Answering Your Frequently Asked Questions About Polygraph

A lot of what people know about polygraph comes from the movies, and it isn’t always completely accurate. Let’s explore the answers to some of the most frequently asked questions about lie detectors in the real world!

What is a Polygraph?

Polygraph examinations gather a selected group of physiological responses simultaneously. The equipment used can vary, but at least three sources of data will be collected. Respiratory activity is measured using sensors placed around the chest and abdomen. Sensors placed on the fingers help record sweat levels, and a device such as a blood pressure cuff will monitor cardiovascular activity. These are the key measurements most polygraph examiners will use, although others may be added. The data gathered during a session can be used to determine if the subject is telling the truth. Although often referred to as a lie detector, that isn’t accurate as a Polygraph measures changes in physiology which can indicate that a person is lying.

Who Uses Polygraph Exams?

Polygraphs are used for a number of different reasons. Most commonly, they are used by law enforcement agencies, government agencies, and the legal community. However, some companies and corporations can also use them as long as they abide by certain restrictions. It is also increasingly common for private individuals to book polygraph exams for non-criminal matters such as proving infidelity or settling other personal disputes.

What Does the Employee Polygraph Protection Act (EPPA) Cover?

The Employee Polygraph Protection Act of 1988 (EPPA) means that most employers cannot use a polygraph to pre-screen potential employees or as part of disciplinary proceedings. There are exceptions for a limited number of industries, including security services, pharmaceutical industries, and government agencies. Polygraphs can be used in the event of theft or embezzlement but must be conducted in accordance with strict regulations.

Who Has Access to Polygraph Results?

Only the authorized recipient can have access to the results of a polygraph test. As standard, this will include the examiner, the test subject, and anyone designated in writing and agreed to by the subject. This could be a spouse, employer, lawyer, or government official.

Is There Licensing or Legislation For Polygraphs?

There is no nationwide licensing requirement when it comes to polygraph. Still, many states and localities do have laws in place that require licensing, or at the very least certification for all polygraph examiners. This usually requires the polygraph examiner to have some type of formal training and a licensing exam. When it comes to Polygraph in Tennessee, licensing is necessary via The Private Investigation and Polygraph Commission.

Uncover the truth!


Ken Shull served as a Special Agent with the FBI for almost 25 years and was head of the FBI Polygraph program until his retirement in 2001. At that time he set up the Kendall Investigations practice as a private investigator in Knoxville, TN offering Polygraph services, private investigations, and security guards. Ken is a member of the American Polygraph Association and The American Association of Police Polygraphists.

The Truth is Still the Truth Even if No One Believes it, A Lie is Still a Lie Even if Everyone Believes it.