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The Power of Science in Achieving Justice

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Join us for an upcoming strategy session so we can begin to structure our campaign to secure a new trial for Lucy Letby.  We will meet over zoom and develop key roles and approaches to achieve justice for Lucy.

To be determined

Join us for a lively discussion with leading experts in the field of science and justice. Learn about the latest developments and how they impact the criminal justice system.

To be determined

Expert Witnesses 
Challenging reliability 

Following the verdicts, it was revealed that Lucy Letby's Barrister, Benjamin Myers, KC, sought to have the expert witness evidence of Dr Dewi Evans dismissed from the case.  The Judge presiding over the case denied the barrister's application stating that it is for the jury "to determine, as with any witness, his reliability, having regard to all the evidence in the case."

This decision to permit Dr Evans evidence is controversial, as permitting the jury to evaluate expert witness testimony is distinct from that of a general witness.  It was previously found that, “In determining the issue of admissibility, the court must be satisfied that there is a sufficiently reliable scientific basis for the evidence to be admitted. If there is then the court leaves the opposing views to be tested before the jury.” R v Dlugosz [2013] EWCA Crim 2, [2013] 1 Cr App R 32 at [11]”

At issue is the reliability of the evidence on a scientific basis.  It is evident that none of the normal practices used to determine air embolism as a cause of death were applied by Dr Evans, and the one publication he referred to does not relate to air embolism through ambient air entrainment in the vasculature.  Dr Evans determined that the infants died due to air embolism by referring to a 1989 research paper, which described gas embolism, due to the usage of high ventilation pressures which is a practice no longer applied to neonates.  None of the findings on autopsy suggest the children died due to air embolism.

It is apparent that a crucial element in the Lucy Letby case is the reliability of the original investigation.  It is of great concern that Dr Evans conducted the investigation with the assistance of the consultants who were present on the ward at the time of death, and where, in any other setting, such individuals should have been treated as suspects.  A further factor is whether Dr Evans was qualified to conduct any investigation given that he is neither a forensic scientist, nor pathologist.  Dr Evans has no formal training or background in the principles of scientific research.  It is highly irregular for a group of medical doctors to play a primary role in carrying out a criminal investigation.  In most other jurisdictions such activity would not constitute an independent investigation.

Regarding the issues surrounding the reliability of expert evidence in criminal courts in England and Wales, the Department of Justice stated:

"...there is no robust estimate of the size of the problem to be tackled – either in terms of the number of cases where unreliable expert evidence is adduced, nor in the impact this has in terms of subsequently quashed convictions.”


UK Ministry of Justice (2013)

Government Response to Law Commission Report on Expert Evidence

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