A public inquiry into the case surrounding Lucy Letby has prompted a rare public intervention from her former counsel, who cautions that the way lessons are drawn could reshape clinical behaviour across neonatal units. Mark McDonald, who represented Ms Letby for two years, says he devoted thousands of hours to reviewing the evidence and worked with nearly 30 specialists in fields including neonatal medicine, pathology, insulin physiology and statistics. He tells colleagues and the public that he is convinced Ms Letby is innocent and that her convictions raise profound concerns about investigative and expert processes.
McDonald points to alleged failures at multiple levels — from police inquiries to expert interpretation and the criminal justice response — and stresses that these failures have broader implications for the care environment. The deaths and serious illnesses of infants on the neonatal unit at the Countess of Chester hospital remain the central facts of the case, but his review, he says, has exposed contested evidence and disputed causal conclusions that will shape how future incidents are investigated.
The core of his warning concerns workforce behaviour: if clinicians fear being singled out or criminally investigated on the basis of contested expert opinion, they may retreat from asking questions, admitting errors or escalating concerns. Such a shift, he argues, could foster defensive practice. That prospect, he adds, risks undermining the very improvements in safety and transparency that public inquiries typically seek to promote. He encapsulated that risk starkly: “a defensive staff is dangerous for everyone.”

