New: the Lucy Letby trial ruling on the submission of 'no case to answer'
A court document that sets out why the judge did not throw out key expert evidence
So as to assist in the public understanding of law, the Substack now publishes a significant legal document from the first Lucy Letby trial.
In doing this, and as set out in the post earlier today, no view is taken on the guilt or innocence of Lucy Letby.
The published legal documents on the Letby matter are here.
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By way of background: at the end of the prosecution case in the first trial, the defence applied to have a number of the counts against Letby dismissed on the basis that the prosecution evidence, taken at its highest, was such that a jury properly directed could not properly convict on that evidence.
The ruling of the judge, which I have now obtained from the UK judiciary office, is now set out below.
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Paragraphs [1] and [2] introduce the ruling, and also explain why the applications were not an abuse of process.
The applicable test for the applications is set out in paragraph [3].
The judge’s summary of the defence submissions is then set out in paragraphs [4] to [11]. Here is it is important to note that the judge is describing what the defence are saying, and not what the court has decided.
Paragraph [12] summarises the prosecution case - and again it is important to note that the judge is describing what the prosecution are saying, and not what the court has decided.
The key paragraph is [13] where the judge sets out his reasons why the applications should be refused.
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The redactions refer to Baby A (Count 1), apart from the first redaction in paragraph 6 which is to Baby B (Count 2). These redactions are from the court office and not from me.
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As a guide, this table is from the court of appeal decision on the first trial - please note this table is not part of the ruling published below:
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The judiciary office also says:
“The ruling is a public document.
However, the reporting directions/restrictions apply to the reporting of its contents.
Accordingly, there should be no reference to anything that might lead to the identification of any person the subject of any current reporting directions.
To avoid any potential breach of the reporting directions, the names […] should be removed and the letters of the alphabet attributed to them […] should be substituted. Certainly, their names should not be reported.”
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IN THE CROWN COURT AT MANCHESTER
REX
V
LUCY LETBY
RULING ON SUBMISSION OF ‘NO CASE TO ANSWER’
1. The defendant is on trial accused of the murder or attempted murder of 17 babies on the Neo-Natal Unit (‘NNU’) at the Countess of Chester Hospital in Chester between June 2015 and June 2016. The defence, at the close of the prosecution case, have made two linked applications in respect of 9 counts on the Indictment in which there is expert evidence on air embolus. In Counts 1, 2, 4 and 16, the sole alleged cause of the collapse of the child, two of whom died, is air embolus. In Counts 3, 5, 12, 17 and 20, the collapses of the children, two of whom died, include an allegation of air embolus in addition to other causes. On those counts in which the sole alleged cause of death is air embolus, the defence submit that, applying what is conventionally referred to as the second limb of the ‘test’ identified in R v Galbraith (1981) 73 Cr App R 124, the case on those counts should be stopped on the basis that the prosecution evidence, taken at its highest, is such that a jury properly directed could not properly convict on it. In the cases where there are other alleged causes in addition to air embolus, the defence submit that the evidence of air embolus is incapable of supporting a conviction and the jury should be directed to disregard the evidence of air embolus as a cause of death on those counts. The bases of the applications and the reasons relied on by the defence are set out in detail in their written document headed ‘Submission of No Case to Answer’ dated 27th April 2023, and have been expanded upon in oral submissions. The prosecution resist the applications for the reasons set out in their response dated 28th April 2023, which have also been supplemented by oral submissions. They contend that the applications are an abuse of the process of the court, arguing that the application should have been made to exclude the expert evidence before it was called, alternatively, that the matters complained of go to the weight of that evidence or, in the further alternative and if the evidence is excluded, that there is sufficient evidence from the overall circumstances of the case which establishes a case to answer on Counts 1, 2, 4 and 16. At the conclusion of the hearing of the application on 28th April, I indicated that the applications were refused for reasons that I would put into writing. These are my reasons.
2. I do not find the applications to be an abuse of the process of the court. It is open to any defendant at the conclusion of the prosecution evidence to submit that, at this stage of the proceedings, the evidence is insufficient for a jury properly directed to convict the defendant of the offence(s) upon which they are being tried. I also disregard the contents of the reports of Dr Michael Hall, the expert neonatologist instructed by the defence: those reports are not in evidence. Accordingly, it is appropriate for me to determine the applications on their merits and according to established legal principles.
