Flawed assumptions that underlie the criminal justice system produce a disturbing proportion of wrongful arrests and convictions, Professor Adam Benforado said during a June 22 interview with WHYY’s Radio Times host Marty Moss-Coane.

Unseen biases and psychological forces affect victims, suspects, witnesses, police, prosecutors, judges and jurors alike, influencing the outcome of criminal trials, said Benforado, the author of “Unfair: The New Science of Criminal Injustice.”

The book explores an array of research findings in psychology and mind sciences that have cast doubt on the reliability of eyewitnesses, demonstrated an attractive witness’ undue influence on jurors and even called into question the capacity of body cameras to objectively capture police interactions.

“We need evidence-based law,” Benforado said.  “We have evidence-based medicine. We have evidence-based business practices.  Sports teams collect data and look at hidden patterns.  Somehow the legal system has been very reluctant to do that.”

Studies have determined that one third of the time, victims identify individuals from police line-ups who have been brought in as fillers, Benforado said; "that's a very high error rate."

Many study findings challenge the assumptions that underlie police procedures, Benforado added, noting that investigators observing a suspect’s jittery limbs or averted gaze will assume, incorrectly, that they’ve confronted a liar.

“Those are bad ways to tell if someone’s telling the truth,” Benforado said, adding that police use “good cop-bad cop” strategies that can put suspects in extreme states of distress and lead them to make false confessions.

Once a confession is obtained, Benforado explained, no other suspects are considered, and lab technicians tend to make findings that support that narrative.

Even when police and jurors have the best intentions, Benforado said, they may be unaware of biases that guide their thinking and produce unjust outcomes.

The book suggests that long-term reforms like virtual trials would diminish bias and also outlines less controversial changes that could be easily implemented, such as requiring blind-testing of lab results.

Benforado will discuss the book at the Free Library of Philadelphia at 7:30 pm on June 30.