Prosecution dog put innocent people behind bars (and other bogus 'evidence' does the same)

William Dillon spent 27 years behind bars for a crime he didn't commit. Wilton Dedge spent a similar stretch behind bars before finally being exonerated. Juan Ramos was sentenced to death before being freed from prison over a crime he didn't commit. The three men are linked not just by their innocence, but by the role played in their cases by dog handler John Preston, a one-time Pennsylvania state trooper, and his amazingly talented dog, Harass II. Preston was only one of many "scientific" experts later exposed as a fraud, some of whose victims may still wait to be revealed.

Scott Maxwell of the Orlando Sentinel has the details regarding Preston and the wreckage he left behind. But the fact that Preston and his "wonder dog" were so relied upon by prosecutors and courts until exposed in the media and humiliated by one judge demonstrates just how much suspension of disbelief (or outright dishonesty) is behind the acceptance of "forensic science" that too often turns out to be either poorly applied -- or even pure hocum.

Reason magazine's Radley Balko has made justified waves in recent years by exposing the nonsense disguised as medicine peddled by Dr. Michael West, a dentist who offered scientifically implausible evidence of guilt (in several cases, of defendants later proven innocent), based on his exclusive bite-mark "technique."

Balko was also largely responsible for (hopefully) ending the career of the notorious Dr. Steven Hayne, a medical examiner without credentials who seemed to customize his testimony to meet the needs of prosecutors.

But it's not just corrupt individuals who deserve skepticial consideration -- so do whole areas of forensic "science." Drug testing, for instance, is a highly subjective "science" that has a lot to do with the skill -- and honesty -- of technicians. It's not at all uncommon for ordinary soap to test positive for illegal intoxicants.

A report on the state of forensic medicine for the National Academies of Science concedes that "The fact is that many forensic tests -- such as those used to infer the source of toolmarks or bite marks -- have never been exposed to stringent scientific scrutiny."

Overall, says the report:

[I]n some cases, substantive information and testimony based on faulty forensic science analyses may have contributed to wrongful convictions of innocent people. This fact has demonstrated the potential danger of giving undue weight to evidence and testimony derived from imperfect testing and analysis. Moreover, imprecise or exaggerated expert testimony has sometimes contributed to the admission of erroneous or misleading evidence.

"Faulty" science has to include the evidence of dogs, which have become so ubiquitous in recent years because of their supposed ability to connect defendants to crime scenes, or to simply detect forbidden substances.

But, despite the legendary power of their noses, canine-based evidence has to be taken with a grain of salt. For starters, dogs' "testimony" is highly dependent on the word of their handlers. In fact, there's no standard way for a dog to tell us that something has been detected. Some dogs just sit, others jump up and bark -- interpretation is in the eye of the handler.

Dogs, also, are notoriously easy to manipulate, since they develop close bonds with their handlers. For a 2004 report on the unreliability of detection dogs, Auburn University professor Larry Myers, a leading expert on canine detection programs, told CBS News, “They can tell you that something's there, that's not there, simply to get praise, to get food, to get whatever they're working for.”

Through improperly training his dogs, or simply lying about their alerts, it was easy for John Preston to manufacture evidence of the guilt of innocent men.

But fallibility can be as dangerous as fraud. The U.S. Court of Appeals for the Eighth Circuit ruled in 2007 that canine testimony was acceptable in a case where the dog was only 54% accurate.

How many years of prison time are we willing to let ride on a 54% accuracy rate?

None of this is to say that forensic science is worthless. Properly used and understood it's absolutely necessary. After all, William Dillon and Wilton Dedge were freed of the shackles placed on them by bogus canine testimony because of the more rigorous standards set by DNA evidence.

But presenting fallible and sometimes fraudulent evidence as if it's beyond question runs the risk of discrediting good science along with the bad. The damage done by the John Prestons of the world can only be undone if we treat science as an imperfect part of an imperfect world -- not as the magic so-often peddled by charlatans.