3. The relevant test under the second limb of R v Galbraith (1981) 73 Cr App R 124, as set out by Lord Lane CJ on p.127 is that
“… (2) The difficulty arises where there is some evidence but it is of a tenuous character, for example, because of inherent weakness or vagueness or because it is inconsistent with other evidence. (a) Where the judge concludes that the prosecution evidence, taken at its highest, is such that a jury properly directed could not properly convict on it, it is his duty, on a submission being made, to stop the case. (b) Where however the prosecution evidence is such that its strength or weakness depends on the view to be taken of a witness’s reliability, or other matters which are generally speaking within the province of the jury and where on one possible view of the facts there is evidence on which the jury could properly come to the conclusion that the defendant is guilty, then the judge should allow the matter to be tried by the jury”.
4. The heart of the defence submission is that the expert medical evidence that is fundamental to the allegations in the cases of each of the children identified in the respective counts that are the subject of the applications and the scientific basis for air embolus is so weak that it fails to provide the level of reliability required to support the allegations. For this reason, they argue, a jury properly directed could not properly convict on it. Their submission is not concerned with the evidence of air embolus as it applies to individual counts; rather it is directed at the underlying consistency, coherence and reliability of the scientific knowledge supporting the theory and diagnosis of air embolus, and whether this provides a sufficiently clear and reliable basis upon which to make a finding of air embolus in any given instance. The defence submit that the evidence fails to achieve this standard for one or both of the following reasons, namely,
a. none of the experts who have given evidence as to the general theory or diagnosis of air embolus have sufficient clinical expertise to do so; and/or
b. the research basis for air embolus as cited in the evidence is so poor or inconsistent that it fails to meet the requirements of scientific evidence capable of supporting these allegations.
5. The defence emphasise that where scientific or medical evidence is concerned it is particularly important to proceed from a basis that is solidly grounded in reliable expert experience or research and refer to dicta in paragraph 57 of the judgment of the Court of Appeal (Criminal Division) R v Holdsworth [2008] EWCA Crim 971 and the need for the court to be satisfied that there is a sufficiently reliable scientific basis for the evidence to be admitted, as stated in paragraph 11 of the judgement of that court in R v Dlugosz and Others [2013] EWCA Crim 2. That requirement is now incorporated into the Criminal Practice Direction 19A: Expert Evidence at 19A.4. The defence submit that the basis for the opinions of the experts relied upon by the prosecution to diagnose air embolus does not meet these criteria sufficiently.
6. In relation to the relevant experts, the defence submit that Dr Dewi Evans has no clinical experience of air embolus, although he is able to describe one occasion when he was aware of a baby dying from air embolus in a hospital in Swansea, or of diagnosing air embolus. As with other witnesses Dr Evans relied heavily on a paper written by Lee and Tanswell in 1989 and acknowledged the paucity of evidence on air embolus generally. They submit that he has not been consistent in his application of the characteristics to support a diagnosis of air embolus and assert that additional criteria, such as incessant or loud crying, have been relied upon to support a diagnosis of air embolus, for which there was no formal research basis; he gave two anecdotal accounts of cases where babies cried when they had received intravenous air. The defence say these cases bore no factual or clinical resemblance to the cases in this trial. They refer to the absence of research or empirical basis to account for the variation in features and, for example, an explanation as to why one baby [REDACTED] [Count 2]) could be resuscitated and another [REDACTED] [Count 1]) could not, and say Dr Evans could do no more than provide an explanation that was simply personal opinion. The defence argue that both Dr Evans and Dr Bohin have set out criteria and then adapted them as the case has progressed and as required by the exigencies of the evidence without reliance upon clinical experience or formal research, citing discolouration as an example and upon which their submissions are set out in detail in paragraphs 30-33 and 40-47 of their written submissions.
