Witness testimony needs scientific backing, SC rules

Judgment in murder appeal may set precedent for future handling of eyewitness testimony

ISLAMABAD: The top court has emphasised the need to accommodate more scientific proof in the realm of Pakistan's legal system to assess the reliability and credibility of the evidence.

"If scientific research can help and assist the court in understanding and appreciating evidence more fully and more meaningfully, the risk of a miscarriage of justice stands minimised. Therefore, the courts shouldn't shy away from scientific developments, but instead should reach out and embrace them. Reliance on scientific research and the factors evolved by science to assess the reliability and credibility of the eyewitness can improve the quality of identification evidence, and as a consequence, the quality of justice", says a 14-page judgment authored by Justice Syed Mansoor Ali Shah which acquitted two men previously convicted of killing a man during a robbery. They were acquitted on the basis of 'estimator variables' – scientifically unreliable witness testimony.

Chief Justice of Pakistan Asif Saeed Khosa and Justice Sajjad Ali Shah were also members of the bench.

The judge writes that our jurisprudence had already been moving in this direction, and now, credible scientific research, by providing us additional factors or "estimator variables" has provided additional factors to certify the credibility and reliability of eyewitness testimony and identifications.

Justice Shah further says that when an identification parade is part of the evidence, the court must verify the credibility of an eyewitness by assessing the evidence on the basis of estimator variables.

The judgment explains that the process of memory retention and retrieval may be affected by a number of factors. Scientific literature divides those variables into two broader categories – system and estimator variables.

System variables are factors like lineup procedures which are within the control of the criminal justice system, such as the test identification parade. Estimator variables are factors related to the witness, such as distance, lighting, or stress – things over which the legal system has no control.

"Our courts have marginally attended to this aspect of witness reliability before placing reliance on the identification evidence.  The laws of evidence maintain that in order for the court to take judicial notice of scientific facts they must be part of the general knowledge of men or must be agreed upon by reputable men in a particular field of science beyond reasonable dispute," says the judgment.

Estimator variables

The court notes that scientific research establishes that "estimator variables" negatively affect the memory process.

These variables include stress, weapon focus, duration, distance and lighting, witness characteristics, memory decay, and the characteristics of the perpetrator.

On stress, the court said that even under the best viewing conditions, high levels of stress can diminish an eyewitness' ability to recall and make an accurate identification. It may be noted "while moderate levels of stress improve cognitive processing and might improve accuracy, an eyewitness under high stress is less likely to make a reliable identification.

Of weapon focus, the judgment noted that when a visible weapon is used during a crime, it can distract a witness and draw his or her attention away from the culprit. Weapon focus can thus impair a witness from making a reliable identification and describing what the culprit looks like if the crime was committed in a very short duration.

On a similar note, the amount of time an eyewitness has to observe an event may affect the reliability of an identification. There is no minimum time required to make an accurate identification, the judge notes, "but a brief or fleeting contact is less likely to produce an accurate identification than a more prolonged exposure."

Distance and Lighting factor in because a person is easier to recognise when close by, and that clarity decreases with distance. Also, as poor lighting makes it harder to see well, "greater distance between a witness and a perpetrator and poor lighting conditions can diminish the reliability of an identification."

Witness Characteristics such as age and level of intoxication can affect the reliability of an identification. An example was provided of children between the ages of nine and thirteen who view target-absent lineups. They are more likely to make incorrect identifications than adults.

The characteristics of the perpetrator, such as disguises and facial hair, can be altered between the time of the event and the identification procedure, which can affect the accuracy of an identification.

Meanwhile, memories can fade with time and memory decay "is irreversible", as memories never improve. As a result, delays between the commission of a crime and the time identification is made can affect reliability.

The court also notes that the laws of evidence maintain that in order for the court to take judicial notice of scientific facts, they must be part of the general knowledge of men or must be agreed upon by reputable men in a particular field of science beyond reasonable dispute. On this, the court notes that for judges to determine the degree of consensus on a particular scientific fact, they may refer to any reputable and recognised reference sources, adding that the court can take judicial notice of credible scientific developments under Article 112 of Qanun-e-Shahadat, 1984.

International scientific surveys

The judgment says that International scientific surveys revealed that eyewitness testimony has been the most popular topic in psycho-legal research. By 1995 alone, there were over 2,000 publications in psychology concerned with eyewitness reliability.

"The single most important observation from the research on eyewitness identification is that it is substantially less accurate than generally believed. Overall, data from real-life cases show that under 45 per cent of witnesses pick the suspect, about 35 per cent decline to make a choice, and about 20 per cent pick innocent fillers [in police line ups]. The overreliance on visual identification evidence has led to numerous mistaken identifications of innocent suspects and consequently wrongful convictions, the judgment notes. "In approximately 75 per cent of DNA exonerations in the United States, mistaken identification was the principal cause of wrongful conviction. Furthermore, in 80 to 90 per cent of all DNA exonerations, at least one eyewitness made a mistaken identification. A wrongful conviction results in two injustices. The first tragedy is to the innocent person. The second is to the victim of the offence and to society; because the real offender is not brought to justice."

The judgment says that wrongful convictions undermine the credibility of the legal system. Whenever witnesses are mistaken, it is rarely because they lie or misrepresent facts, but mostly because they misidentify people.

The scientific research refutes the notion that memory is like a video recording, and that a witness needs only to replay the tape to remember what happened. Human memory is far more complex. The memory is a constructive, dynamic, and selective process. The process of remembering consists of three stages: acquisition, or the perception of the original event, retention, meaning the period of time that passes between the event and the eventual recollection of a particular piece of information, and retrieval, which is a stage during which a person recalls stored information.