Inside the Letby Defense

In this episode of All Things Conflict, I sat down with barrister Mark McDonald, who is currently leading the legal team for Lucy Letby.

Lucy Letby was convicted of the murder and attempted murder of multiple infants at the Countess of Chester Hospital, a case that has shocked the UK and become one of the most controversial criminal trials in recent British history.

Because of the gravity of the case and the strength of public feeling around it, I wanted to create a space for a careful and open conversation. My aim in Justice Redesigned has always been to explore how our justice systems work, where they succeed, and where they may fail. Speaking with Mark gave me an opportunity to examine the legal questions that remain around this extraordinary case.

Why This Conversation Matters

When Mark and I began talking, one thing became immediately clear: challenging a conviction of this scale is incredibly difficult.

Mark explained that after Letby’s conviction and life sentence, the legal avenues available to her are extremely limited. Appeals are tightly constrained, and once they have been exhausted, the only realistic route left is through the Criminal Cases Review Commission (CCRC).

The CCRC exists to investigate potential miscarriages of justice and can refer cases back to the Court of Appeal if compelling new evidence is found. But the threshold for doing so is very high.

The Question of “New Evidence”

One of the key issues Mark discussed was the requirement for fresh evidence.

In legal terms, this means evidence that was not available at the time of the original trial and could potentially have influenced the jury’s decision.

Mark believes that new scientific and medical analysis may meet this threshold. His team is currently reviewing expert opinions and evidence that they say could challenge some of the conclusions presented during the trial.

Concerns About Medical Evidence

A significant part of our conversation focused on the scientific evidence used during the trial.

Mark raised questions about the interpretation of medical findings, particularly claims that some babies died from air embolisms. According to him, his team is examining whether those conclusions were supported by clear post-mortem evidence and whether the medical testimony presented to the jury was as definitive as it appeared.

Listening to this, I was reminded of how complex scientific evidence can become when it enters the courtroom, especially when juries are asked to weigh highly technical expert opinions.

The Problem With Statistics

Another issue we explored was the statistical argument presented during the trial.

Much attention was given to what became known as the “Letby Chart,” which showed that Letby was on duty during each of the incidents involving the babies.

Mark argued that some statisticians have criticised this as a potential statistical fallacy, suggesting that the chart may not have adequately accounted for factors such as shift patterns, staffing structures, or natural fluctuations in mortality rates within hospitals.

For me, this raised a broader question: how easily can statistics be interpreted in ways that appear conclusive but may oversimplify a complex reality?

The Role of Defence Lawyers

Our conversation also touched on something more personal.

Mark spoke candidly about the hostility that defence lawyers sometimes face when representing people accused of serious crimes. Cases like this can provoke enormous public anger, and lawyers themselves can become targets of that emotion.

But as we discussed, the right to a defence is not optional, it is fundamental to the rule of law. Ensuring that every person receives a fair trial, regardless of the accusations against them, is one of the core principles of any functioning justice system.

What Happens Next

Looking ahead, Mark believes the next 12 to 24 months will be crucial.

His legal team is working to compile new expert evidence and scientific analysis that could form the basis of an application to the Criminal Cases Review Commission. If the Commission believes the case meets its criteria, it could refer it back to the Court of Appeal for reconsideration.

Whether that happens remains to be seen. What is clear, however, is that the case continues to raise difficult questions about science, evidence, and how the justice system responds when doubt is introduced after a conviction.

Why I Wanted to Have This Conversation

For me, conversations like this are not about taking sides. They are about understanding the processes that underpin our justice system and asking whether they are robust enough to withstand scrutiny.

The Lucy Letby case has already left a deep mark on the public consciousness. But as Mark and I discussed, the search for truth in complex legal cases rarely ends with a single verdict.

And if there is one principle that must always remain intact, it is this: justice systems must always be open to review, challenge, and the possibility that they can get things wrong.

🎧You can listen to the full episode of All Things Conflict, to hear the complete conversation with Mark McDonald and explore the legal and scientific questions surrounding the Lucy Letby case.