7. Emphasis is placed on the fact that, in terms of clinical experience, Dr Bohin has seen only one case of air embolus, which was at some point before 1995 and that she accepted that the available literature was “very poor on this and most of the literature is based on what researchers have seen in adults. There's very, very little on children”, and that she recognised the empirical limitations of studies on air embolus. What Dr Bohin and Dr Evans said about air in the great vessels is based upon the opinions of the prosecution paediatric radiologist, Professor Owen Arthurs. It is said that Dr Bohin has expressed opinions as to the amount of air that would lead to a fatal collapse on a limited basis of approximate and non-specific research that have varied without consistent explanations and that, despite stating that the suddenness of collapse was a feature of air embolus, she been unable to apply this principal with precision or consistency and relied on animal studies, it being unethical to conduct such studies on humans. The defence say this is no basis for forming accurate or reliable diagnoses in neonates, whatever the empirical difficulties, and submit that she has similarly varied in what she considers to be evidence of air embolus without empirical or theoretical basis and has followed this in her approach to skin discolouration. They also submit she has no clinical experience sufficient to make a diagnosis of air embolism. The imprecise and subjective character of her opinions, they argue, illustrates the lack of reliable scientific basis to support them.
8. Professor Sally Kinsey, a retired paediatric haematologist, who gave a lengthy and detailed description of how the circulation of the blood works and the mechanism of gaseous exchange as part of respiration, agreed that air embolus did not feature in her expertise and that the diagrams and explanations adduced by the prosecution that dealt with circulation were standard images of how circulation and gas exchange work, were of general application and not specific to air embolus, and that the description of skin discolouration she was familiar with was that in the paper by Lee and Tanswell. In common with all the other experts she confirmed that there is little in the medical literature regarding cutaneous features of air embolus.
9. Professor Owen Arthurs, a paediatric radiologist working at Great Ormond Street Hospital, gave evidence that the presence of post-mortem gas in a great vessel such as the aorta, which he saw on a post-mortem radiograph of [REDACTED], was an unusual finding. He explained the possible causes for such a finding and said that, absent the other possible explanations - a severe fracture under significant force, overwhelming infection of sepsis, sudden infant death or resuscitation - air embolus caused by the exogenous introduction of air was the one that was left. He accepted that air in a large vessel post-mortem itself is not diagnostic of air embolus. In expressing his opinion that the finding in this case was unusual, he relied in part on a review of cases from the files at his hospital that he conducted at Great Ormond Street Hospital. This review was conducted by Professor Arthurs as part of the preparation of his reports for this trial. The defence submit that by reference to the factors in paragraph 19A.5 of the CPD, his review/study provides a poor scientific basis for reliability for the reasons set out in paragraph 63 of their written submissions. Professor Arthurs accepted that it was not of the highest level of evidence-based medicine, but observed that sometimes this was the only available evidence. The defence submit that the study does not come close to the highest-level of evidence-based medicine: the test is not what is available, it is whether the evidence is sufficiently reliable, and the factors to consider in assessing this are set out in paragraph 19A.5. By reference to these factors, the study performed by Professor Arthurs does not, they submit, constitute a reliable basis for his opinion that the occurrence of air in the great vessel post-mortem is ‘unusual’.
10. The defence also submit that the evidence of Dr Andreas Marnerides, a paediatric pathologist and histopathologist, did not contribute to the level of knowledge establishing a reliable or applicable scientific basis for a theory of air embolism. His evidence did relate to causation on specific charges. He made reference in the case of [REDACTED] to possible air bubbles in the histopathology emanating from the lungs and from the brain, which he did not regard as proof of air embolus, but stated it was something to be taken into consideration. He accepted that in [REDACTED]’s case the pathology did not prove air embolus and that in terms of certifying the cause of death as a pathologist, it remained unascertained. He emphasised that the utility of a potential air bubble as a diagnostic tool for air embolus depended upon the overall circumstances, the evidence of clinicians and the radiology.
11. In these circumstances, the defence submit that the underlying theory of air embolus is wholly lacking in specificity or rigour, arguing that clinical experience as a basis for the opinion of the experts relied upon by the prosecution is almost non-existent, that the available research is extremely limited and does not extend to the variety and extent of expert opinion on air embolus in this case and that it does not meet the requirements of paragraph 19A.5 of the CPD and the high standard of reliability required for scientific evidence. It is for these reasons, the defence contend that the evidence of air embolus on those counts where cause is based wholly upon air embolus (Counts 1, 2, 4 and 16) is so weak, that a jury properly directed could not properly convict upon it; not least because were the deficiencies in the material as it stands at the conclusion of the prosecution case to have been capable of assessment at the outset, it is submitted that it would have been of insufficient reliability to be properly admissible. Likewise, they submit the evidence of air embolus should be withdrawn from those counts (Counts 3, 5, 12, 17 and 20) where it forms part of the medical evidence relied upon by the prosecution to support a conviction.
