Lucy Letby was never seen to harm any babies, and almost all the babies who died had autopsies that identified natural causes or raised the possibility of accidents. The medical evidence against her started to be constructed only after her supposed killing spree had ended, by which time evidence was limited to what could be found in the medical notes or could be recalled by the four doctors who took their suspicions to the police.
The murder methods attributed to Letby were many, but the explanations followed three patterns.
The first pattern started by identifying a commonplace symptom and then arguing that this symptom was explained by deliberate harm. This explanation pattern was initially developed to allege that Letby was attacking babies by injecting air into the vein to cause an air embolism. This then became the template for explanations using other commonplace symptoms, such as bleeding, as their starting point.
The second pattern was much more specific. Test results, it was said, showed the presence of artificial insulin. Here, it was argued, there was direct evidence of poisoning.
The third pattern took a baby’s sudden, unexpected and (supposedly) unexplained collapse as evidence enough of foul play: the very fact that a baby had collapsed, even in the absence of evidence of commonplace symptoms, including air, was sufficient to diagnose that air had been deliberately administered to the baby. This diagnosis used a process of elimination. As Dr. Dewi Evans, the main expert witness for the prosecution, put the matter when looking back on the trial:
These are cases where your diagnosis is made by ruling out other factors, and you end up with the diagnosis where this is the only explanation. You’ve ruled everything out; what’s left is the diagnosis.
This medical evidence has now been so thoroughly discredited that it appears, almost literally in some cases, to have been conjured up out of the air. On May 13th 2024, a long article by Rachel Aviv in the New Yorker set out many of the problems in all of the evidence against Letby, including the medical evidence. (The article was censored in the U.K. due to ongoing trial but was easy enough to find online.) Then, on July 9th, two substantial articles in the Guardian and the Telegraph focused on flaws in the medical evidence. Both articles cited numerous medical experts, including neonatologists, who explained that there are any number of natural and accidental explanations that might account for the symptoms said to be evidence of murder or attempted murder. None of the supposed murder methods were viewed as more than possibilities, and unlikely ones at that.
The idea that babies were being murdered by forcing air into the stomach came in for particular criticism. The insulin evidence, superficially more convincing, was immediately invalidated by the testing facility explicitly warning that the test could not be used as evidence of poisoning. But even leaving this aside, several experts explained how the test results had been misinterpreted. As for Dr. Evans’s methods of diagnosis, no one amongst the experts had a kind word to say about them, and some were more or less openly contemptuous. More generally, the articles highlighted shortcomings in the state of the neonatal unit at the Countess of Chester Hospital where Letby worked, ones which suggested that insofar as the collapses and deaths of the babies were not the inevitable result of natural causes, they were the result of substandard care.
Given that the medical evidence against Letby is so poor, why was it that, on May 24th 2024, Dame Victoria Sharpe, Lord Justice Holroyde and Mrs Justice Lambert announced they would not allow Letby to appeal against her convictions?
To find the answer we need to look at the reasoning that underlies their judgment, published on July 2nd 2024. However, before entering in to this reasoning, I first rule out three explanations for why the judges denied the appeal.
- Were the judges so constrained by the laws on appeal that they could not do otherwise? No. I rule this out with the general observation that judges have considerable flexibility. The Appeal Court judges could have easily come up with reasons to grant leave to appeal if they had wanted to.
- Did the judges realise that Letby should never have been found guilty, but decide to deny her leave to appeal anyway for reasons of their own? No. I rule this out on the grounds that the judges were mistaken rather than evil.
- Did the judges arrive at their decision by knowingly drawing on the reasoning in comparable cases in the past? No. I rule this out because there are no references in the judgment to such cases. There have occasionally been cases that seem closely comparable to Lucy Letby’s, including the Lucia de Berk case in Holland, when a paediatric nurse was convicted of multiple murders and attempted murders, and was only some years later found not to be guilty after all. Obviously the judges did not consider this case. However, there are also a large number of U.K. cases, including civil cases, that are broadly similar to the Letby case insofar as: (a) babies or children have died or have signs of injuries; (b) the evidence that the death or injury has been caused by the suspect (typically a parent or step parent) is circumstantial; (c) the question of whether natural or accidental explanations for the deaths or injuries are plausible is critical to the outcome of the case; and (d) there is contested expert medical evidence.
There is surely much wisdom contained in the judgments of these other cases. And had they considered them this might have helped the Appeal Court judges in their reasoning over what is needed, in these types of circumstances, to get at least some way towards certainty of guilt (civil cases are decided on the balance of probabilities). Whether the accumulated wisdom to be found in these cases would have supported the judges in upholding Letby’s guilty verdicts is another matter. But all this is bye the bye, as the Appeal Court ignored the whole lot.
So what explains the reasoning of the judges? In part they simply took a view diametrically opposed to those of the medical experts cited in the New Yorker, Guardian and Telegraph articles. Thus, they argued that Dr. Evans had been maligned by the defence and, they implied, by a judge who had called his opinion in another case “worthless”. Dr Evans, they argued, had a sound holistic method of diagnosis. Furthermore, it was Evans, they said, who had discovered the insulin evidence (although Dr. Stephen Brearey emphatically claimed that he had); this insulin evidence provided proof of poisoning, and so on. However, the judges’ reasoning also explicitly followed a legal pattern of argument that had been developed particularly when dealing with fraud cases.
