FAYETTEVILLE, N.C. — It is a tool of truth for investigators and defense attorneys, but not prosecutors. Laws restrict the use of polygraphs on employees and bans lie detectors from court. It may be futile, but it is perfectly legal to try to beat a polygraph.

After 25 years of polygraph testing, T.V. O'Malley, a Fayetteville private investigator and the vice president of the American Polygraph Assocation, preaches the science of truth.

"If that test indicates this person is being truthful, I don't care what it is. I believe that person is being truthful," O'Malley said.

However, O'Malley's profession comes under constant fire from disbelievers. Critics call it "junk science" that is not admissable in North Carolina courtrooms.

Polygraph critics contend there are plenty of ways to beat the test -- from breathing techniques to mind games such as focusing on math calculations.

"What they can teach this person to do at best is to come up with an inconclusive test," O'Malley said.

Another theory is to confuse the test with pain. Sometimes, when people try to bite their lip, the polygraph detects deception. No matter what people try, O'Malley said it is not illegal to try to beat the polygraph.

Wake County Sheriff Donnie Harrison said lie detector tests can make suspects cave on crimes.

"Everybody's got their own theories about how to beat something, but it goes back to the science. You're not going to beat it," Harrison said.

O'Malley believes with improvements in technology and tighter standards on licensing, polygraphs will eventually be allowed back in court. He does believe a small number of unscrupulous examiners still hurt the polygraph industry.