The Jolly Contrarian on Crime and Punishment

In his summing up, Mr Justice Goss instructed the jury that they did not need to be sure precisely how Ms. Letby murdered the infants, as long as they were sure she did:

“If you are sure that someone on the unit was deliberately harming a baby or babies you do not have to be sure of the precise harmful act or acts; in some instances there may have been more than one. To find the defendant guilty, however, you must be sure that she d...

Take the following hypothetical scene, which describes Lucy Letby’s experience at the Countess of Chester Hospital:

Internal investigation

A hospital experiences a cluster of deaths and collapses materially in excess of its usual rates for such events.

Staff notice a particular nurse was present during an abnormal proportion of the collapses.

Concerned at the possibility of foul play, hospital management investigates the collapses, foc...

A leopard goes to the doctor.“Doc,” he says, “You gotta help me. Whenever I look at my wife, I see spots.”The doctor looks at him for a minute and says, “Well, what do you expect? You’re a leopard.”“I know that, Doc. But I’m married to a zebra.”

Healthcare serial murder enquiries are unusual in that they generally start without specific evidence of wrongdoing as such. Suspicion generally arises from an unusually large cluster of une...

In his book The Black Swan, Nassim Nicholas Taleb presents the “ludic fallacy”: the mistake of applying unvarnished theoretical probabilities to real-world scenarios.

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Here is his example:

You have a fair coin which, on the last 99 flips, had come up “heads”. Assuming it is a fair coin, what is the probability of it coming up “heads” on the 100th flip?

Professor of statis...

Prelude: A daycare centre in New Zealand

Peter Ellis was a childcare worker in Christchurch, New Zealand. A creative, flamboyant and somewhat uninhibited character, Ellis loved his job, put a lot of energy into programme planning, and would entertain children with elaborate puppet shows and somewhat provocative productions, sometimes to the point of being “risqué and outrageous”. Ellis had worked at the daycare centre for several ye...

Show me a man who believes in conspiracy theories and I’ll show you someone who has never organised a surprise party.

—Lee Harvey Oswald.

The constant presence

Ordinarily, when a defendant appears on 22 counts of things like murder, there is a wealth of compelling evidence: eyewitnesses, fingerprints, incriminating forensics and related corroborations that point not just to murder, but to the defendant, specifically, committing each o...

The test results showing that insulin had been given to them was the only piece of concrete evidence of criminality throughout the whole of the prosecution’s case. It was the closest thing they had to a smoking gun and became the keystone for their case as a whole.

Johnson’s argument ran that if the jury could agree that Letby had deliberately poisoned two babies, they could also reasonably conclude that she had harmed others using ...

“Lucy Letby Conspiracy Theorists are Wrong”, Liz Hull, Daily Mail, July 5, 2024.

R v Letby, Court of Appeal Judgment, 2 July 2024.

Rachel Aviv’s, New Yorker investigation of 13 May 2024.

Lucy Letby: initials of babies noted in diary on dates of alleged attacks, court told, The Guardian, 17 April 2023.

Serial murderers of any kind are vanishingly rare in Britain. Wikipedia lists fifty-five, since 1600. But so are miscarriages of justice. Wikipedia lists fifty-four, since 1255.

Both narratives are highly improbable. Of all the explanations we might offer for the unusual spike of incidents in 2015 and 2016, as a matter of “prior probabilities” they are the least plausible: all else being equal, it is highly unlikely there was a seri...

The collection of biases and cognitive gin-traps that can lead prosecutors — those who “prosecute” a particular theory of the world — to stick with it, however starkly it may vary from available evidence and common sense.

So named because it is often literal prosecutors, of crimes, who suffer from it. This kind of tunnel vision has led to notorious miscarriages of justice where innocent people come to be convicted notwithstanding cl...