A truly depressing analysis of the justice system (Times $elect):
Brandon L. Garrett, a law professor at the University of Virginia, has, for the first time, systematically examined the 200 cases, in which innocent people served an average of 12 years in prison. In each case, of course, the evidence used to convict them was at least flawed and often false — yet juries, trial judges and appellate courts failed to notice.
“A few types of unreliable trial evidence predictably supported wrongful convictions,” Professor Garrett concluded in his study, “Judging Innocence,” to be published in The Columbia Law Review in January.
The leading cause of the wrongful convictions was erroneous identification by eyewitnesses, which occurred 79 percent of the time. In a quarter of the cases, such testimony was the only direct evidence against the defendant.
Faulty forensic evidence was next, present in 55 percent of the cases. In some of those cases, courts put undue weight on evidence with limited value, as when a defendant’s blood type matched evidence from the crime scene. In others, prosecution experts exaggerated, made honest mistakes or committed outright fraud.
Most of the forensic evidence involved problems with the analysis of blood or semen. Forty-two cases featured expert testimony about hair, an area that is, Professor Garrett wrote, “notoriously unreliable.”
These dismal findings wouldn’t surprise a psychologist. It’s a truism of psych 101: humans are heroically bad Bayesians, plagued by dishonest memories, and irrationally swayed by “expert” testimony and emotional outbursts. In other words, we are terrible jurists. If I’m ever charged with a crime, get me a jury full of Vulcans, or at least a jury foreman who’s an economist.
Given our imperfect mind, it’s crucial that we take steps to prevent, or at least discourage, some of these mental mistakes from affecting the outcome of trials. I’ve blogged about this before, but there are some simple steps that can be taken, such as doing away with the police lineup. (The standard lineup encourages false eyewitness testimony.)