how junk science can land you on death row

Far too much of what passes for forensic science in courtrooms fails to meet basic scientific standards while sending people to jail. And those who could fix this problem are refusing to help us.





If you watch Netflix’s The Bundy Tapes, you’ll be reminded that the 1970s and 80s were the golden age of serial killers, as over 200 of them operated all over the United States. Unlike we often picture, they weren’t exactly bloodthirsty geniuses who outwitted police at every step. In fact, the average serial killer had a below average IQ and was often caught making the sort of mistakes we’d expect to catch within hours today. Most of Bundy’s killings could be caught in just weeks with today’s technology and law enforcement methods, which is why most experts tend to cite a complete lack of intelligence sharing between police, vast highway networks, and exposure to lead as a once in a generation opportunity for murder sprees.

While one pundit predicts another wave of such killers in the next 15 years based on studies of past serial killers’ childhoods, criminologists don’t think the horror sprees of the late past century will return thanks to modern policing and technology. As you’ve seen glorified in countless TV shows named after the aftermath of a Scrabble board explosion, we have forensic science and smartphones now. We’re solving old cold cases with genetic libraries and have access to the digital trails of literally billions of people across the world, on top of decades of ever-improving techniques that allow us to tie criminals to their misdeeds, meaning that today’s serial killers are either really, really good at killing, or simply aren’t there in large numbers.

Or, at least, that’s what forensic experts who make a living testifying in court, the prosecutors who employ them, judges, and TV producers want you to think. The reality is a lot messier and actually rather disturbing. Instead of a library of earnest forensic sciences, we have a mess of techniques that range from virtually ironclad to complete junk, and a lot of the latter is allowed in court despite years of growing protests from actual scientists and experts. As a result, people are being convicted for crimes they didn’t commit by prosecutors who just want another win on their record, while real criminals go free to steal, rape, and kill again.

how prevalent is forensic junk science?

Investigative journalists have been pursuing stories of wrongful convictions and junk science in courts for years, unearthing a disturbing focus on getting convictions and protecting reputations rather than making sure that the right criminal was sent to jail or death row. For example, Texas executed Cameron Todd Willingham for setting fire to his house and killing his children, fighting experts pointing out the junk science used to convict him every step of the way to ensure his death sentence was carried out. David Lee Gavitt faced life without parole for a similar crime, based on similar junk science as Willingham. It took 26 years for him to be exonerated.

Likewise, Joe Bryan of Texas spent 30 years in prison for the murder of his wife based on the pseudoscientific discipline of blood spatter analysis, which quite literally started in one man’s basement and spread by virtue of being lent credence by judges instead of scientific authorities. In the same vein, systemic studies of FBI’s image analysis found numerous replication problems and wild, unsupportable claims being passed off as science. The same can be said for a whole lot of other forensic approaches like bite mark analysis, hair analysis, footwear and tire analysis, fire and explosion investigation, and even behavioral profiling.

Basically, if a forensic technique is taught with 40 hour classes that don’t require scientific credentials or is passed on through apprenticeships like a trade, odds are that it’s only being used in a courtroom because its advocates inflate its accuracy, prosecutors push to include it, and judges choose to allow it with no regard for scientific standards. A very sobering segment on Last Week Tonight has a great summary with some pretty chilling statistics.

In what is currently the heyday of true crime stories and programming about the follies of the justice system, we’re seeing and talking about a lot of complicated cases involving confusing testimony, questionable, if not forced, confessions, and less than noble actions from police and prosecutors. But we’re not spending nearly enough time talking about dubious experts passing home experiments as airtight science with meaningless phrases and being allowed to do so by judges lacking an objective, peer-reviewed standard to follow in what methodology to accept or reject during trials. Even worse, we’re not freaking out about the Trump administration shutting down efforts to create such a standard.

battling the csi effect

Sadly, one of the biggest hurdles to stamping out junk science in the courtroom are the juries, who now expect forensic evidence in every trial and outlandish claims of accuracy, assuming that whatever they hear from the stand is hard, settled science. This is known as the CSI Effect, after the franchise of primetime crime procedurals in which attractive crime lab employees testify that they can pinpoint a killer based on the DNA of a single hair fragment lifted off the victim’s badly deteriorated cadaver with one in a trillion accuracy. Prosecutors and the experts they recruit are happy to lean into this popular impression, and many defense lawyers lack the skills and scientific literacy to properly challenge seemingly credible experts.

This is simply not how forensic evidence works in real life due to numerous sources of genetic contamination we all encounter in our daily lives, the deterioration of evidence as time between the crime and discovery passes, and much of the evidence necessary for a proper conviction still has to be gathered by good, old fashioned police work. It’s not glamorous or exciting, and unless done right, it probably wouldn’t make for riveting TV. But there are some incredible investigations that rely on nothing more than asking questions and following up on leads. If more people were re-exposed to this classic, Sherlock Holmes style of police work, maybe it could help combat slick CSI technobabble just by virtue of novelty.

We also need our politicians to continue the work of reviewing what passes for science in criminal cases, allowing scientists to issue evidence-based guidelines to help judges and attorneys draw the line on what should be accepted in a case and what should be tossed aside. Making sure we eliminate cargo cult science from courtrooms isn’t just about maintaining high standards of scientific accuracy and peer review, it’s about making sure that innocent people go free and criminals are in jail instead of being given a free pass while someone else takes the blame for their sins, or able to muster pseudoscientific excuses to get themselves off the hook.

We certainly want prosecutors who will fight for us and put bad guys behind bars. But how much good are they doing if their focus is on getting convictions by any means necessary, even if they end up laundering the pseudoscientific nonsense of wannabe experts, letting the actual bad guys evade the police, which is now confident the perpetrator of a crime they were investigating is now behind bars? And just as we don’t want prosecutors claiming that an expert in whatever analysis to ensure a guilty verdict by confidently spewing random buzzwords that sound like science to juries, we don’t want defense attorneys concocting dubious defenses to free actual criminals trying to take advantage of a broken system.