FINGERPRINTS were once the cornerstone of forensic identification. Now a report into a miscarriage of justice has renewed pressure on print examiners to improve their methods, while two new studies reveal the extent of their fallibility. The results could change the fingerprint profession worldwide.Yes, fingerprint evidence is fallible. It is not 100% certain. Just like all other expert evidence.
The Fingerprint Inquiry was launched by the Scottish government after detective Shirley McKie was acquitted of perjury. Flawed fingerprint analysis was the only evidence against her. The report, published on 14 December, concludes that human error was to blame and voices serious concerns about how fingerprint analysts report matches. It recommends that they no longer report conclusions with 100 per cent certainty, and develop a process for analysing complex, partial or smudged prints involving at least three independent examiners who fully document their findings.
The recommendations lay bare fundamental problems which have demanded attention for decades, says Jim Fraser, a forensic scientist at the University of Strathclyde in Glasgow, UK.
FBI fingerprint experts have always testified that their matches are 100% certain. They are not. They are lying every time.
A basic requirement of any expert witness is to describe how often he is wrong. If he does not know how likely his opinion is to be wrong, then his opinion is worthless.
Family court psychologists and other expert witnesses are orders of magnitude worse than the fingerprint experts. The psychologists are never able to say anything about the reliability of their opinions about child custody and visitation. That alone is reason to reject their testimony.