Fallen forensics: Judges routinely allow disavowed science

BOSTON -- Two hairs that looked like the victim's; some dirt on a truck like that taken from the crime scene; a pattern on the bumper that resembled a design on the victim's popular brand of jeans.

The case against Steven Barnes in the rape and murder of a 16-year-old girl seemed circumstantial, at best.

So the guilty verdict shocked him.

"I was saying, 'This can't be happening. You can't convict somebody on similarities, perhaps or maybes,'" Barnes said.

He spent the next 20 years in prison before DNA testing exonerated him, becoming one of hundreds of people convicted in whole or in part on forensic science that has come under fire during the past decade.

Some of that science -- analysis of bite marks, latent fingerprints, firearms identification, burn patterns in arson investigations, footwear patterns and tire treads -- once was considered sound, but is being denounced by some lawyers and scientists who say it has not been studied enough to prove its reliability and in some cases has led to wrongful convictions.

Even so, judges nationwide continue to admit such evidence regularly.

"Courts -- unlike scientists -- rely too heavily on precedent and not enough on the progress of science," said Christopher Fabricant, director of strategic litigation for the Innocence Project.

"At some point, we have to acknowledge that precedent has to be overruled by scientific reality."

Defense lawyers and civil-rights advocates say prosecutors and judges are slow to acknowledge some forensic-science methods are flawed because they are the tools that have for decades helped win convictions.

And such evidence can be persuasive for jurors, many of whom who have seen it used dramatically on "Law & Order" and "CSI."

Rulings in the past year show judges are reluctant to rule against long-accepted evidence even when serious questions have been raised about its reliability:

• A judge in Pennsylvania ruled prosecutors can call an expert to testify about bite marks found on a murder victim's body, despite 29 wrongful arrests and convictions nationwide attributed to unreliable bite mark evidence since 2000.
• A Connecticut judge allowed prosecutors to present evidence a footprint was made by a specific shoe belonging to a man accused of murder, despite a 2016 finding by the President's Council of Advisors on Science and Technology that such associations are "unsupported by any meaningful evidence or estimates of their accuracy."
• In Chicago, a federal judge rejected a request to exclude testimony of government experts to describe firearm and tool-mark comparisons they performed on bullets collected at crime scenes in the trial of Hobos gang members. The judge reasoned defense lawyers were free to cross-examine the government's experts.

Two reports by scientific boards have criticized the use of such forensic evidence, and universities that teach it are moving away from visual analysis -- essentially, eyeballing it -- and toward more precise biometric tools.

But some defense lawyers fear any progress on strengthening forensic science may be lost under President Donald Trump.

In April, Attorney General Jeff Sessions announced the Justice Department would disband the National Commission on Forensic Science, an independent panel of scientists, researchers, judges and attorneys that had been studying how to improve forensic practices.