Monday, August 4, 2008

The evidence does not lie – or does it?

Will exposes signal end to blind reliance on "science"?

CSI trumpets the notion that evidence does not lie.

But critical news stories may be signaling the end of uncritical evidence of this dubious tenet.

Take this introduction to a 2007 Denver Post series, “Trashing the Truth”:
Virtually every night on prime time, TV detectives pluck tiny samples of DNA from clothes, carpets, and even car tires, test it and nail the bad guy, all in one episode. But in real life, DNA samples … get mishandled with impunity…. Law enforcers have won passage of laws letting them off the hook for perjuring evidence on which people's lives and liberties hinge. The result: Killers walk…. These are the stories you won’t see on CSI. In cases around the country, the truth is being trashed.
As the Post series meticulously documents, contrary to the portrayals on fictional crime dramas and by expert witnesses for the prosecution, evidence rooms are characterized by "darkness and disorder" and the accidental and intentional destruction of tens of thousands of potentially important DNA samples.

Forbes magazine recently echoed the alarm, in an opinion piece "What's wrong with CSI: Forensic evidence doesn’t always tell the truth" by Roger Koppl, an economics professor and director of the Institute for Forensic Science Administration:
Forensic evidence is foolproof, right? It's how those clever cops on CSI always catch the killer. DNA evidence springs innocent men from prison. Fingerprints nab the bad guys.

If only forensics were that reliable. Instead, to judge by the most comprehensive study on the reliability of forensic evidence to date, the error rate is more than 10% in five categories of analysis, including fiber, paint and body fluids. (Meaning: When the expert says specimen X matches source Y, there's a 10% probability he's wrong.)
Even Government Technology, hardly a muckracking journal, is calling for reform. GT's July 9 story, "Police Crime Labs Struggle with Funding, Training and Bias Issues," focuses on the Houston crime lab, where an investigation found "hundreds of cases where incompetence, inadequate training and resources, lack of guidance and even intentional bias on the part of a crime lab - which is not independent from the HPD - contributed to mistakes."

The problems "may be inherent in crime labs across the country," the GT article concludes, citing reports of DNA testing errors nationwide - in Washington, North Carolina, California, Minnesota, Pennsylvania and Nevada.

Problems obvious

When a TV station in Houston looked into that city's crime lab operations back in 2002, the problems were obvious to an independent forensic expert:

"They weren't running proper scientific controls. They were giving misleading testimony. They were computing their statistics incorrectly - in a way that was biased against the accused in many cases,” said forensic expert William Thompson of UC Irvine.

Errors favor prosecution

Most troublingly, the errors are not random - they almost invariably favor the prosecution. Thompson identified a "team culture" mentality in the crime lab, a mentality that may lead technicians to bend the evidence against defendants in court.

Journalist Scott Henson at Grits for Breakfast has been keeping up with this issue for several years, publicizing not only DNA evidence scandals but also problems with other supposedly neutral scientific technologies in the criminal justice system. These include false-positive breathalyzer tests for drunk drivers and urinalyses that routinely send probationers and parolees back to jail.

Indeed, Henson says it was the 25% rate of false positives in breathalyzer tests that first turned his attention toward "the reality that accuracy appears optional in many forensic science endeavors, with error rates of 10% or more routinely accepted in a variety of forensic fields."

What’s the solution?

Most outsiders agree that a first step toward improving the abysmal state of scientific evidence collection and analysis is outside oversight.

Beyond that, Roger Koppl, the economics professor writing for Forbes, has some other interesting ideas, primary among them opening the labs to free market forces:
The core problem with the forensic system is monopoly. Once evidence goes to one lab, it is rarely examined by any other. That needs to change. Each jurisdiction should include several competing labs. Occasionally the same DNA evidence, for instance, could be sent to three different labs for analysis.

This procedure may seem like a waste. But such checks would save taxpayer money. Extra tests are inexpensive compared to the cost of error, including the cost of incarcerating the wrongfully convicted. A forthcoming study I wrote for the Independent Institute (a government-reform think tank) shows that independent triplicate fingerprint examinations in felony cases would not only eliminate most false convictions that result from fingerprint errors but also would reduce the cost of criminal justice if the false-positive error rate is more than 0.115%, or about one in a thousand.
Other reforms suggested by Koppl and others include making crime labs independent of law enforcement, requiring blind testing, and giving the defense the right to its own forensic experts:
When crime labs are part of the police department, some forensic experts make mistakes out of an unconscious desire to help their "clients," the police and prosecution. Independence and blind testing prevent that. Creating the right to a forensic expert for the defense would help restore the imbalance in scientific firepower that too often exists between prosecution and defense.
The Denver Post series, Trashing the Truth, includes the following segments:
  1. Bad faith difficult to prove: Through carelessness or by design, tiny biological samples holding crucial DNA fingerprints often disappear on authorities' watch. Innocent people languish in prison, and criminals walk free.
  2. Room for error in evidence vaults: In some evidence rooms, chaos and disorganization make searches futile. Others are purged of valuable DNA samples, leaving cases unsolvable.
  3. Missing rape kits foil justice: Rape kits routinely vanish, unfuriating victims and prosecutors alike. Even when evidence is intact, laws can keep suspects like William Harold Johnson walking free in our midst.
  4. 14 years later - Tell my story: Floyd Brown has an IQ in the 50s. Its authenticity in doubt, his confession to a 1993 murder has him locked up indefinitely in a North Carolina mental hospital. A bloodstained stick that could settle his innocence or guilt has vanished.

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