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When Science Kills

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More must be done to improve the use of science in the courtroom

"Most lawyers are terrified of science. So are judges. So are jurors." - M. Chris Fabricant, Director of Strategic Litigation, The Innocence Project

“No matter how many times Bayesian statisticians try to explain to me what the prosecutors fallacy is I still do not understand it and nor do I understand why there is a fallacy” - one of the UK’s most eminent judges (from

"You've seen one dead girl with bites on 'em, you've seen 'em all" - Michael West, disgraced forensic dentist

"It is quite clear therefore that outside the field of DNA (and possibly other areas where there is a firm statistical base), this court has made it clear that Bayes theorem and likelihood ratios should not be used."

"Sometimes the "balance of probability" standard is expressed mathematically as "50 + % probability", but this can carry with it a danger of pseudo-mathematics, as the argument in this case demonstrated. When judging whether a case for believing that an event was caused in a particular way is stronger that the case for not so believing, the process is not scientific (although it may obviously include evaluation of scientific evidence) and to express the probability of some event having happened in percentage terms is illusory. "

"The chances of something happening in the future may be expressed in terms of percentage. Epidemiological evidence may enable doctors to say that on average smokers increase their risk of lung cancer by X%. But you cannot properly say that there is a 25 per cent chance that something has happened: Hotson v East Berkshire Health Authority [1987] AC 750. Either it has or it has not."

"Imagine being in jail where everyone thinks you are the scum of the earth, the lowest human being that walks the earth. The thick end of it is that she lost five to six years of her life in what was state-sponsored torture." John Batt, a solicitor and writer who was a member of Mrs Clark's defence team,

"Sally Clark, the solicitor wrongly convicted of murdering her two baby sons, was found dead by her family at her home yesterday"

"I think justice can be served without a statistician"

"Exactly. A statistician in a case like this is purely white noise"

"Proper use of probabilistic reasoning has the potential to improve the efficiency, transparency and fairness of criminal trials by enabling the relevance of evidence – especially forensic evidence – to be meaningfully evaluated and communicated. If more widely and effectively used, it could lead to fewer cases being revisited by the Court of Appeal."

"..when you have eliminated the impossible, whatever remains, however improbable, must be the truth" (Sherlock Holmes in The Sign of the Four, ch. 6, 1890)

"To change people's hearts and minds about criminal justice, people really have to care more about accuracy and reliability than about retribution" - Peter Neufeld, Co-Founder, The Innocence Project

Court of Appeal bans Bayesian probability (and Sherlock Holmes)

Keith Harward (exonerated through DNA). DNA excluded Harwood. Next step was to do CODIS (Combined DNA Index System) search. Ran the profile through the data bank and got a hit - Jerry Crotty. Dana Delger; Keith Harward; John Prante.

How a Bogus Bite Mark Sent Charles McCrory to Prison. Bite-mark analysis was key to Charles McCrory's 1985 conviction. The science has since been debunked — so why is McCrory still in prison?

The American Board of Forensic Odontology (ABFO) developed a study. First step. 100 cases where there had been bite mark evidence. Sent to board certified diplomates who were asked whether the bite mark was human, not human, or suggestive of human. Tried to look at level of agreement among diplomates. President (Dr Freeman) thought study would prove the first step i.e. that there was a high level of agreement. Result? Some of the cases one third each! After the study, Dr Freeman decided he was no longer going to do bite mark analysis for the prosecution.

The views expressed in this communication are those of Peter Elston at the time of writing and are subject to change without notice. They do not constitute investment advice and whilst all reasonable efforts have been used to ensure the accuracy of the information contained in this communication, the reliability, completeness or accuracy of the content cannot be guaranteed. This communication provides information for professional use only and should not be relied upon by retail investors as the sole basis for investment.

© Chimp Investor Ltd

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