The Frontal Cortex

Bad Jury Verdicts

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.)


  1. #1 Rose Colored Glasses
    July 23, 2007

    Juries are also selected for their inclination to convict.

    The whole point of ‘voir dire’ is to bias the jury.

    Look at the problem logically. We start with a dozen random jurors. How can that be unfair? Why would we let the one side and then the other cherry-pick through the candidates? If the pickers are evenly matched, which should be a rare event, there should be no effect, and so, generally, the better picker would gain the upper hand, biasing the jury. So the whole story on its face is absurd.

    Why would the defense and prosecution both defend the process? Because it makes prosecution much more likely that exoneration, which fact benefits both sides. It makes it easier for the prosecution to get convictions, and artificially inflates the value — and thus the earning power — of the defense.

    A truly fair jury would not favor either side. Each juror would have veto power over the prosecutor’s charges. That would be 12 independent tests for the prosecutor to pass. A single failure, and the accused goes free.

    A truly fair jury would be one where the prosecution knows nothing about them. He can’t know their prejudices, their attitudes, their trusting natures — or their skepticism.

    Nobody can do better than a random jury of anonymous people.

    But the prosecution, and the defense, and the judge, will not trust to the luck of the draw. All three parties collude in cherry-picking the jury.

    So, why wouldn’t we expect deliberately biased juries to act like they’ve been deliberately biased?

  2. #2 hidrolik mantar
    March 7, 2009


  3. #3 krom kapli
    March 7, 2009


  4. #4 Best Watches
    February 28, 2010

    Very scary to think of being punished for something you didn’t do, at least time will fly when wearing a new mens watch in your prison cell.

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