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Forensic techniques can be unreliable


Forensic techniques can be unreliable

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IN QUESTION TIME in yesterday’s SATURDAY SUN, Law ‘N Order concludes his questions with: “Are all officers subjected to polygraph testing?”

Evidently, Law ‘N Order is unaware that polygraph exams have a 20 per cent error rate. This means that 20 per cent of miscreants are deemed truthful while, more ominously, 20 per cent of the innocent are deemed untruthful, a result that could end an otherwise stellar career.

But that is not all. A September 2016 study in America from the President’s Council of Advisers on Science and Technology concluded that most forensic-evidence techniques – including fingerprint, bite-mark, firearm, footwear and hair analysis techniques – have surprisingly high error rates, and often are “rank guesswork”. Only the most basic form of DNA analysis is scientifically sound, the study found.

This was stunning news, given that courts heavily depend on the kind of forensic evidence glamorised by TV shows like CSI and Forensic Files.

In reality, forensic experts often work for the prosecution, and see their job as helping to secure a conviction. They usually tell juries that their risk of error is vanishingly small or essentially zero, but that’s simply not true.

Bite-mark analysis (there was a case in Barbados several years ago which relied heavily on such analysis) turns out to be totally unreliable.

Fingerprint analysis can be wrong nearly five per cent of the time. When several people’s genetic material is found, even DNA analysis can be subjective and mistaken.

The disturbing truth is that justice systems have sent countless numbers of people to jail – and executed some of them – based on what evidently is junk science.