraph experts estimate that lie detector tests are accurate in 95 percent of all cases. But this figure is disputed and some estimate the range of accuracy as anywhere from 70 to 90 percent.