Science, Statistics, Expert Testimony Important in Finding Justice – Or Innocent People Go to Jail 

Via Pxfuel

By the Vanguard Staff

NEW YORK, NY – “The city of New York recently witnessed a record payout to George Bell, falsely convicted of murder in 1999, after it emerged prosecutors had deliberately hidden evidence casting doubt on his guilt, giving false statements in court,” according to a story in Scientific American.

Bell, said Scientific American, is the latest in a long line of people, especially Black Americans, unfoundedly convicted, noting that recently Jabar Walker and Wayne Gardine were cleared after decades in prison. 

Conviction integrity units in North America have uncovered serious flaws with many convictions.

“Alarmingly for scientists, misleading forensic and expert evidence is too often a deciding factor in such miscarriages of justice; of the 233 exonerations in 2022 alone recorded by the National Registry of Exonerations, deceptive forensic evidence and expert testimony was a factor in 44 of them,” wrote Scientific American.

“In an era of high-tech forensics, the persistence of such brazen miscarriages of justice is more than unsettling. The National Institute of Justice, part of the U.S. Department of Justice, has just published a report that found certain techniques, including footprint analysis and fire debris, in forensic science were disproportionately associated with wrongful conviction.

“The same report found expert testimony that ‘reported forensic science results in an erroneous manner’ or ‘mischaracterized statistical weight or probability’ was often the driving force in false convictions. The disconcerting reality is that illusions of scientific legitimacy and flawed expert testimony are often the catalyst for deeply unsound convictions,” said Scientific American.

“This paradox arises because scientific evidence is highly valued by juries, which often lack the expertise to correctly interpret or question it. Juries with a lower understanding of the potential limitations of such evidence are more likely to convict without questioning the evidence or its context,” said the Scientific American story. 

The piece added, “This is exacerbated by undue trust in expert witnesses, who may overstate evidence or underplay uncertainty. As a 2016 presidential advisors report warned, ‘expert witnesses have often overstated the probative value of their evidence, going far beyond what the relevant science can justify.’

“The debacle of British pediatrician Roy Meadow serves as a powerful exemplar of precisely this. Famed for his influential ‘Meadow’s law,’ which asserted that one sudden infant death is a tragedy, two is suspicious, and three is murder until proved otherwise, Meadow was a frequent expert witness in trials in the United Kingdom. His penchant for seeing sinister patterns, however, stemmed not from real insight, but from terrible statistical ineptitude.”

In the late 1990s, the Scientific American story reported, “Sally Clark suffered a double tragedy, losing two infant sons to sudden infant death syndrome. Despite scant evidence of anything beyond misfortune, Clark was tried for murder, with Meadow testifying to her guilt. In court, Meadow testified families like the Clarks had a one-in-8,543 chance of a sudden infant death syndrome (SIDS) case. Thus, he asserted, the probability of two cases in one family was this squared, roughly one-in-73 million of two deaths arising by chance alone. 

“In a rhetorical flourish, he likened it to successfully backing an 80-to-1 outsider to win the Grand National horse race over four successive years. This seemingly unimpeachable, damning statistic figure convinced both jury and public of her guilt. Clark was demonized in the press and imprisoned for murder.”

“Yet this verdict horrified statisticians, for several reasons. To arrive at his figure, Meadow simply multiplied probabilities together. This is perfectly correct for truly independent events like roulette wheels or coin-flips, but fails horribly when this assumption is not met,” wrote the magazine.

Then, in the 1990s, overwhelming epidemiological evidence found SIDS ran in families, rendering assumptions of independence untenable, said Scientific American, adding, “More subtle but as damaging was a trick of perception. To many, this appeared equivalent to a one-in-73-million chance Clark was innocent. While this implication was intended by the prosecution, such an inference was a statistical error so ubiquitous in courtrooms it has a fitting moniker: the prosecutor’s fallacy.

“This variant of the base-rate fallacy arises because while multiple cases of SIDS are rare, so too are multiple maternal infanticides. To determine which situation is more likely, the relative likelihood of these two competing explanations must be compared. 

“In Clark’s case, this analysis would have shown that the probability of two SIDS deaths vastly exceeded the infant murder hypothesis. The Royal Statistical Society issued a damning indictment of Meadow’s testimony, echoed by a paper in the British Medical Journal. But such rebukes did not save Clark from years in jail,” Scientific American noted.

Clark’s verdict was overturned in 2003, and several other women convicted by Meadow’s testimony were exonerated. The General Medical Council found Meadow guilty of professional misconduct  and barred him from practicing medicine.   

Scientific American noted the “prosecutor’s fallacy emerges constantly in problems of conditional probability, leading us, siren-like, towards precisely the wrong conclusions—and undetected, sends innocent people to jail.”

About The Author

The Vanguard Court Watch operates in Yolo, Sacramento and Sacramento Counties with a mission to monitor and report on court cases. Anyone interested in interning at the Courthouse or volunteering to monitor cases should contact the Vanguard at info(at)davisvanguard(dot)org - please email info(at)davisvanguard(dot)org if you find inaccuracies in this report.

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