Beyond Reasonable Credence

Body Mapping and Blood Splatter

Life imitating entertainment.  That's what is happening in court rooms everywhere these days.  Turn on the TeeVee on virtually any night and you will have three or four forensic crime shows to watch.  Within short order you will become a relative expert on data matching, blood splatter patterns, bullet rifling, and finger-printing.  It's all comforting because the innocent are always vindicated, the guilty are always caught, and it is hard-evidence, fact-based.  Science, after all, gives certainty.  Many would say, the only certainty in this mad world.

Ah, sorry.  It all a figment of the febrile imagination of TeeVee moguls and their minions.  But it is having a  significant impact on law courts and juries.  It's got the Aussies worried.

Gary Edmond, a University of NSW law academic who has researched expert evidence over the past four years, wrote in a paper in the Australian Journal of Forensic Sciences earlier this year: ''A good deal of the opinion evidence produced by forensic science and medicine appears to be unreliable or of unknown reliability, and obtained in conditions that make few, if any, sustained attempts to minimise known risks and dangers.''

In 2009, the peak body of US scientists, the National Academy of Sciences, released a report that found only DNA testing among the broad range of forensic sciences was sufficiently grounded in science to regularly and accurately identify a suspect. (And even then serious concerns remain about DNA evidence, including the ability to wrongly convict people on tainted or rigged samples).

The flip side is that almost every other field of forensic science - the science used by expert witnesses in court to establish guilt or innocence - does not have the same level of scientific rigour.  The pall cast by the report hangs over areas that have developed a TV-inspired mythos of infallibility: blood spatter examinations, bullet rifling and even fingerprinting.

''What we see on TV is a super science,'' says Richard Kemp, a University of NSW psychologist who is studying the way juries react to expert evidence.  ''And that is so at odds with the reality of what is occurring. You want scientists doing science, which on the whole is really dull. It doesn't make for good TV.''

Convictions are starting to fail in Courts of Appeal where the conviction has been based on speculative forensic "science".  The SMH article reviews one such appeal:

When a sledgehammer-wielding robber broke through the front doors of the Willoughby Hotel early one January morning in 2008, his balaclava-clad image was captured by a security camera.  Fewer than 30 minutes later the same robber, still bearing a sledgehammer and still wearing a balaclava, was photographed stealing just over $13,500 at the P.J. Gallagher's Irish Pub in Drummoyne.

Twenty-three months later, a Tempe man, Raymond George Morgan, was found guilty in the District Court of two counts of robbing more than $58,500 in the heists and sent to jail.  The security cameras helped convict Morgan of the crimes when an expert witness linked him to the scene of the crimes through a science used in court known as ''body mapping''.

Earlier this month Morgan won a retrial because the expert's evidence was rejected by the Court of Criminal Appeal. The court found the body mapping was ''simplistic'' and did not use one measurement. In the appeal court's view, the ''science'' of body mapping used in the case of Morgan was wearing no clothes.  So much for all those toned and svelte CSI forensic investigators running around on television each week.

Morgan's robbery convictions have been overturned at a time when increasing concerns are raised about ''junk science'' appearing before the courts: unreliable expert evidence leading to contaminated criminal trials.  At its worst, such evidence could result in innocent people being sent to jail. At the very least, such evidence could tilt trials unfairly.

We live at a time when Man is demanding epistemological certainty.  Infallibility is an inescapable concept and creatures cannot function without it.  Either they will submit to the infallibility of God Himself, or they will endeavour to manufacture it amidst the endeavours of the creature or the creation.  

The over-egged claims of the TeeVee forensic shows are just one more example.  Yet they are deceptively potent--because sooner or later viewers end up on a jury where they will be required to decide guilt or innocence on the basis of forensic science.  If they are predisposed to believe that the science is always infallible, always right injustice and false convictions could become endemic.