The Science Doesn't Lie?

It does, if you don't understand it.

Turn on the TV most any evening, and be prepared to spend time watching a police crime lab. With the proliferation of CSI shows - New York, Miami, Las Vegas, who knows where next - American audiences have been introduced to the science of criminology.  Time after time, some apparently perfect crime is unsnarled by scientists in the lab, analyzing a stray hair, piece of fabric, partial fingerprint, or other obscure but infallible identifier.

As a result, juries in the real world are increasingly demanding fancy scientific proof in order to return a conviction - the "CSI effect."  And since they want to win cases, district attorneys are happy to comply.  So we get tremendous increases in state lab budgets, outsourcing of analysis to independent private labs, and of course, the famous FBI forensic lab.

It's interesting to consider the underlying reasons behind this phenomenon.  At one time, the ultimate proof in court would be a sworn witness giving testimony, preferably a police officer.  But having been exposed to the many weaknesses of witnesses, from Officer Mark Fuhrman's perjury in the O.J. Simpson murder trial, right on up to President Clinton lying about his extracurricular activities, juries are understandably more cynical about the truth of what witnesses have to say.

They'd like to see something a little more concrete - something scientific, impartial, and reassuring.  Combine that with the Hollywood indoctrination of CSI, and this development makes perfect sense.

The only trouble is that "someting scientific" isn't always concrete.  Forensic evidence in the real world is rarely clear-cut and significantly more nuanced than forensic evidence in the TV world.  It has become increasingly clear that mistakes are rife in police labs, with impossible DNA returns and other such disturbances.

Recently, we see that even the FBI doesn't always get it right.

For many years, the FBI has done bullet-lead analysis comparisons for prosecutions.  The idea was that each batch of molten lead that's cast into bullets is slightly distinct from the last batch - it contains trace elements that the smelting process didn't quite remove, in different proportions based on any number of influences.  So a crime scene bullet can be compared to unfired bullets in the suspect's possession, and if they match, the suspect must have owned the bullet used to commit the crime, and therefore is involved somehow.

After decades of usage, researchers discovered that the statistics in the test are faulty so the conclusion is often wrong.  The bullet lead doesn't differ enough to say anything useful.  And the batches are too large - sure, one boxcar-load of bullets may differ from another boxcar-load, but you still have ten thousand different people with chemically identical bullets, who have nothing more in common than that their bullets were shipped from the manufacturer on the same day.  How is this helpful?

The test looked scientific and sounded scientific, and it allowed juries to feel better about convictions.  But how many times was the test the incriminating factor for an innocent person?  We just don't know -- because the juries saw the science (grouped with all the other measurements and figures), and were further reassured by it.

Our jury system requires a certain amount of work and thought on the part of the jury.  There is no shortcut.  A juror must listen to, and weigh, all the evidence presented; make adjustments for how truthful he believes it to be; and make a judgment call.

Cases are to be proven "beyond all reasonable doubt," which is far different than being proven beyond any doubt whatsoever.  Scientific evidence is only as reasonable as it is accurate.

Hollywood-saturated juries, lazy prosecutors, police blunders.  Innocents convicted - and, in some ways worse, guilty men who may now be wrongfully set free to commit other crimes.  What a mess.  There won't be a happy ending with justice served, like there is on CSI.

Petrarch is a contributing editor for Scragged.  Read other articles by Petrarch or other articles on Society.
Reader Comments

There is some hope as the judges catch on.  Some months ago, a judge asked the FBI if they had even done a study of the accuracy of matching partial fingerprints.  They had not.  So nobody knows how many false positives partial prints give.

The judge asked the FBI to look into the matter before asking him to admit partial print evidence in his court room.

On the other hand, another judge expressed joy at the availability of computer-based evidence because computers were so precise and accurate.  He had no idea how easy it is to fake computer files including dates of origin.

And remember silicone breast implants?  After several billion dollars paid out to trial lawyers, with a few bucks here and there going to supposed victims, it was proven that silicone has no effect on the immune system; the FDA re-approved the implants.

Cops and prosecutors are ALWAYS under pressure to jail a culprit regardless of innocence or guilt, particularly if they can generate massive headlines which might get them elected governor.  The Duke lacrosse players accused of rape would probably have done time if they hadn't had enough money to get good lawyers and if the prosecutor's misconduct had been a bit less egregious.

Getting wrongly convicted is like stepping in front of a bus - events occur, as the bumper sticker says.

November 21, 2007 3:13 PM

It is important to note that the FBI did NOT screw up in that recent Washington Post investigation.  That case was about a local crime lab that was working for local police.  They fudged some data, ignored written notes and used an "expert" that lied about his college degrees among other things.  The FBI had already stopped using the lead test and had told police departments to stop using it too before that incident.  The only possible sin that the FBI committed was that they didn't tell 1000 criminals in jail that they needed new trials.  I happen to believe that they shoudn't have.  The Washington Post never bothers to mention if the "thousands of other innocent" people had any other evidence against.  From what we know about the lead test, it was never an incriminating factor on its own.  It may have bolstered other evidence, but it is highly unlikely that hundreds of other criminals will go free over this.

November 21, 2007 3:29 PM
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