Accuracy

• Since its invention in 1923, the accuracy of the polygraph has been suspect. As reported by the Electronic Privacy Information Center, a 2002 study by the National Academy of Science found that the accuracy of the polygraph is questionable, at best, because physiological measures are variable and can be altered with the use of anxiety-reducing medication and common antidepressants.
  
  

Government Use

• Police officers and government agents conducting security clearances on employees are generally permitted to use polygraph tests for internal reasons. For purposes of probation or parole, many states require sex offenders to regularly submit to polygraph tests.
  
  

Private Party Use

• The Employee Polygraph Protection Act (EPPA), passed in 1988, prohibits the firing of employees based on the polygraph test. An employee can refuse to take the test or terminate the test at any time. The employer cannot reveal the results of the test to any third parties.
  
  

Admissibility

• Polygraph tests are not admissible in the federal courts. United States v. Sheffer, in 1998, reaffirmed that the polygraph cannot be admitted because its accuracy continues to be contested in the scientific community, with some tests rating accuracy as high as 87 percent and others as low as 50 percent.