Produce crime lab error rates, some urge

The high stakes of DNA testing have prompted debate about whether the nation's crime labs should have to produce error rates. Defense experts and academics say such a statistic would provide a valid way to gauge the reliability of a lab's work. Forensic scientists in state-run and private crime labs say error rates would be meaningless.

A generic error rate for a lab doesn't tell you whether a specific DNA test is correct, said Gary Shutler, who oversees DNA testing for the Washington crime lab system.

Defense attorneys would use labwide error rates to try to undermine every DNA result, Shutler said. Even defining what type of contamination or errors should be included in an error rate would be difficult.

But some experts argue that error rates should be a factor in weighing DNA evidence in court -- something prosecutors, police and crime lab officials have a "vested interest" in avoiding.

"An error rate is an albatross around their neck," said Dan Krane, a biology professor at Ohio's Wright State University and president of a forensic consulting company. "It limits the strength of their testimony in court."

One of the best ways to determine error rates would be to use blind proficiency tests -- exams disguised as regular casework.

Right now, forensic scientists at the Washington State Patrol labs, and most other state-run crime labs, know when they are taking a proficiency test. DNA analysts must pass two of those tests each year.

Krane said open proficiency tests typically use pristine samples that bear little resemblance to complex casework.

Blind proficiency testing is recommended, but not required, by the American Society of Crime Laboratory Directors' Laboratory Accreditation Board, an organization that offers voluntary accreditation. That group advocates the blind method not as a way to determine error rates but as a more precise test of a worker's accuracy.

A decade ago, mandatory blind testing was proposed as part of the federal DNA Identification Act.

A Justice Department panel designed blind tests, tried them out and estimated it would cost $500,000 to $1 million annually for one test per lab, according to panel member William C. Thompson, a criminology and law professor at the University of California-Irvine.

The panel wound up recommending against blind testing.

"Legislators didn't want to do anything to offend law enforcement groups," Thompson said. "Law enforcement sees this as a bleeding-heart liberal attempt to give ammunition to defense lawyers."

Blind proficiency tests would be too costly to design and administer, said Barry Logan, director of the Washington crime lab system.

"We trust people doing casework to do the work professionally," Logan said.