Moment of truth as lie detector's worth comes into question
By Julian Coman, in Washington
One of America's most famous detection devices may be consigned to the scrapheap after being used in thousands of trials and making countless appearances in Hollywood films.
The lie-detector, or polygraph test, is routinely used by United States police forces, the FBI, the Pentagon and other government departments in order to investigate crimes, screen employees and root out spies.
O J Simpson failed one after being accused of murdering his wife. In the recent hit film, Meet the Parents, Robert De Niro played an ex-CIA man who even subjects a prospective son-in-law to a polygraph test to discover his true intentions.
A government-sponsored study by the American Academy of Sciences concludes, however, that the suspicious father was wasting his time.
Two years of research has led the academy to report that the lie-detector, which measures abnormal blood pressure, breathing and skin response during interrogation, is so inaccurate and vague that it actually constitutes a "danger to national security".
Drew Richardson, a former FBI special agent and consultant to the report, said: "Panel members very clearly and emphatically found that no spy has ever been caught as a result of a polygraph.
"None would ever be expected to be revealed and large numbers of the tens of thousands of people subjected yearly to this sort of testing are probably being falsely accused about their backgrounds and activities."
Dr Stephen Fienberg, a computer scientist who headed the academy panel that produced the report, said: "The deep flaws with the lie-detector are to do with the thresholds set by interrogators."
The panel found that to catch eight out of 10 spies, an estimated 1,600 innocent interviewees would also be placed under suspicion, rendering the results meaningless.
Eliminating the so-called "false positives" would mean that almost no genuine targets would ever be caught.
"National security is too important to be left to such a blunt instrument," said Dr Fienberg.
"There is a mystique about the lie-detector that very much needs to be addressed. It has led to an overconfidence about the status of its results in the popular mind.
"The idea of something that infallibly discovers the truth has been seductive for centuries. We used to use hot coals and irons."
The Los Angeles Police Department, which is currently suffering a chronic shortage of staff, has given a polygraph test to more than 2,000 selected recruits this year.
Only half those interrogated were judged to have passed. The rest were deemed to have lied about drug use and other matters of "personal integrity".
The Pentagon gives lie-detector tests to 73.6 per cent of employees as "a condition of access to certain positions or information".
The study will be discussed by the US Congress early next year.
It was commissioned by the Department of Energy after a humiliating fiasco involving an employee at the sensitive Los Alamos nuclear research laboratory in New Mexico.
On the basis of a series of polygraph tests, Wen Ho Lee, an experienced scientist at Los Alamos, was accused in 1999 of passing nuclear secrets to China. He was later exonerated of all spying charges.
There was further embarrassment for the advocates of lie-detectors last year when Ana B Montes, the Pentagon's senior Cuba analyst, confessed to a 16-year spying career for Fidel Castro. She had easily passed obligatory polygraph examinations before taking on her job.
The report's authors are now lobbying congressmen and senators for a gradual phasing out of the technology. A decision on the future of the lie-detector will be taken next year.
So far, however, Mr Fienberg's conclusions are being fiercely resisted, particularly by police departments.
At the Pentagon, Lt-Col Ken McLellan said there were no immediate plans to abolish polygraph tests, but admitted that alternatives were being considered.
"We've been doing research into voice tremor technology, but we haven't really had much success with that," he said.
"However, new infra-red technology that measures the heat on a person's face does seem promising. In the end we're just interested in getting people to tell the truth."