Law professor discusses flaws in police tactics

David Harris has seen what can happen when law enforcement embraces science. Now he wants to see…David Harris has seen what can happen when law enforcement embraces science. Now he wants to see what he called a traditionally stubborn community embrace change on a national level.

In a lecture on his new book Failed Evidence: Why Law Enforcement Resists Science, the Pitt law school professor and associate dean for research said on Wednesday that law enforcement agencies across the United States actively resist procedural changes in policing and prosecuting techniques that would drastically reduce faulty convictions.

Speaking to a group of about 30 listeners that included students, professors and a local detective, Harris told the crowd that everything from the way police collect evidence, to the way prosecutors display evidence, to what judges allow juries to see in the courtroom, must change to protect the falsely accused.

Chief trial deputy at the Allegheny County district attorney’s office Dan Fitzsimmons and Allegheny County Medical Examiner Karl Williams were also at the lecture, and they offered criticism and alternative views on Harris’ argument.

Harris said that when it comes to eyewitness identification, interrogation of suspects and forensic science, law enforcement has not integrated well-established scientific fact into routine police work.

“The reaction that I found was that most of law enforcement — I want to stress most, not all, because there are leaders in this business that have caught the science train… — are not interested in calibrating their practices,” Harris said.

Since the inception of DNA evidence in the U.S. in 1989, there have been 297 post-conviction exonerations because of the new science.

Harris said 72 percent of these cases involved faulty eyewitnesses, 50 percent had faulty forensics and 27 percent involved false confessions.

Many cases, Harris said, involved two or more of these mistakes, which is why the percentages overlap, resulting in more than 100 percentage points.

Fortunately, Harris said, science has also provided answers to many of the problems created by sometimes outdated police techniques.

Scientists have observed that sequential lineups help witnesses better identify suspects. Harris said that simultaneous lineups are not accurate because of a theory called relative judgment in which witnesses consider lineup subjects comparatively rather than individually.

“The witness wants to pick the person in the lineup who looks most like the person they remember committing the crime,” he said. “In sequential lineups that level of error is just gone.”

Harris also talked about introducing blind lineups in which the person conducting the lineup doesn’t know which subject is the suspect. This negates any unconscious signals the supervisor could give to the witness, indicating which person is the suspect.

Harris also pointed to flaws in forensics labs. Evidence left by bite marks and fingerprints might not be as accurate as people once assumed.

“This stuff isn’t science,” he said. “It is based on human interpretation and judgment, and that can be wrong.”

Harris said that many forensics labs across the country do not protect against human cognitive bias.

“You wouldn’t take over-the-counter cold medicine that didn’t go through blind testing, and yet we do this in our crime labs,” he said.

Williams responded that the scientific method will be hard to adapt to forensic labs.

“In forensic laboratories, we get a piece of evidence, and we try to work backwards and associate that with an individual,” Williams said. “The standard mathematical tools don’t work for that. We have to develop new tools.”

Fitzsimmons said that these limitations in law will be pushed with new technology.

“It is a matter of funding though,” Fitzsimmons said. “I think that just as important as improving procedures with respect to eyewitness identification and so forth is improving funding for crime labs.”

To avoid false confessions, Harris proposed taping all interrogations and barring lies about forensic evidence.

The media and entertainment industry have led people to believe that science and law enforcement work side by side, Harris said, referring to the television show CSI and several headlines he had recently found on the internet. However, Harris said that in his experience this partnership does not extend past DNA evidence.

Police have a strong view of themselves as the good guys, Harris said, and this view can sometimes be hard to reconcile with the possibility of error in their tactics.

“Those two things are in tension,” Harris said. “Human beings try and rationalize it away.”

Group polarization as well as monetary incentives placed on arrests can also deter officers and prosecutors from changing techniques, he said.

Harris concluded by noting that any modification to police culture will have to come from within the law enforcement community.

“Police and prosecutors must lead the effort,” he said. “I continue to believe that we as Americans owe it to ourselves and to our fellow citizens to do just the best that we can.”

This article has been edited to reflect a misquote in the first paragraph. The Pitt News regrets the error.