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John Oliver calls out faulty forensic science in murder trials

"Last Week Tonight" host explains how forensic science used in criminal cases to evaluate evidence like bite marks, hair samples and even fingerprints isn't as reliable as we think.

After binge-watching TV shows like "C.S.I." and "Bones," it's easy to fancy ourselves amateur sleuths who can understand the significance of bullet ballistics, hair analysis, bite marks, footprint matches and other evidence that can get a "match" to a murderer.

However, fictional crime shows and real life rarely have much in common when it comes to forensic science. But that doesn't stop jurors from being disappointed by the lack of impressive forensic evidence like they've seen on their favorite crime dramas, which results in the aptly nicknamed condition -- "The C.S.I. Effect."

On Sunday's episode of "Last Week Tonight with John Oliver," we got a firsthand lesson in the real-life forensic science used to convict criminals, which turns out might not be as accurate as we believed. 

In the video, Oliver points out a report in Feb. 2009 by the National Academy of Sciences, which found that many forensic sciences "do not meet the fundamental requirements of science." 

Another report in Sept. 2016 from a Presidential Science Council said that "expert witnesses have often overstated the value of their evidence, going far beyond what the relevant science can justify."

Granted, not all forensic science is bad, but its reliability can be dangerously overstated, especially where expert witnesses often use the persuasive phrase "to a reasonable degree of scientific certainty" when talking about their findings in court. The funny thing is, that phrase has "no generally accepted meaning in science," according to that Sept. 2016 Presidential report.

Inaccuracies in forensic science -- including bite marks, hair analysis and even in some cases fingerprints -- used in trials got wrongful convictions, some of which have been reversed thanks to DNA testing.

Santae Tribble served 26 years in prison for a crime he didn't commit based on FBI expert testimony that claimed forensic evidence proved Tribble's hair was found at the scene of a murder. Yet when all the hairs were DNA tested, it was discovered that none belonged to Tribble, but in fact belonged to two other people and a dog. 

Microscopic hair comparison isn't the only element of forensic science under recent scrutiny. Blood splatter patterns, footwear, firearm and bite mark analysis also has weak scientific support with the results often overstated in criminal court cases, according to last year's Presidential report.

Even forensic scientists like Dr. Michael West -- who created a career out of being the go-to expert in bite mark identification for murder cases -- no longer believes in bite mark analysis and doesn't think it should be used in court, according to a 2012 deposition mentioned in the "Last Week" segment.

Oliver also points out that even when certain forensic science has been proven in reports as unreliable, judges and lawyers still use that same flawed science in trials because it has been considered admissible in previous court cases, setting precedent.

If judges and lawyers making decisions about what should be considered acceptable science isn't bad enough, Oliver also suggests that some forensic scientists who work closely with law enforcement could think of themselves as helping to "catch the bad guys" instead of remaining neutral in their findings. 

The takeaway from Oliver's segment is that perhaps shows like "C.S.I" should do more to educate potential jurors about the inaccuracies in forensic science so they understand that a bite mark in a sandwich won't lead to finding a murderer. 

At the end, Oliver suggests an idea for a much more realistic forensic TV show "CSI: Crime Scene Idiot" starring Josh Charles, Shannon Woodward, Josh Lucas, Bobby Burke, and Samira Wiley.

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