No test based on the polygraph can distinguish truth from deception with high validity, and it is unlikely that a trustworthy lie detector will ever be invented. Further, there are no behavioral cues an experienced observer could use that would be of such accuracy that courts, employers, and others could defer to purported 'expert' judgment. The increasing trend toward the use of the polygraph in criminal justice and personnel decisionmaking in government and private business has occurred in the absence of any reliable evidence that the data produced gives accurate information about the subject. Truth technology must be regarded as a growing menace in American life, a trend to be resisted by legislation and public outcry. Ways to beat the polygraph include self-induced techniques that can affect the bodily functions measured by the polygraph. Finally, the Guilty Knowledge Test is a promising criminal investigation tool that can be used as an alternative to the traditional polygraph test.