Lucy Letby: the judge’s direction

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In his summing up to the jury, Mr Justice Goss instructed the jury:

“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 the subject of the count on the indictment and the act or acts were accompanied by the intent and, in the case of murder, was causative of death [...].”

As a principle of law, this is undoubtedly correct. It serves to resolve a probabilistic paradox which might otherwise arise where there is no doubt that the defendant murdered the victim, but it is just not clear precisely how. The burden of proof is discharged without knowing the exact method of murder. But this scenario — where all innocent causes of death can be ruled out — is unusual.

We focus on the first part of the test but it is the second that bites. How can you be sure that the defendant is a murderer if you don’t know how she did it? Only if there is evidence so directly implicating the defendant as to rule out anyone else.

It is hard to frame hypotheticals here because usually the sort of evidence that makes you certain a defendant is guilty is direct eye witness evidence of them committing the crime. If there is unequivocal evidence that the defendant was murdered — stab wounds, gun shots and so on — it is usually not difficult to infer a detailed means of death.

There are unusual cases where it might have been a kick or a punch, but it definitely was the defendant — but these are rare, and the authorities really stand only to head off cute arguments from enterprising defence lawyers who are otherwise out of ideas..

This case is different. Here there is real doubt as to how the victims died. Distinction between similar methods, there is no information about core of death at all guarantee the cause of death was murder at all..

A direction to the jury that you don't need to be sure how the defendant did it as long as you are sure that they did it is dangerous. It may be construed as permission to lower the analytical standard. How are you supposed to be sure that the defendant did it if you don't know how they did it? This is particularly acute where speculative evidence has been introduced but badged as expert scientific evidence

Here

Secondly, direct evidence might positively implicate the defendant. Here the defendant’s skull is intact, but tests return an unusually high insulin reading. This might be consistent with undiagnosed hypoglycaemia, but if the defendant was reliably witnessed administering insulin ten minutes before the victim collapsed, we can rule out hypoglycaemia as an operating cause of the collapse.

In the first of these cases we might be sure that it is murder even if we don’t know the precise method; in the second case we can only be sure it is murder because we know the precise method. This is the evidence that excludes non-malicious alternative explanations.

In Ms Letby’s case, the equivalent scenario would be that all reasonably plausible means of death involved Ms. Letby’s malice. Given the evidence, no explanation not involving the defendant’s malice is reasonably plausible.

But here the victims’ “manner of collapse” does not imply malice. In every collapse that led to a formal medical examination, the original conclusion — based on the best evidence — was natural causes.

And nor did any independent evidence positively suggest Ms. Letby’s intervention in the collapse. There is no evidence that Ms Letby obtained any insulin, let alone administered it, nor that she injected air, overfed or assaulted any of the victims.

We are not in a situation where “all plausible causes of death involved Ms Letby. There are plausible innocent explanations.

So the second part of the judge’s direction, not the first, is the important part.

You must be sure that she deliberately did some harmful act.

It is hard to see how a jury could be sure Ms Letby did some harmful act without compelling evidence as to what that act was.

Unless, of course, the persuasive implicating evidence was the implausible coincidence. Once my be happenstance, twice coincidence, but by the time we get to the fifteenth occasion we are surely past the point of even enemy action. But this is not positive, active evidence, but deduction. Its credibility can only be assessed by a probabilistic analysis, and one was not carried out.

Now these findings are not determinative of Ms. Letby’s innocence, but they do indicate there are plausible alternative explanations such that the jury cannot be sure, without better evidence, that Ms Letby was responsible.

The judge later directed the jury:

“In the case of each child, without necessarily having to determine the precise cause or causes of their death, and for which no natural or known cause was said to be apparent at the time, you must be sure that the act of acts of the defendant, whatever they were, caused the child’s death, in that it was more than a minimal cause. The defendant says that she did nothing inappropriate, let alone harmful to any child. Her case is that the sudden collapses and deaths were or may have been from natural causes or from some unascertained reason or from some failure to provide appropriate care and were not attributable to any deliberate harmful act by her.”