Sure, we've come a long way since the days of hanging warty women for consorting with the devil, but that doesn't mean our justice system has made it all the way out of the dark ages.
Lots of what you see police doing on Law & Order is based on techniques that are proven to not work so well. But change is hard, so the system stays the same, even though ...
#5. Interrogations Can Get Innocent People to Confess
Remember what it was like to accuse a sibling of stealing a favorite possession? No matter how hard they protested or how strongly they insisted that maybe you should take a peek at that shithole you were calling a bedroom, it didn't matter. Your Jem and the Holograms cassette was stolen, and you knew who took it.
Suspect interrogation is kind of like that. If the interrogator is convinced the suspect is guilty before the interrogation starts, it's hard to change his mind. He or she will assume everything from cries of innocence to constant crotch-scratching is proof of guilt, which leads to a more aggressive line of questioning. But who cares? If the bad guy confesses, the good guys win -- it's the one time you know for sure you got the right guy. That's why just about any confession makes a jury more likely to convict, even if the jury is told that the confession was coerced. After all, no matter what, an innocent person isn't going to confess to something he didn't do.
"That's right, little Jen. Just confess to selling all that coke and we'll buy you some cotton candy."
So What's the Problem?
Wrong. It happens all the time. And we mean all the time. In one famous 1989 case of a rape of a jogger in Central Park, five men went to jail after the cops got them to confess to the assault. Then they were released, after it turned out they didn't do it (another guy already serving time for a different assault finally came forward).
"Only the guilty have anything to fear. And the innocent, if we're having a slow day."
It turns out it's actually not all that hard to get a confession out of an innocent person. The same high-pressure psychological techniques meant to wear down a guilty suspect will make a lot of innocent people confess to something they didn't do. Since innocent people are more likely than criminals to waive their right to remain silent, they're put in a high-stress situation where they're not even clear about what they're being charged with. They also may feel guilt for some unrelated reason (they saw the crime and failed to report or stop it, for example). So, they say whatever they need to say to make the interrogation end.
For instance, one popular interrogation technique has the interrogator give a monologue claiming he already knows the subject is guilty, and then follows nine scripted steps to get a signed confession. It's incredibly effective -- it gets guilty suspects to confess nearly 84 percent of the time. Oh, and it gets innocent people to confess approximately 43 percent of the time. Add hinting at fake evidence, and you can up that false confession rate to about 94 percent.
"You ever wonder if maybe all these head games and lies get in the way of, y'know, justice?"
It's hard to argue with success! Especially if you're behind bars.
#4. Composite Sketches Are Pretty Much Useless
You've seen this in every cop show ever: The victim describes the man who assaulted her, the police have a guy there with a sketch pad drawing up what she describes. Then they can put that "composite sketch" out on the street and find their man. In other words, the composite sketch is created with the hope that a picture like this:
Will get you a person like this:
Via Wikimedia Commons
It's like seeing double!
So What's the Problem?
In reality, victims who assist in creating a composite sketch of their assailants are nearly 50 percent less likely to correctly identify a suspect later.
The first problem is that, as you might have already noticed, sketch artists are usually terrible at their jobs. In one demonstration, an artist was asked to recreate the faces of famous people while looking at their pictures. This was the breathtakingly miserable result:
Via Face Processing
This isn't a joke, from left to right: Bill Cosby, Tom Cruise, Ronald Reagan and Michael Jordan.
These days, instead of old-fashioned pencil and notepad, we have special software to do the job for us. The terrible, terrible job. While human sketch artists are bad, software is even less effective. In one study, hand-drawn sketches led to a 32.8 percent correct identification rate, while computer-assisted sketches ended up correct only 22.4 percent of the time. That kind of success rate is a bummer if you're trying to identify the anonymous stranger who fed your parking meter, but it's a tragedy if you're trying to identify the guy who viciously murdered your best friend and might be coming for you next.
The other problem is that the act of creating a composite sketch confuses the hell out of the victim. Your memory is actually very suggestible, thanks to a phenomenon called source amnesia, which basically means the brain remembers facts, but doesn't remember where we learned them. That means if the artist gets something wrong in the sketch (the suspect's nose is too big, or he has too many eyes), the victim literally starts to think that's what the suspect looks like. The brain doesn't remember if you first saw that feature in the real face or on the sketch. So the cops drag in a guy who looks like the inaccurate sketch and you say, "That's him!"
What we're trying to say is, if you want to stay out of jail, don't have a face that looks like a terrible drawing.
#3. Lineups Are Pretty Useless, Too
Let's say, God forbid, something terrible happens to you, like that you're flashed in the park or somebody drunkenly poops in your swimming pool. Fortunately, you got a quick look at the guy before he ran away. Now the only thing between you and sweet justice is picking the perp out of a police lineup.
Shouldn't be too hard.
So What's the Problem?
By viewing a bunch of people together, most eyewitnesses use relative judgment to choose a target, which means the brain doesn't quite go for an exact match. After all, you don't want the guy to go free, or to think you've wasted everyone's time doing the lineup. So instead of picking out the guy who is an exact match for your memory (which, as we established, is a little hazy anyway), you're going to pick whichever guy is the closest match of the guys in front of you. Which is kind of a problem if your pool shitter isn't actually in the lineup.
And sometimes the policemen facilitating the lineup aren't helping. Remember, they know which of the people up there were just brought into fill out the lineup (such as off-duty cops) and which one is the chronic pool shitter they're pretty sure did it. So there's one guy up there the cops want you to point out, and humans have a million ways to subtly influence the decisions of other people, whether they mean to do it or not.
"It's #4. Say #4."
For instance, voice inflections, stressing the witness and even unconscious hand gestures can steer the witness toward the cop's preference. Once the "correct" selection is made, the police may lavish praise on you, which artificially boosts your confidence at trial. That's a big deal -- most juries base their judgments largely on witness confidence. So that whole skewed process of first getting you to finger the wrong guy and making you more and more sure about your decision can put an innocent man behind bars.
To give you an idea of how shaky that whole process is, merely reminding the witness that the suspect may not be in the lineup decreases misidentification by about 46 percent (even though that should go without saying -- if they knew for sure, there'd be no reason for the lineup in the first place). You can also increase accuracy just by having the lineup conducted by somebody unfamiliar with the case, so they're not subconsciously steering the witness one way or the other.
"Guest officer ... Carrot Top!" "Murder? I barely knew 'er!"
We're not trying to paint the police as a bunch of corrupt stooges eager to throw anybody and everybody into prison. They're under enormous pressure to close cases and get bad guys off the street. There's no reason to stop using a technique that helps get convictions, and in fact, all of the pressure is going the other way. And that goes a long way to explaining the last two ...