Frequently Asked Questions


What is a Polygraph?

A polygraph is an analog or computerized instrument that measures selected physiological activities within the body. A polygraph instrument collects data from at least three systems in the human body including respiratory or breathing, blood pressure, and sweat gland activity. Convoluted rubber tubes are placed over the test subject's chest and abdominal area which record respiratory activity and two small metal plates are attached to the fingers to measure changes in sweat gland activity. A blood pressure cuff, or similar device is used to record cardiovascular or blood pressure activity.

A polygraph examination includes a pretest and testing period. During the pretest the examiner will complete required paperwork and talk with the test subject about the test. During the pretest period, the examiner will discuss the questions that will be asked and will familiarize the test subject with the testing procedure. During the testing or chart collection phase, the examiner will administer the selected test questions and will collect a number of polygraph charts. Only questions that have been discussed with the test subject will be asked.

Following the testing phase, the examiner will analyze the charts and render an opinion as to the truthfulness of the person taking the test, base on the responses measured by the polygraph instrument. The examiner will usually offer the test subject an opportunity to explain physiological responses in relation to one or more questions asked during the test. It is important to understand that a polygraph testing procedure does not include an analysis of the physiology associated with voice stress. Other type instruments that claim to record voice stress are not polygraphs and have not been shown to have scientific support like the polygraph.

Who Uses Polygraph Examinations?

Polygraph users include law enforcement agencies, the legal community, and the private sector. These segments of society include the following:

  • Law Enforcement Agencies - Federal Law Enforcement Agencies, State Law Enforcement Agencies, and Local Law Enforcement Agencies such as Police and Sheriff's Departments.
  • Legal Community - US. Attorney Offices, District Attorney Offices, Public Defender Offices, Defense Attorneys, Parole & Probation Departments.
  • Private Sector - Companies and Corporations under the restrictions and limitations of the Employee Polygraph Protection Act of 1988 (EPPA).
  • Private citizens in matters not involving the legal or criminal justice system.
  • Attorneys in civil litigation.

What Laws Govern the use of Polygraph Examinations?

The Employee Polygraph Protection Act of 1988 (EPPA) prohibits most private employers from using polygraph testing to screen applicants for employment. It does not affect public employers such as police agencies or other governmental institutions.

Who Gets the Test Results?

According to the various state licensing laws polygraph results can be released only to authorized persons. Generally those individuals who can receive test results are the test subject, and anyone specifically designated in writing by the test subject, the person, firm, corporation or governmental agency which requested the examination, and others as may be required by due process of law.


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