Mingling among them on that late-winter day was a cluster of dentists who shared an interest in a budding discipline. They called it forensic odontology, a decidedly novel application of dentistry--identifying violent criminals based on the bite marks they leave on the bodies of their victims.But to create their own division within the American Academy of Forensic Sciences and gain the credibility this would bestow, 10 of these forensic odontologists were needed. Only eight were in the room.
With that, a new discipline was born, joining other more commonly known investigative tools such as toxicology and bullet matching.
Since that day in Chicago 34 years ago, bite-mark comparison has become a regular weapon in the forensic arsenal, with odontologists testifying in courtrooms hundreds of times.
They're usually brought in for cases of child abuse, rape and sex murders, where bite marks sometimes are found on victims. But concerns about forensic dentists center less on how often they testify than on how easily judges and jurors accept their opinions as scientific proof.
Courts frequently do so even though there is no accurate way to measure the reliability of bite-mark comparisons, and the method has gained acceptance without benefit of broadly reviewed research and scientific validation, elements that separate true science from guesswork.
The consequences of such subjective testimony are becoming clear. In recent years, new evidence, including DNA, has proved that even a number of the discipline's pioneers have contributed to wrongful arrests and put innocent people behind bars.
In some instances, odontologists can't even agree on the most basic issue--whether a wound is a bite mark at all.
Forensic odontology has come to represent a case study in how easily forensic science's false aura of infallibility can distort the adversarial system of American justice.
In that system, judges and juries are responsible for sifting through often-contradictory evidence. But when experts are allowed to overstate their findings and an unvalidated technique is equated with science, then the system can fail.
"I think bite marks probably ought to be the poster child for bad forensic science," said David Faigman, a professor at the University of California Hastings College of the Law and co-editor of "Modern Scientific Evidence."
It's not simply outsiders or defense attorneys asking fundamental questions. Inside the tight fraternity of odontologists, skeptics are raising concerns about bite-mark comparisons.
"Those comparisons are flawed and based on wishful thinking, as far as being conclusive scientifically," said Dr. Michael Bowers, an odontologist and lawyer who served on the examination and credentialing committee of the American Board of Forensic Odontology, the discipline's leading professional organization.
Bowers angered many of his peers when he co-wrote a controversial study in 2002 that estimated the performance of board-certified odontologists in a workshop exercise. Bowers figured that on average, they falsely identified an innocent person as the biter nearly two-thirds of the time.
Though that figure is hotly debated, even founders of the discipline express deep reservations about bite-mark comparisons.
"They have their place," said Dr. Edward Woolridge, a forensic odontologist from North Carolina. "But I know there's innocent people in jail because of bite-mark testimony."
In one notorious case, such evidence helped send Ray Krone to Death Row for the 1991 murder of a Phoenix cocktail waitress. The former postal worker spent more than three years on Death Row and seven years under a life sentence before DNA testing connected another man to the crime and exonerated Krone.
In many other cases, doubts about such testimony don't necessarily mean a defendant is innocent. But they go to an equally fundamental concern: the courts' ability to interpret and weigh forensic evidence accurately when a person's liberty is at stake.