12. The prosecution response, as refined in oral submissions, starts from the basis that, as was accepted by the defence, air embolus can cause both fatal and non-fatal collapses of babies as well as adults. Air embolus is rare and not commonly encountered in circumstances other than in cases of high impacts or accidental medical mistake. It can be caused by the administration of air into the venous system: clinicians and nursing staff are all made aware of the risk of air embolus if air is introduced into the venous system and are trained to carry out procedures in a way that avoids the risk of accidental administration of air into the venous system. The available medical literature and research material is very limited: clinical tests cannot be carried out and the effects observed. Accordingly, knowledge, experience, understanding and experience is necessarily limited. They point to the rarity of air embolus in a clinical setting being apparent from the evidence of the experienced clinicians who have never encountered it in practice apart from the occasions in the period of this case which are alleged to be incidents of air embolus. They submit that the relative paucity of published evidence of consistent signs of air embolus and the limited descriptions in the literature and limited clinical experience do not render the evidence itself unreliable and inadmissible, rather it goes to the weight to be attached to it. Similarly, the prosecution challenge the assertion that there has been no consistency as to the discolouration claimed to be indicative of air embolus and ignores the fact that the Lee and Tanswell paper allowed for differing manifestations of discolouration, key features of which being that any discolouration (not related to sepsis) is itself unusual and transient. They submit that both Dr Evans and Dr Bohin gave clear, medically based explanations of how an air embolus causes collapse as set out in paragraphs 17 and 18 of their written submissions: it is basic physiology and they contend that both witnesses meet the qualification test to be an expert in this field and that their evidence is relevant and admissible, there being an accepted scientific basis for linking sudden and unexpected deaths to air embolus. They also emphasise the application of the principle of differential diagnosis to all the clinical and other evidence, including in the case of [REDACTED] for example, radiological evidence that is consistent with but not, on its own, diagnostic of air embolus. Once admissible as potential expert evidence, therefore, they say it is for the jury to assess the extent to which it assists them in the light of all the other evidence from the experts, clinicians and nursing staff, as well as other direct and circumstantial evidence relating to the sudden collapses of the babies in determining whether there was a deliberate harmful act by the exogenous infusion of air into the venous system causing air embolus in the case of the child being considered in these counts and whether the defendant was the perpetrator.
13. I am satisfied that there is a sufficient body of accepted expert medical opinion that the exogenous administration of air into the venous system can cause air embolus leading to collapse and potentially the death of a baby. Because of the rarity of cases in which air embolus is identified in a fatal collapse there is limited medical literature and research and the level of clinical expertise is also necessarily limited. Professor Arthurs and Dr Marnerides were conspicuously careful not to go further than their specialist expertise would permit them and emphasised any conclusions to be drawn were for those with clinical expertise. The fact that their evidence was not, of itself, diagnostic of air embolus is not determinative as to whether the evidence of clinical neonatologists is admissible. Such criticisms as are made by the defence of Drs Evans and Bohin and the bases for their conclusions are not sufficient to render their evidence inadmissible; the assessment of the validity of the criticisms and the weight to be attached to their opinions is for the jury. In the context of other circumstantial evidence, including the fact that, in the cases of two other babies not the subject of these applications someone in the NNU deliberately sought to harm them by adding insulin to their nutrition and the circumstances and coincidence of the defendant’s presence in the unit on each of the occasions of the sudden collapse of a baby, in some cases at the cot or incubator side, and her admissions, I am satisfied that the evidence sought to be excluded is admissible expert evidence for the jury to consider. I am also satisfied that, in respect of Counts 1, 2, 4 and 16, there is a body of evidence on which the jury, depending on their findings of fact and the inferences they draw, could properly come to the conclusion that the defendant is guilty. I refuse the application for those counts to be withdrawn from being determined by the jury. Similarly, I refuse the application that the evidence of air embolus should be withdrawn from the jury on Counts 3, 5, 12, 17 and 20.
The Hon. Mr Justice Goss
2 May 2023