In recent episodes of Double Jeopardy, Ken Macdonald and Tim Owen have focused on the massive publicity surrounding the trial of Lucy Letby, and on the barrage of criticism of  the expert medical evidence used by the prosecution to prove that babies were deliberately harmed by Lucy Letby, rather than dying of natural causes in circumstances where premature babies are uniquely vulnerable to medical crisis.

In this episode Ken and Tim are joined by Dr Richard Latham, an NHS consultant forensic psychiatrist and expert witness who has huge experience of complex psycho-legal issues in criminal trials. In their discussion, they look at the duties and responsibilities of medics and scientists giving evidence in criminal proceedings.

How is a diagnosis of mental disorder or mental illness made where intent is a key issue? What is required for establishing the partial defence to murder of diminished responsibility, and how does it differ from insanity? What are the professional and ethical duties that  apply to experts instructed by the defence or the prosecution? And can it ever be appropriate for experts to speak out about a case they weren’t involved in, when they haven’t seen all the case materials?