THE NATIONAL ACADEMY OF SCIENCES says that lie detectors don’t work. But people still use them:

After a series of stormy public meetings in New Mexico, Congress mandated the testing of the 20,000 employees at both labs. But New Mexico senator Jeff Bingaman, for whom this was a constituent matter, forced into the bill the funding for the National Academy of Sciences report on the reliability of the polygraph when used for security screening. When it was released late last year, the study proved the most significant critique of the polygraph since the Frye decision.

The study determined that not only was the polygraph useless for security screening but that its use might actually be detrimental to the work of keeping the labs secure. It argued that the test was so vague that, to catch one spy, nearly 100 other employees might have to have their security clearances lifted. “Polygraph testing,” the report concluded, “yields an unacceptable choice . . . between too many loyal employees falsely judged deceptive and too many . . . threats left undetected.” . . .

“Why do we keep using it when we keep saying it’s not reliable?” asks Bingaman. “That’s an awfully good question. I think it just appeals to a lot of people’s faith that there’s a technological fix to every problem and, if you just get the right machine hooked up, you can determine all the right answers.”

It’s basically trial-by-ordeal with fancy printouts, and about as accurate. My own sense is that when somebody proposes a polygraph test, then either he’s ignorant, or he thinks that you are.

UPDATE: A slightly disturbed reader emails:

Next thing you know, you’ll want to deny me Benefit of Clergy. You are a damned communist, Glenn.

Do you know the “neck verse?” Anyway, I sentence him to the Ordeal of the Accursed Morsel, quite a few of which are available from the cafeteria downstairs. . . .

YET ANOTHER UPDATE: What’s the “neck verse?” email a couple of readers. Ah, you may well ask. (“I am asking!” “And well you may!”) It’s here. I couldn’t find a reference to the “ordeal of the accursed morsel” online. (Yes, not everything is on the Web, you know.) If I recall correctly, a priest said some words over a piece of dry bread that was then fed to the accused. If he choked he was deemed guilty. This was a sort of primitive lie detector, in that nervous people often have dry mouths. Of course, when you find yourself before Theodoric of York, Medieval Judge, you ought to be nervous, regardless of guilt or innocence. And that’s the problem with lie detectors, too. As soon as someone gives you a lie detector test, you know your fate is in the hands of either idiots or charlatans, which should make anyone nervous.