Why her role matters
The purpose of a second-opinion expert in a criminal trial is to provide independent corroboration of the first expert’s conclusions. The jury is meant to weigh the convergence of two experts working from separate methodological frames as evidence that the conclusion is robust. For this to function as the criminal-justice system intends, the second opinion has to be genuinely independent.
Dr Bohin’s evidence was presented as this kind of second opinion. Independent review since 2024 has identified that her reading worked within the methodological frame Dr Evans had already established — same forensic-from-hypothesis approach, same absence of blinded differential diagnosis, same starting assumption that the cluster required a criminal explanation.
Professional background
- Consultant paediatrician based in Guernsey. Practises on a much smaller scale than UK tertiary NICU centres.
- Instructed as the Crown’s second-opinion expert in the Letby trial.
- Gave evidence at the original 2022–2023 trial.
Why this is a circularity concern
When a second expert is instructed to review conclusions the first expert has already reached, and adopts the same methodology the first expert used, the second opinion is not second-independent-opinion — it is same-methodology-second-clinician. The jury hears “two experts agree” and weighs that as corroboration. The reality is that the shared methodology constrains both experts to the same conclusion, because the methodology itself is the factor driving the conclusion.
The Shoo Lee Panel’s case-by-case review is the independent second opinion the criminal-justice process should have had. Fourteen senior international specialists applying a different methodology reach the opposite conclusion on the same casebook. That is what genuine independent second-opinion review looks like.
Role at trial
Dr Bohin gave evidence as the secondary prosecution paediatric expert at the 2022-2023 Letby trial, working alongside Dr Dewi Evans as the lead causation expert. Her role was to provide a second-expert opinion on the medical causation questions on each indicted count, generally substantially endorsing Dr Evans’s diagnostic conclusions. The two-expert prosecution structure is standard practice in complex Crown medical-evidence cases; the second expert’s role is to provide independent corroboration of the lead expert’s methodology and conclusions.
The substantive question for the post-conviction review is whether Dr Bohin’s opinions provided independent corroboration in the sense the Cannings principle requires (independent expert agreement that survives methodological scrutiny), or whether they operated within Dr Evans’s analytical framework without independently testing it against alternative differentials. The Shoo Lee Panel’s case-by-case findings contradict the Bohin/Evans conclusions on every indicted count.
What the post-conviction expert response says
The 14-strong Shoo Lee International Expert Panel reached unanimous case-by-case findings that the medical evidence does not support deliberate-harm conclusions on any indicted count. The Panel’s methodology applied modern differential-diagnosis frameworks: IVH, sepsis, NEC, thrombosis, twin-pregnancy complications, viral outbreak, cardiovascular instability of prematurity. The Panel’s position is, in effect, that Dr Bohin’s and Dr Evans’s methodology fell below the modern standard for neonatal-intensive-care expert evidence.
The two-expert prosecution structure
Independent commentators have noted that two prosecution experts working within a shared analytical frame is not the same evidential structure as the Cannings principle requires. Cannings (2003) established that where serious disagreement exists between reputable experts, prosecutions on medical-causation evidence should not proceed. The Crown’s case at Letby’s trial proceeded with two experts substantially in agreement; the post-conviction Panel evidence demonstrates serious disagreement between those two experts and the wider international neonatology community. Whether the Cannings principle now applies retrospectively is one of the questions the CCRC review engages.