Criminologists wary of polygraph tests as admissible court evidence but lawyers say up to judiciary

Public interest in the lie detection method emerged recently after Muhammad Yusoff Rawther underwent a four-hour lie detector test at Bukit Aman police headquarters after accusing PKR president Datuk Seri Anwar Ibrahim of sexual assault. — Picture by Miera Zulyana
Public interest in the lie detection method emerged recently after Muhammad Yusoff Rawther underwent a four-hour lie detector test at Bukit Aman police headquarters after accusing PKR president Datuk Seri Anwar Ibrahim of sexual assault. — Picture by Miera Zulyana

KUALA LUMPUR, Dec 21 — Criminologists and lawyers appear to be equally divided on the use of polygraph tests and its results as evidence in a court of law.

While crime experts are considering it unreliable, those from the legal fraternity feel it should be up to the judiciary and legislature to decide.

Commonly referred to as a lie detector test, polygraphs measure a person's physiological factors including blood pressure, pulse, and respiration while being asked questions. It is believed that when a person lies, their bodies will respond in a way that differs if they are telling the truth.

Public interest in the lie detection method emerged recently after Muhammad Yusoff Rawther underwent a four-hour lie detector test at Bukit Aman police headquarters after accusing PKR president Datuk Seri Anwar Ibrahim of sexual assault.

Universiti Sains Malaysia criminology associate Prof Datuk P. Sundramoorthy said one cannot rely on any type of machinery to determine truth from lies.

“At the most, the polygraph is used as one of many instruments to assist in preliminary investigations. Most countries around the world do not consider the results to be admissible in court. Even if the country allows it will not be used as the sole evidence in a case,” he told Malay Mail.

Sundramoorthy also pointed out that polygraphs also have glaring flaws, he said there is a chance for someone to be found lying during the preliminary investigation but after thorough investigations — it is concluded that he was telling the truth.

“The polygraph machine picks up on a person's nervousness or other similar issues. It is a very dangerous and primitive method of investigating. I think our learned judiciary should reject it outright, let alone even consider it.

“If it is used, it should solely be for preliminary investigation and to maintain a list of suspects. The polygraph is unsuited in actually determining if an individual is an actual perpetrator in a case,” he said.

Adding that human behaviour cannot be determined by any kind of technology or machinery, Sundramoorthy said he disapproves whenever investigating authorities publicly state they are using polygraphs in the course of an investigation.

“It makes no sense and is unprofessional since they should be tight-lipped about their investigation proceedings.

“One could also say it is frightening, since the public may get a misleading impression that polygraphs are heavily relied upon. Stressing its use is, in my view, the wrong approach of indicating how criminal justice operates in Malaysia,” he said.

Sundramoorthy's fellow colleague Geshina Ayu Mat Saat also concurred, saying the use of polygraph tests remains controversial ever since modern lie detection machines and tests began at the start of the 20th century.

“Some researchers and practitioners advocate for its usage and value in crime investigations, whilst others discourage its usage based on issues of scientific reliability,” she said.

Although lie detection methods were refined from 1914 to 1924, Geshina said many courts around the world considered polygraph results to be inadmissible, citing the United States as an example.

“Prior to July 1981, stipulation between the prosecution and the defense was a vehicle for the admittance of polygraph, with the Wisconsin Supreme Court subsequently ruling to disallow the stipulation.

“At present in the US, only a statement (confession) is admissible at the trial level, though Law enforcement agencies today utilise polygraph as an investigative tool,” she said.

The criminologist cum psychiatrist added that more recent research since the early 1990s has shown that the reliability of question sets (control and concealed information) in polygraph tests range between 78 per cent to 90 per cent for detecting deception and the accuracy rate for determining whether an individual has knowledge of certain aspects of an event.

“However, it is notable that there are outlying studies who have found extremely different levels of accuracy,” Geshina said.

On their part, legal experts are more ambivalent about the idea of using polygraph test results as evidence in court. Advance Tertiary College academic director and senior lecturer Daniel Abishegam said there is no current case law, to his knowledge, where polygraph evidence has been accepted in court.

“I do not see any bar in the Evidence Act 1950 to stop the admission of a polygraph. Because it is essentially the evidence of the polygraph test's administrator in stating his findings, based on the results.

“The judge may allow the evidence, and then give that evidence as much weight as it deserves. The administrator will be open to cross-examination as well to ensure fairness while the flaws of the polygraph test will be considered by the judge,” he said.

Despite its shortcomings, Abishegam said polygraphs should be allowed if it can form one piece of evidence that, together with other evidence, can point towards the truth.

“However if it is the only evidence available, then I do not think it is enough. Polygraph tests can be an indicator of whether a person is lying but I think it cannot be conclusive.

“It is a measure of the body's reaction to the question and stress levels. People react to different levels of stress differently. I also think a person can train to control these reactions,” he said, adding that it is up to the test administrator to ultimately determine if a suspect's response is a lie or not.

Abishegam said that although polygraphs are certainly not as conclusive as fingerprints or DNA evidence, it is ultimately the judge's decision on the value of the evidence looking at all surrounding circumstances.

Lawyer Rajesh Nagarajan said given the ambiguous nature of polygraph tests, it will be up to the judiciary to establish a test or requirement before such evidence can be admitted in court.

“The onus is on our legislature to enact laws to govern this area. However since Parliament is generally slow it is possible for our judiciary in the interim to adopt the test for the admission of polygraphic evidence from other Commonwealth jurisdictions, such as India or the UK,” he said.

Earlier in October, Chief Justice Tan Sri Tengku Maimun Tuan Mat said a proposal was being studied by the judiciary to allow the use of polygraph test results as evidence in court. She said the proposal involves amendments to the Evidence Act, before it can be permitted as admissible.

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