Wired has a piece up entitled "America's Justice System Sure Doesn't Know Much Science." Amen to that. The crux of the article is that the criminal justice system is full of (you could argue it's practically built upon) premises which are not only questionable, they're flat out false. From Wired:
Americans inherited a legal system shaped by history, not by science. “The legal system is resistant to change and resistant to paying attention to scientific research,” says Adam Benforado, a law professor at Drexel University and author of the recent book Unfair: The New Science of Criminal Injustice. The system assumes that innocent people don’t confess to crimes they didn’t commit. It presumes that eyewitness testimonies are reliable. It counts on the impartiality of jurors.
None of those things are borne out by evidence.
The article does a good job explaining some of these false premises - like false confessions. For years the system (and a lot of convictions not to mention a lot of exonerations) has been built on the idea that an innocent person would not confess to something he/she didn't do. But...
Interrogations are designed to mentally break down the guilty, but those psychological tricks leave the innocent vulnerable as well, says Saul Kassin, a psychologist at Williams College who has studied false confessions. “When people are asked. ‘why did you confess?’ they say, ‘I wanted to go home.’” he says. “That’s a testament to their state of mind.”
The problem begins with pre-interrogation interviews, where police are often trained to look for behaviors—like jittering or avoiding eye contact—that supposedly reveal lying. In fact, peer-reviewed research shows those behaviors are not reliable signs of lying at all.
By the time the police haul someone in for interrogation, they’re already assuming the suspect is guilty. They can then spend hours badgering the suspect before adopting a more sympathetic pose with minimizing remarks like “We think you were provoked” or “You just had too much to drink.” Courts have ruled police are not allowed to promise leniency—precisely because it leads to false confessions. But Kassin’s research shows that in a lab setting, suspects interpret those minimizing remarks as implicit promises of leniency.
What about false memories?
In 1987, Jennifer Thompson got on a witness stand and said she was “absolutely sure” Ronald Cotton had raped her three years earlier in Burlington, North Carolina. Eight years later, DNA evidence exonerated Cotton of the crime.
Despite Thompson’s certainty in court, she barely recognized Cotton when she first had to pick him out of photos and a line-up. She would later describe how the detectives’ efforts to reassure her—“You did great” and “It’s the same person you picked from the photos”—made her confident in her decision. When she met the real perpetrator, she didn’t recognize him at all, remarking at the time, “I have never seen him in my life.”
Thompson’s faulty recollection is not surprising given what neurobiologists know about memory. Every act of recall involves a process called reconsolidation, the recreation of the memory. On a molecular level, reconsolidating a memory is much like forming a new one. In other words, memories are just reconstructions. That makes them startlingly easy to change.
Personally, I've seen this time and again in my own cases. The police officer talks to the witness, encourages the witness, affirms the witness... the prosecutor then preps the witness... if the witness stumbles the prosecutor might prompt them with their previous statements or (worse) with what fits into the prosecutor's theory. None of this need be intentionally nefarious. That's what's truly scary - evil prosecutors out to convict people they know are innocent are rare. Well-meaning prosecutors trying to do what they think is right and "catch the bad guy" are common... but the latter can stumble into many of these problems unintentionally. Doing so can profoundly alter a witness' memory and turn a case on it's ear.
What about bias? We barely scratch the surface of some biases the jurors might have in jury selection. Can't be fair to someone charged with XYZ crime? Can't give a cop a fair shake? Think anyone charged with a crime is guilty of something? Okay, a good jury selection can handle those biases to some degree (to the degree jurors speak up openly and honestly - which, let's not kid ourselves, is rare). What about something we know (from science) exists: attractiveness? We know people are biased against unattractive people. Otherwise the marketing industry would sell you stuff with overweight, ugly models.
And what about my personal pet peeve: the insanity defense?
In the 46 states that accept a version of “insanity” as a legal defense, the word has a very particular legal definition...to be shown to be unable to tell right from wrong.
That puts forensic psychiatrists and juries in the difficult position of reconstructing a defendant’s mental state during the time of the crime. “There’s no reason for us to have strong confidence in our view,” says William Carpenter, a psychiatrist who testified for the defense in the trial of John Hinckley, Jr., found not guilty by reason by insanity for attempting to assassinate President Ronald Reagan. “Reasonable people would and did disagree over whether Hinckley was legally sane,” says Carpenter.
The DSM lays out the diagnostic criteria for [recognized mental illnesses]. But the word “insane” does not appear. It’s not a medical term, but it is still a legal one.
Simply put: the article is worth a read.