The Polygraph Test - Does It Work?

Does the polygraph test, otherwise known as the lie detector test, work? Melvin Foster may not think so. Back in 1982, after profilers thought a taxi driver might be the Green River Killer, they targeted Foster as a suspect, partly because he drove a taxi. He generously agreed to a polygraph test, which he failed.

The problem was, he was innocent.

Meanwhile, over a period of about two to three years, the Green River Killer murdered four dozen or more women near Seattle and Tacoma, Washington. During this time, Gary Leon Ridgway was briefly a suspect, and he was given a polygraph test. The test, done in 1984, determined that he was telling the truth about his innocence. He was free to keep killing, and he did.

It wasn't until 2001 that DNA evidence (and other evidence) proved Ridgway was the killer. In 2003 he confessed and pleaded guilty to 48 of the murders. Melvin Foster was finally cleared after more than 20 years.

The police never could gather enough evidence to arrest or prosecute Foster (difficult when the suspect is innocent). But unfortunately, Foster was under a cloud of suspicion the entire time. According to an article in the King County Journal, in 2003, Foster asked the King County Sheriff's Office to finally "apologize and return his rock tumbler and all the rest of the stuff police took from his home in 1982."

It would be nice to think that this doesn't happen often, but how do we know? There are certainly many other stories about innocent people pointed at as guilty due to a failed polygraph test, but those are just the ones where the truth comes out. Had Ridgway not been caught, many would still think Melvin Foster was guilty.

How many other cases are left like that, with a cloud of suspicion over an innocent man or woman? What do people think when you fail a polygraph test? They think you are guilty, of course. But what about the more common "inconclusive" result. Well, you didn't pass, so you must be guilty or know something, right? Isn't that what we really think when a criminal suspect or "person of interest" in the news can't pass the test?

Do you think the test at least points out the real criminals along with few innocent people it wrongly labels? Think again. Consider the fact that numerous famous spies passed the polygraph tests they were given (Ignatz Theodor Griebl, Karel Frantisek Koecher, and Jiri Pasovsky, among others). Also consider the fact that many hardened criminals have proven their ability to lie and still pass the test.

"The US is, so far as I know, the only nation which places such extensive reliance on the polygraph....It has gotten us into a lot of trouble." - Convicted spy (double-agent) Aldrich Ames, who passed two polygraph tests while spying for the Soviet Union.

Most scientists think there is no scientific basis for the polygraph. It is junk science. Of course, any lie detecting technique which points at enough possible liars will identify some of them. But what if you are telling the truth? The bottom line is that you're gambling with your reputation if you rely on the polygraph test to prove your innocence.