We all know justice is supposed to be blind, so that she won't be swayed by superficial details. She's above all that, weighing the charges against the evidence and coming out with only the truth. Well, that's how it's ideally supposed to work. But the problem with the machinery of justice is that it gets all gummed up by us humans. Even the most seemingly rock-solid legal evidence can wind up more full of shenanigans than an Irish frat house. For example ...
#5. Fingerprints Are Scientifically Unreliable
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Come on. Fingerprints are solid evidence. They have to be. They're fingerprints. Surely every single TV show in history didn't lie to us. Every single person's fingerprints are different, so they're a foolproof way to identify who's touched something. We've been using them in criminal cases since the 19th century, for Pete's sake!
How It Can Go Horribly Wrong:
Your fingerprints might not be all that unique -- and even if they were, there are a large number of variables that can make technically different prints seem very similar. See, getting the perfect fingerprint from a crime scene is something of a white whale. As often as not, investigators are lifting partial prints, which is how things can go haywire. Maybe fingerprints of you and Strong Dong Johnson, the Philadelphia Penis Strangler, share a bit of a coincidental similarity. A spot of bad luck later, and you're on trial for crimes of the dick. Or what if your family member commits a crime? Yes, families share certain elements of their fingerprint patterns. Your brother's the peeping tom, but you're the one getting hurled in the back of a police cruiser.
"This is bullshit! I only creep on Instagram. He's the analog one."
Although there are standards for determining fingerprint patterns, the actual matching of them is entirely on the shoulders of the expert handling the case. As such, fingerprint identification is an extremely delicate art. And by "delicate," we mean "wildly subjective." Experiments have found that even highly respected experts can be biased, to the point where they can change their minds about the same exact set of fingerprints based on what they know about a case.
"He lost both hands while saving blind puppies from terrorists in Iraq."
"That's what they all say."
Still, old habits die hard. We've always been told that fingerprints are indisputable, and so that's what we believe. At least, right up until your brand-new fingerprint-scanning door slides open in the middle of the night and you find out that Strong Dong Johnson doesn't appreciate you taking credit for his work.
#4. Cell Phone Records Are Basically Useless
In the real world, tracking folks via their phones is less about triangulating signals before a killer hangs up and more about digging up cell phone records during the investigation phase. Cell phone towers can track the location of your phone to within a two-mile radius. That might not be accurate enough for them to pinpoint the Parkour Bandit and embark on an awesome rooftop chase, but it's more than enough to potentially ruin an alibi.
How It Can Go Horribly Wrong:
Cell phone tracking is widely used as evidence. In 2013 alone, U.S. courts saw a staggering 37,839 subpoenas, warrants, and court orders based on it. Which is kind of unfortunate, since cell phone tracking is inaccurate. So very, very inaccurate.
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"We got the perp. He's crossing into Egypt."
"Didn't this guy jack a car in Queens?"
Anyone who's dealt with a telecommunications company knows that cell phones are a huge clusterfuck at the best of times. Tracking via cell phone records is no exception. Your phone's not always going to choose the closest tower to have the best possible signal. The towers don't always have the same range, and there's plenty of overlap.
For an example of how this can go wrong, look at the case of Lisa Roberts, an ex-lover of a prostitute who was strangled in Portland, Oregon. Her cell phone data had "pinpointed" her in the area before the crime. She was forced to take a plea bargain of 15 years rather than a full 25 years in prison, and was only exonerated after serving 12 years.
"So, 'whoops' on that one ... How about we get you an iPhone and call it even?"
And yet the FBI continues to use cell phone tracking data as evidence. As of 2014, they had 32 full-time cell phone record investigators, and have trained 5,000 people to use the technology. They say two wrongs don't make a right, but surely 5,000 wrongs could make a right or two ...
#3. Hair Analysis Is Largely Subjective
Hair samples found at a crime scene are like winning the lottery for forensics experts, as they're very good at using them to find a culprit. The process is simple: Compare your hair sample with one plucked from a suspect, and voila! Another sunglasses-wielding victory for CSI!
How It Can Go Horribly Wrong:
In 2009, Donald Gates was released from an Arizona prison, where he had served 28 years for rape and murder. He was completely innocent, and exonerated by freshly-found DNA evidence. Guess how he got convicted in the first place?
There's a reason he sports the shaved look now.
Although hair analysis was a massively popular investigative tool in the 1980s and 1990s, there's a teensy, tiny little problem with it: "Matching" two hair samples is largely subjective. That's why Donald Gates isn't a unique case. A 2012 study looked into 268 cases in which the conviction hinged on hair samples, and found that a ridiculous 95 percent of the matches were deeply flawed.
"Well, we still caught, like, seven guilty guys, so I think that's a success."
According to the FBI, hair analysis isn't much better than judging somebody on their hairstyle. In 2015, they up and admitted that a "vast majority" of analysts in their elite forensic investigation squad have overstated their findings to help prosecutors get convictions. In hundreds of cases spanning 46 states. With dozens of the convicted ending up on death row.
Based on their hair.