Fraud cases are notoriously complicated for jurors to understand, so to make things as easy as possible for them, judges draw the distinction between (a) what is essential to secure a conviction and (b) what is a mere matter of ancillary detail. “Concentrate on the essentials,” the judge tells the jury. “If you are sure that the defendant is guilty on the grounds of these essentials, you do not need to agree over the matters of detail.” The Appeal Court took this distinction and applied it to the medical evidence in the Letby case. The medical evidence contributed to the evidence as a whole, but it was only as part of this whole that it could be said to be essential. Considered in isolation, the medical evidence was a matter of detail; it was not essential to the prosecution case.
This argument comes out when the Appeal Judges explain that Judge Goss was quite right to tell the jury that it could convict Letby of murder and attempted murder even if it was unsure of precisely how she killed or tried to kill the babies. Goss had said:
If you are sure that someone on the unit was deliberately harming a baby or babies you do not have to be sure of the precise harmful act or acts; in some instances there may have been more than one. To find the defendant guilty, however, you must be sure that she deliberately did some harmful act to the baby. (para 155)
Letby’s defence argued that this was a misdirection: that without knowing how Letby killed or tried to kill the babies, one could not be sure that she had done so at all, given the possibility that deaths and injuries might have natural and accidental causes (including substandard care).
The prosecution countered that “they did not have to prove the precise – or any – mechanism by which death was caused or attempted” (para 159). After reminding the Appeal Court judges of famous cases in which murder convictions had been obtained without a body, the prosecution then brought up the distinction so useful to fraud cases, between matters which are essential, “an ingredient of the offence”, and those that are “a merely evidential – or ancillary – issue”.
The appeal judges agree with this distinction (para 160). They explain it using a hypothetical example that if a jury were sure that someone caused actual bodily harm by having “unlawfully punched and/or kicked his victim”, it was a mere matter of detail as to whether it was a punch or a kick or both that caused the injury; there is no need to be precise about it. But then (para 163) they seem to have second thoughts, raising a well-known complication in a real case involving a fatal attack. In this case, the defence’s argument is different according to “whether the fatal blow was a kick (to which the defendant’s defence was identification) or a punch (to which his defence was self-defence)”. Here a punch or a kick is not a mere matter of detail because the jurors might find one defence plausible and the other not. In such a case, therefore, the jury have to decide on the precise blow before they can be sure whether to convict.
The Appeal Court was quite right to raise this complication, as the medical evidence is clearly of this type. The various alleged ways in which Letby killed or harmed babies each had different alternative natural and accidental explanations put forward by the defence. For example, the defence argued that liver damage in the case of Baby O might have been caused inadvertently by CPR, or by insertion of a cannula, whereas air in the stomach may have been an inadvertent side effect of CPAP, and so on. The jurors might find at least some of these accidental or natural explanations plausible. Therefore, in order to be sure to convict, the cause (or causes) of death or of harm for each baby had to align precisely with ones where the jurors agreed that the specific alternatives put forward by the defence could be ruled out.
It is at this point that the Appeal Court judges make a bizarre mistake in their reasoning. They argue the opposite, that the medical evidence in the Letby case was akin to the hypothetical situation where whether it was a punch or a kick did not matter. The jury, they claimed, could exclude all the possibilities put forward by the defence without needing to agree “on the precise act or acts which the applicant committed” (para 165). The judges asserted that the jury could exclude these possibilities by considering not just the medical evidence but the evidence as a whole, including things such as the apparent confession on the post-it note and the “trophies” (meaning the handover notes) (para 164).
How such non-medical evidence rules out the possibility that, say, bruising on the liver is the result of CPR, the judges do not explain. But perhaps this lacunae helps to explain their own thinking. The judges sound rather tired of trying to get their heads around the case. They write virtuously of having to read “a vast volume of material” (para 17). No wonder it was tempting, even if mistaken, to categorise the medical evidence as an ancillary matter; the tiresome business of going through all the medical evidence bit by bit could thereby be disposed of by the Appeal Court judges, just as it could be by the jury at the trial. It was just a matter of detail. It was the whole thing that made Lucy Letby guilty.
In a case involving so many alleged victims, this reasoning would be highly suspect even if the non-medical evidence was strong. In fact, the other evidence was remarkably weak: the handover notes, the Facebook searches, the roster chart, all were cherry picked. The swipe data, on who was and who was not present at each incident, has had its accuracy called into question by the retrial.
The only substantial evidence against Lucy Letby is the post-it note, in which she wrote “I am evil I did this.” This, the prosecution claimed, provided the case against her “in a nutshell”.
The post-it note provides real evidence, but what this evidence means is ambiguous. When isolated individuals are remorselessly pursued by powerful authorities, they often do confess to things, as ‘witches’ confessed to flying on broomsticks. And if we are to believe the note, which part of it are we to believe? It cannot all be true, because in the very same note, Letby said that she had done nothing wrong, and that the police investigation was founded on slander, discrimination and victimisation. Given all that we now know, it is surely far more likely that it is this part of the note that puts the case against Letby in a nutshell.
Dr. Peter Hayes was for many years a Senior Lecturer in Politics at Sunderland University. With academic research interests cutting across medicine and law, he authored numerous publications in both medical and legal journals.
Stop Press: Several former Cabinet ministers have expressed concern over the conviction, with the issue likely to be raised in Parliament, according to the Telegraph. The Royal Statistical Society has also announced it will “convene a meeting”, stating that it is aware of “concerns” from RSS members and the wider community regarding the use of statistical evidence in the case.
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