More Dire Abuse of Stats in Court

CHARLES RICHARD SMITH has learned the hard way that you can prove almost anything with statistics. In 2009 a disputed statistic provided by a DNA analyst landed him with a 25-year jail sentence.

Smith was convicted of a sexual assault on Mary Jackson (not her real name) in Sacramento, California, which took place in January 2006. Jackson was sitting in a parking lot when a stranger jumped into her truck and made her drive to a remote location before forcing her to perform oral sex on him. When police arrested Smith and took a swab of cells from his penis, they found a second person’s DNA mixed with his own.

The DNA analyst who testified in Smith’s trial said the chances of the DNA coming from someone other than Jackson were 1 in 95,000. But both the prosecution and the analyst’s supervisor said the odds were more like 1 in 47. A later review of the evidence suggested that the chances of the second person’s DNA coming from someone other than Jackson were closer to 1 in 13, while a different statistical method said the chance of seeing this evidence if the DNA came from Jackson is only twice that of the chance of seeing it if it came from someone else.

http://www.newscientist.com/article/mg20727743.300-how-dna-evidence-creates-victims-of-chance.html?DCMP=OTC-rss&nsref=online-news

This is a US case and the guy is still in jail.  Given that the assailant was with the victim for so long, one has to wonder what the other evidence was and what the case was all about.  The guy may be innocent, or there may be a sound case against him on other evidence.

It turns out the actual stats were never presented in court, making one wonder again about the quality of defence lawyers, and dire bias in prosecutions that just should not be there.  All so bad that a rapist may go free because of a ‘cock-up’, or yet again faith in our legal system (US this time) is in a mess.  Underlying all this is the way ‘statistics’ are used in our society in a manner so far detached from reality.  Forensic scientists risk becoming the new strawmen – these guys used to stand outside our courts with straw in their socks to indicate their evidence could be bought by the highest bidder.

The indications from this and other miscarriages is that there may be a severe underlying bias in our legal systems against any poor sod locked up.  We may be heading towards a really rotten situation in which the law moves towards acquittal when chummy can show tests that ‘might’ have shown his ‘innocence’ were not done.  The science in the above case is well established – it may be time to start locking up the ‘new straw men’ and lawyers using them and judges allowing them.  The charge might be ‘incompetent perjury’.

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