Sally Clark died on Thursday night of a broken heart. It was broken by the failings of the criminal justice system. Precisely what caused her heart to stop that night is something her family has not spoken about, but they hardly need to.

She died because she could not recover from the terrible wrongs that had been done to her. She is the woman who was jailed in 1999 — wrongly, inexcusably and largely on the expert evidence of Sir Roy Meadow — for killing her two baby sons. While awaiting trial she gave birth to a third son. She lost him, too; he was taken away from her, before she had been found guilty, and given to foster parents.

After losing an appeal and spending more than three years in prison, she appealed again because her husband had unearthed important evidence and her conviction was overturned in 2003. She went home and her long-lost son was returned to her but her ordeal was not over. A self-appointed expert, Professor David Southall, then publicly accused Sally Clark’s husband Stephen of murdering the two boys. Finally Southall was found guilty of serious professional misconduct, and the Clarks were at last left to try to recover. Mrs Clark never did.

It is a heartbreaking story. Imagine the misery and the despair, as a mother, of suddenly losing your newborn babies, one after the other, only to be accused of killing them, of suddenly being surrounded with suspicion and contempt. Imagine the agony of having your only surviving baby, only 10 days old, torn from your breast and given away to strangers in case you murdered him, too. Imagine the horrors of prison and the vicious abuse of fellow prisoners, who always persecute child killers. Sally Clark was so damaged by her time in jail that she was unable to speak about it. It would have been bad for a woman who was unbalanced enough to have killed her babies. For a woman who was innocent it must have been intolerable. Sally Clark could not bear it.

Her trial turned on whether two such deaths could possibly be a coincidence. Two points were crucial. One was the evidence of the expert witness, Professor Meadow, a man who has since become notorious for his part in this and other similar cases. He opined that the probability of two natural and unexplained cot deaths in a family was 73m to 1. He also, such was his sensitivity to the situation, compared the odds to that of a punter successfully backing a horse at 80-1 in the Grand National four years running. How terrible it must have been for Sally Clark to listen to this bluff stuff in court. Much later the Royal Statistical Society and other experts argued that the odds were in fact closer to 200-1; a less self-assured man than Sir Roy would not have blundered into statistics he neither knew nor understood.

The other point was the inexplicable failure of another expert witness, Alan Williams, the Home Office pathologist, to disclose centrally important medical evidence; his tests showed that one of the babies had lethal levels of bacterial infection in his blood, indicating that he died of natural causes but — incredibly — neither Mrs Clark’s defence team nor the jury were shown these results. It is only because her very persistent husband managed to unearth this crucial evidence later on, that his wife’s second appeal was successful and firmly rejected Meadow’s evidence.

Two years later Sir Roy was found guilty of serious professional misconduct and straying outside his remit of expertise by the General Medical Council and struck off the medical register. Both these judgments were later overturned on appeal — another blow for the Clarks, I imagine.

All this is bad enough. Quite apart from killing Sally Clark, the criminal justice system in this case has been brought into disrepute by incompetence, arrogance, inattention to detail, more than a whiff of cronyism, and above all a glaring lack of common sense. What makes it still worse is that it is not an isolated case. There are several other horrifying examples of parents wrongly accused of harming their children.

A recent one is the story of Christian Blewitt whose adoptive parents were accused of torturing and killing him by force-feeding him teaspoons of salt — something that common sense will tell you is almost impossible to do, because it instantly induces vomiting. Common sense would also wonder why two intelligent, sensible and normal people, who had recently been through all the scrutiny of adoption vetting, might want to hurt their little boy and in such a bizarre way; it is after all most unlikely. After a terrible four years of torment, in and out of courts and jails, the parents were finally acquitted in a second trial, after the jury accepted evidence that Christian had abnormal blood salt levels which could have killed him.

It seems that the system is incapable of learning from experience. Nearly 20 years ago, there was a very ugly case in Cleveland, in which many parents were separated from their children on suspicion of sexually abusing them; the evidence came from one obsessional woman doctor. The parents were found innocent in the end, but some of them didn’t see their children for years. In the inquiry that followed, the then Justice Elizabeth Butler-Sloss warned against excessive reliance on expert opinion without corroborative evidence. The same warning still needs to be made and heard.

In particular, too much deference is paid to expert medical witnesses. In a court of law one should be sceptical about everything and everybody, not least experts who may, as a result of their eminence, lack the modesty scientists ought to feel in the face of scientific complexity and uncertainty.

The best doctors are constantly aware of their own ignorance, and the way that theories and fashions in medicine are constantly changing. Because lesser doctors are not, however eminent and expert they might appear, every expert medical view in court should be corroborated by an independent expert, or thrown out (right or wrong). That, in turn, should be corroborated by other evidence, or ignored.

In the case of child abuse, moral panic seems to set in and people are tempted to believe the worst without proper evidence. The results are all too often tragic.

minette.marrin@sunday-times.co.uk

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