In Family Court / Child Protection cases resting on medical evidence disputed by accused parents, decisions are made on the balance of probabilities. One can understand that where a child's future safety depends on the right decision, erring on the side of caution is a preferable outcome. Often these cases don't go to criminal court to be tested to a point if reasonable doubt.
In this case the balance of probabilities approach seems to have crossed over.
Expert witnesses are a small pool. Some have built entire careers and reputations on "saving children" . Since Roy Meadows, it's not surprising that fewer professionals want to put themselves in that spotlight. The consequences of getting it "wrong" are a huge burden either way.
There are dogmas surrounding the diagnosis of child abuse via medical evidence because obviously testing most theories in that field would be harmful and unethical.
There is a heavy reliance on psychology because it's human nature to want to understand "why" someone deviates so far from the normal behaviour of a caregiver of a children. Sometimes it's obvious. Stress, addiction, a history of anti-social behaviour etc. Sometimes it's not. And there lies the danger. There is a possibility that the certainty that someone has done something so dreadful in the minds of professionals turns into a zeal to convince the suspect of their guilt even if they steadfastly defend themselves. Psychological pressure of that nature breaks people.
Why didn't Lucy Letby get better expert witnesses? Or have the one prepared to testify actually do so?
Possibly because the legal team, well aware of the adversarial nature of the courts knew how things were going to pan out regardless. And she had to take their advice.
I also think that criminal court is not the arena for dealing with complex medical evidence. Where there is doubt, other mechanisms should be in place to prevent the suspect from doing further harm - suspension, house arrest, whatever - until all avenues have been exhausted, which they clearly haven't in this case. And then the question of punishment can be addressed.
It's a dangerous precedent to say it doesn't matter if medical evidence is contentious because we've got our baby killer bang to rights because she was there. It could happen to anyone. Believe me, I know.