The Truth About Polygraphs

As everyone knows, there's already a "lie detector" in widespread use today?the polygraph. Police departments, government agencies, prosecutors, and defense lawyers regularly employ the device. The FBI uses it both to screen potential recruits and to intimidate suspects into confessing their crimes. Sex offenders, including those in California, also are regularly given polygraph tests during treatment and supervision.

And yet almost nowhere in the country do state courts admit polygraph results as evidence, except by stipulation (the lone exception is New Mexico). Moreover, California legislators felt strongly enough about the issue to pass a statute in 1983 that expressly prohibits the admission of polygraph evidence in criminal cases unless the parties agree otherwise. That law?Evidence Code section 351.1?was prompted by a court of appeal opinion the previous year that criticized the "almost 'knee jerk' " rejection of polygraph test results by judges (Witherspoon v. Superior Court, 133 Cal. App. 3d 24 (1982)).

Even proponents of the polygraph are quick to concede that the machine is not a true lie detector but rather a device that measures a person's physiological reactions to questions and answers by monitoring skin conductance, perspiration, blood pressure, and breathing patterns. Meanwhile, the accuracy of the polygraph continues to be a subject of rancorous debate.

It's common for professional polygraph examiners to claim accuracy rates higher than 90 percent to their paying customers, and the American Polygraph Association cites studies showing that polygraph accuracy rates are as high as 98 percent under controlled conditions. But a 2003 report published by the National Academy of Sciences concluded that the majority of polygraph research was unreliable and unscientific, and that "its accuracy in distinguishing actual or potential security violators from innocent test takers is insufficient to justify reliance on its use in employee security screening in federal agencies."

In the 1980s serial killer Gary Ridgway, also known as the Green River Killer, was among the dangerous liars who managed to pass a polygraph with flying colors. And Aldrich Ames, the CIA employee who spied for the Soviet Union, convinced three different polygraph examiners of his innocence before being arrested.

Almost everyone seems to agree that a crucial factor affecting the accuracy of a polygraph test is the skill of the examiner. However, that's not necessarily good news if you happen to be shopping for one in California. As in 20 other states, California doesn't even require polygraph examiners to hold a state license to practice their craft. That makes the Golden State something of a polygraph wild west: Basically, anyone can buy equipment and set up a truth shop in California.

"The way they regulate polygraph examiners in California is absolutely ridiculous," says Beverly Hillsbased Jack Trimarco, a former FBI agent who's considered one of the nation's top polygraph examiners. Trimarco has conducted close to 3,000 polygraph tests around the world, and he has participated in investigations of such high-profile cases as the Oklahoma City bombing and the Unabomber murders. "You could buy a polygraph machine tomorrow and claim to be a polygraph examiner," he says. "All you need is a computerized or analog polygraph, and you can just kind of fake it. We have guys out there right now who are just faking it. They have no idea what a polygraph is. But they're charging people. We need licensing and state oversight. Otherwise, you're going to have people out there with Ouija Boards and crystal balls."

In his practice, Trimarco has a loyal following among Southern California defense lawyers who bring him their clients in the hope of obtaining favorable polygraph results. If a test indicates the client is telling the truth, the attorney will sometimes approach a DA or prosecutor with the information. Although no case is won on the strength of a polygraph alone, some DAs are happy to drop a dog of a case when presented with the results of a polygraph test conducted by someone with Trimarco's credentials that works in the defendant's favor.

"I'm going down to San Diego next week to do a polygraph test on a murder case," Trimarco says. "The attorneys believe their client didn't do it, that it just looks suspicious because of time and circumstance. We'll see. I'd say three out of five subjects, sometimes four out of five, fail the test. It's that one out of five, though, that really makes my day."

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