Polygraph tests don’t detect lies, says criminologist


PETALING JAYA: A criminologist contends that polygraph (“lie detector”) tests should not be admissible in court because of its controversial and unreliable nature.

“Many nations have not allowed the findings of the polygraph test to be used as evidence in court,” says P Sundramoorthy of Universiti Sains Malaysia.

He told FMT that polygraph tests have no actual way of quantifying deception and only measure certain signs that a person may be deceiving.

Instead of turning to polygraph tests, he suggested that priority be given to physical evidence such as DNA tests and CCTV recordings, eyewitness testimonies, motives and thoroughly written investigation reports.

“At the most, polygraph test results can be generally used as one of the many tools for the investigation of criminal cases and to assist law enforcement officials in the process of investigation,” he told FMT.

He had been asked for his views on the judiciary’s move to study the possibility of using these test results as evidence. Sundramoorthy said he agreed with the Chief Justice Tengku Maimun Tuan Mat’s call to study the possibility of the polygraph test as it involves amendments to the law.

Sundramoorthy said polygraph tests were based on measuring heart rate, blood pressure, breathing and sweating, as factors to detect deception.

“There are no unique physiological signs of deception,” he said.

“Lets us not go primitive in pushing for this implementation. We cannot send the innocent to prison just because of the findings from an instrument considered to be unreliable and untrustworthy.”

This article first appeared on FMT.

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