1890s: Italian criminologist Cesare Lombroso discovers that blood pressure increases following

1890s: Italian criminologist Cesare Lombroso discovers that blood pressure increases following deceptive responses and develops the principles behind polygraph testing.

1915: Harvard psychologist William Marston devises an instrument to monitor the blood pressure of a subject under interrogation.

1921: Medical student John Larson develops the first true polygraph, adding a measure of breathing along with blood pressure.

1923: In its Frye vs. United States decison, the U.S. Supreme Court upholds the trial court’s exclusion of exculpatory evidence from a crude precursor to the modern polygraph in the case of a convicted murderer, finding the test unreliable because it wasn’t accepted by the scientific community.

1930s: Leonarde Keeler creates a polygraph instrument that remains in use today by integrating Larson’s instrument with measurement of electrical skin conductivity into a single machine.

1966: The Chattanooga, Tenn.-based American Polygraph Association is founded, which today represents more than 3,200 polygraph examiners in private business, law enforcement and government, sets educational and professional conduct standards for its members and accredits polygraph schools.

1978: In a decision that still applies today, the Ohio Supreme Court rules in State vs. Souel that polygraph tests are admissible as evidence in criminal matters in state courts only in cases where the prosecution and defense agree to their admissibility.

1988: Congress passes the Employee Polygraph Protection Act, which bars employment-related polygraph testing, with limited exceptions to the ban for fields such as law enforcement and the nuclear power and pharmaceutical industries.

1998: In United States vs. Scheffer, the U.S. Supreme Court gives state and federal officials broad discretion in determining polygraph admissibility.

2002: The National Academy of Sciences finds polygraph results reliable (consistent upon repetition), but not valid because they are highly prone to false positives (findings that the examinee is deceptive when he or she is actually truthful.)

Sources: Criminal Justice, 2006; Encyclopedia of Law Enforcement, 2005; Encyclopedia of Science,
Technology and Ethics, 2005; World of Criminal Justice, 2002; the American Polygraph Association Web site, www.polygraph,org;
and Atty. Dennis DiMartino of Boardman