More about ‘bad science’ and miscarriages of justice. Lucia de Berk was the subject of a Dutch trial where prosecutors used certain statistics [there’s more links to discussion of statistical evidence in the BS post I’ve linked to here] as evidence against her. They also used circumstantial evidence – which was particularly popular in the days of Sacco and Vanzetti and sometimes includes ‘Conciousness of Guilt’ evidence. If I may quote from the State of Connecticut Judicial Branch, “In any criminal trial it is permissible for the state to show that conduct or statements made by a defendant after the time of the alleged offense may have been influenced by the criminal act; that is, the conduct or statements show a consciousness of guilt”. The most commonly offered types of consciousness of guilt are flight, false statements, or concealment or fabrication of evidence. Sacco and Vanzetti made false statements to the police that were included as part of the state’s case against them – almost certainly for reasons unrelated to the robberies being investigated (probably, they were hiding their political affiliations in dangerous times). The De Berk case included evidence as circumstantial and dubious as this:
On the other hand, as they revealed at her trial, Lucia did like tarot. And she does sound a bit weird in her private diary. So she might have done it after all.
[Summary of circumstantial evidence from http://www.badscience.net/?p=392]
Wikipedia expands on the circumstantial evidence with the following: “De Berk’s diary also played a role in her conviction. On the day of death of one of her patients (an elderly lady in a terminal stage of cancer) she wrote that she had ‘given in to her compulsion.’ She wrote on other occasions that she had a ‘very great secret,’ and wrote that she was concerned about ‘her tendency to give in to her compulsion.’ De Berk stated that this referred to her passion for reading tarot cards, whereas the court decided it was evidence that she had euthanized the patients.” Seems pretty tenuous to me as evidence of euthanasia – and certainly not solid enough to help convict someone of a crime that will have a significant punishment.
There was also ‘chain-link’ evidence used in this case – the ever-reliable Wikipedia [oh dear – I’ve cited Wiki twice in one blog post, I really must find better-credentialled evidence when I have the time] covers chain-link evidence and includes this: “The court then applies a so-called chaining-evidence argument. This means that if the several (attempted) murders have already been established beyond reasonable doubt, then much weaker evidence than normal is quite sufficient to establish that a subsequent eight “suspicious incidents” are indeed suspicious and in fact are murders or attempted murders carried out by de Berk. This is controversial, because for the two murders found proven by the court, many experts still did not exclude a natural cause of death.”
Bad Science and the Law are certainly connected – probably more so than had previously occurred to me. I’ve looked at abuse of statistics and recall bias so far. I haven’t even started on the role that forensic evidence plays in justice. Or mentioned the number of high profile cases where crime scenes have been compromised or evidence tampered with.
Links: Yersinia has also covered the De Berk case. The Bad Science post and the Wiki have more external links and are both well worth checking out if you haven’t already done so.