RENEE MONTAGNE, HOST:
Now to crime and punishment in this country and the trouble with eyewitness testimony. People who saw events with their own eyes are compelling but can also be wrong. So courts in New Jersey have tried something new. They have been educating juries on how to judge eyewitness testimony. As NPR's Nell Greenfieldboyce reports, the effort may be having unintended consequences.
NELL GREENFIELDBOYCE, BYLINE: Back in 2012, New Jersey's state Supreme Court did something groundbreaking in an effort to minimize the risk of wrongful convictions. It said when a case involves an eyewitness, judges must give jurors a special set of instructions, basically a tutorial on what scientific research has learned about eyewitness testimony and what makes it more or less reliable.
DAVID YOKUM: And the hope with this was that jurors would then be able to - sort of be able to tell what eyewitness testimony was trustworthy, what sort wasn't, and at the end of the day, it would lead to better decisions, better court outcomes, better justice.
GREENFIELDBOYCE: That's David Yokum. He was doing research into decision-making at the University of Arizona and decided to test the effect of these new jury instructions using videos of mock trials that he showed to volunteers.
(SOUNDBITE OF VIDEO)
UNIDENTIFIED MAN #1: Please be seated. Court is now in session.
GREENFIELDBOYCE: He and his colleagues made up a fictional trial, a robbery and murder at a convenient store. Actors played all the roles, including an eyewitness.
(SOUNDBITE OF VIDEO)
UNIDENTIFIED MAN #2: Mrs. Dun, is the person you saw rob the quick-stop convenience store in the room at this time?
MRS. DUN: Yes, he is.
UNIDENTIFIED MAN #2: Can you please point to this person?
DUN: Yes, that's him over there.
GREENFIELDBOYCE: They made two versions of this video. One had eyewitness testimony that would be considered strong, according to the New Jersey instructions. The other had eyewitness testimony that was weak.
YOKUM: Kind of imagine a best and a worst-case scenario, we deliberately designed the video that way.
GREENFIELDBOYCE: Here's one example. Police frequently ask eyewitnesses to identify a suspect using a photo lineup. The New Jersey instructions say it's best if the photos are shown to the witness by a police officer who doesn't know which one is the suspect.
YOKUM: And the concern there is that if an officer knows who is in the photo lineup, they might accidentally give some sort of hint to the person about who it is.
GREENFIELDBOYCE: So in their video with the strong eyewitness testimony, the officer didn't know who was who. But in the video with the weaker testimony, he did. After watching one of these videos, the juror either did or did not hear the long New Jersey instructions. And then the juror had to decide, guilty?
YOKUM: We found that the instruction had an effect, so people that were read from the judge in the New Jersey instruction were much less likely to convict the defendant.
GREENFIELDBOYCE: Yokum says that was true regardless of whether the eyewitness testimony was high quality or low quality. It's as if the instructions made the the jurors suspicious of all eyewitness testimony.
YOKUM: Whether this is, like, a good or a bad thing relative to not having the New Jersey instruction, I think it's kind of an open question.
GREENFIELDBOYCE: Alan Zegas thinks it's a good thing. He's a criminal defense attorney who handled one of the cases that led to the New Jersey instructions.
ALAN ZEGAS: Our criminal justice system, our Constitution has at its foundation the notion that it is better to let a thousand guilty people go free than to convict an innocent person.
GREENFIELDBOYCE: He says look at all the people who've been identified by eyewitnesses and later exonerated through DNA testing.
ZEGAS: There should be skepticism of eyewitness testimony.
GREENFIELDBOYCE: He says it's impossible to know what the real-world effect of these instructions has been so far. After all, most cases involve various kinds of evidence. But for those rare cases that really hinge on eyewitness testimony, the New Jersey instructions could make a huge difference. Nell Greenfieldboyce, NPR News.