1. What is a polygraph? A polygraph is a machine that measures several biological functions such as heart and respiratory rates to measure a person’s anxiety in response to a question. The theory is that a person’s biological reaction differs between truthful and deceptive responses to questions.

2. When do employers use polygraphs? Some public employers such as law enforcement agencies use them to conduct background tests in the hiring process. Other employers use polygraphs when conducting internal investigations into embezzlement and other frauds. Polygraphs should be viewed as an aid to be used in an investigation. Often, the stress of knowing that a polygraph is being used is enough for a suspect to yield a confession, though an employer should not threaten to take a polygraph test for this purpose.

3. Are “lie detectors” accurate? Not 100 percent. Administering a polygraph is an art, not a science. Two expert polygraphists may reach different results depending on how they approach the test. Much of the effectiveness of a polygraph is a function of the pre-testing interview of the suspect, the phrasing of the questions and the interpretation of the results. There are many examples of liars passing, truthful people failing, and test results coming back as “inconclusive.”

4. What is the best way to retain a polygraph examiner? It is often best to hire legal counsel to conduct the internal investigation and let the lawyer hire the examiner. There are two reasons for this: first, by the lawyer handling the investigation, the communications are covered by the attorney-client privilege, which will maintain confidentiality and help to protect the company from subsequent litigation, and second, a lawyer who has a working relationship with various polygraph examiners is in a solid position to select the best examiner for a given investigation.