This site frequently mentions cases where parents or others kill children and escape with ridiculously lenient sentences. But there is another sort of injustice, and that is where overzealous officials use pseudoscientific nonsense to create a hysteria that convicts people of crimes that they did not commit.
Such a wave of hysteria hit the United Kingdom in the late 1990s when a number of women were convicted of multiple homicides in deaths that the defense claimed were due to Sudden Infant Death Syndrome.
Rather than just relying on the physical evidence of autopsies, etc., prosecutors also pulled in alleged experts like Dr. Roy Meadow who testified that the odds of a couple having more than one child die from SIDS was astronomically low.
For example, Sally Clark was convicted of murdering her 11-week old son Christopher in 1996 and her eight-week old son Harry in 1998. Clark’s defense was that the children died from SIDS. But Meadow testified at her trial that the odds of the two boys dying from SIDS was “one in 73 million.” Meadow provided similar testimony at the murder trials of other women who had more than one child death.
But Meadow’s claim was pure speculation backed up by no evidence. As the Royal Statistical Society noted in a press release it issued about Meadow’s claim,
In the recent highly-publicised case of R v. Sally Clark, a medical expert witness drew on published studies to obtain a figure for the frequency of sudden infant death syndrome (SIDS, or “cot death”) in families having some of the characteristics of the defendant’s family. He went on to square this figure to obtain a value of 1 in 73 million for the frequency of two cases of SIDS in such a family.
“This approach is, in general, statistically invalid. It would only be valid if SIDS cases arose independently within families, an assumption that would need to be justified empirically. Not only was no such empirical justification provided in the case, but there are very strong a priori reasons for supposing that the assumption will be false. There may well be unknown genetic or environmental factors that predispose families to SIDS, so that a second case within the family becomes much more likely.
The well-publicised figure of 1 in 73 million thus has no statistical basis. Its use cannot reasonably be justified as a “ballpark” figure because the error involved is likely to be very large, and in one particular direction. The true frequency of families with two cases of SIDS may be very much less incriminating than the figure presented to the jury at trial.
“Aside from its invalidity, figures such as the 1 in 73 million are very easily misinterpreted. Some press reports at the time stated that this was the chance that the deaths of Sally Clark’s two children were accidental. This (mis-)interpretation is a serious error of logic known as the Prosecutor’s Fallacy. The jury needs to weigh up two competing explanations for the babies’ deaths: SIDS or murder. Two deaths by SIDS or two murders are each quite unlikely, but one has apparently happened in this case. What matters is the relative likelihood of the deaths under each explanation, not just how unlikely they are under one explanation (in this case SIDS, according to the evidence as presented).
It turned out that the odds were actually closer to 1 in 100.
In fact, in December the results of the largest study of second-infant deaths was published and found that a) second-infant deaths are not that rare, and b) in 80 percent of cases, second-infant deaths were due to natural causes rather than homicide.
Published in the Lancet, research by Professor Robert Carpenter, studied all 6,373 families who had lost an infant due to SIDS and the enrolled in a program designed to support them with their next child.
Of those 6,373 families, Carpenter’s research found that 57 of the second-infants died. It found that nine deaths were inevitable, including infants born with severe birth defects, and 48 were unexpected deaths.
After interviewing the families and checking autopsy records, 40 of the unexpected deaths were due to natural causes, while 6 were due to probably homicides.
Carpenter was quoted by the Scotsman as saying,
Our data suggest that second deaths are not rare and that the majority — 80-90 percent — are natural. Families who have experienced three unexpected deaths also occur.
. . .
Consequently, although child abuse is not uncommon, from the best available data we believe that the occurrence of a second or third sudden unexpected death in infancy within a family, although relatively rare, is in most cases from natural causes.
Some of the women convicted based, in part, on the testimony of Meadows have had their convictions overturned, but prosecutors bizarrely say they still have faith in Meadows’ testimony. Sound science is clearly not on their agenda.
Sources:
Royal Statistical Society concerned by issues raised in Sally Clark case. Press Release, Royal Statistical Society, October 23, 2001.
Baby-death study finds natural causes evidence. Lyndsay Moss, The Scotsman, December 31 ,2004.
Profile: Sir Roy Meadow. The BBC, April 11, 2005.
Doubt cast on baby killer case. The BBC, July 15, 2001.
