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No Lie, Polygraphs Don't Offer Concrete Evidence
Evidence Experts Can Interpret Test Results Differently

By Michael Stroh
The Dallas Morning News

When physicist Wen Ho Lee first denied leaking U.S. nuclear secrets to the Chinese, authorities from the Department of Energy in 1998 wired him to a polygraph to see whether he was lying.

The Los Alamos National Laboratory scientist passed. But later when a polygraph expert from the FBI looked at the same test results, he concluded that Dr. Lee had not told the truth.

How could the same lie detector test lead investigators to exactly opposite conclusions?

The case of physicist Wen Ho Lee, who eventually pleaded guilty to one felony count of mishandling classified information, has left law enforcement experts trying to answer the same fundamental questions that have existed since the invention of the lie detector 80 years ago: Does the polygraph actually work? And is it fair?

"It's reignited this smoldering controversy," says Steven Aftergood, a senior research analyst with the Federation of American Scientists in Washington.

In an essay being published in the journal Science, Mr. Aftergood argues that a new federal policy requiring nearly 20,000 employees of the national nuclear weapons laboratories to take lie detector tests is having undesirable effects.

The policy has lowered morale, Mr. Aftergood writes, caused some of the nation's most gifted scientists to leave and made it harder for the labs to recruit talented young researchers for the weapons programs. The use of the polygraph, he writes, "symbolizes the defeat of reason by the national security state."

Testing on the rise Despite such criticisms, the use of polygraph tests is on the rise. Congress banned private industry's use of lie detectors as a condition of employment in 1988, but they are routinely used for employee screening at the FBI, the Central Intelligence Agency, the National Security Agency and local police departments across the country. The percentage of law enforcement agencies using polygraphs for this purpose rose from 16 percent in 1962 to 62 percent in 1999, according to a survey by Michigan State University's School of Criminal Justice.

There's also a growing market for polygraphs outside law enforcement. The American Polygraph Association, the largest polygraph accrediting and licensing organization in the country, reports that its membership has risen to more than 2,000 and is continuing to grow.

Private polygraph examiners handle everything from fishing tournaments to divorce cases.

'Many writings' Lie detectors aren't designed to detect lies as much as the subtle physical changes that may occur when a person tells a lie. The word "polygraph" means "many writings," and that is what the polygraph machine produces: lots of squiggly lines on a scrolling piece of paper.

The test works like this: A subject is seated in a chair. Two rubber belts are wrapped around his chest and stomach to measure breathing patterns. A blood pressure cuff is wrapped around an arm. A metal plate attached to the fingers measures sweat gland activity.

The polygraph examiner then asks the person a series of questions. Some of the queries are "control" questions unrelated to the matter under investigation but which establish a base line of the person's blood pressure, respiration and perspiration. Other questions directly address the actions under scrutiny.

The examiner interprets the person's physiological response to each of the questions, as recorded on scrolling paper, to judge whether the person is lying. And thus the uncertainty about polygraph results: they are a matter of judgment. "There's no red light or siren that comes on when the person lies," says Milton O. "Skip" Webb, Jr., president of the American Polygraph Association.

But enough guilty people have slipped past polygraph tests to have given law enforcement officials pause. Most federal and state courts do not allow polygraph results to be entered as evidence.

Still, even critics of the tests acknowledge that they have led to admissions of guilt that they might not otherwise have gotten. "The polygraph itself functions as a prop more than anything else," Mr. Aftergood said. "Yet, there are cases every year in which the prop works."

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