Adding a Dash of Uncertainty

Many people, myself included, grew up on television police dramas in the late 1950s andShadow of hunchback walking up stairs 1960s (and 1970s, 1980s, 1990s, 2000s and so on — when have they not been popular?).

Unfortunately, those shows lied to us. No, police don’t always nab the right guy. No, they don’t always do a thorough investigation. No, they don’t place finding the truth ahead of closing the case file. Not always.  Maybe not often.

Now it comes out that one of the fundamental piece of evidence used in those crime investigations doesn’t work.


We were told they are unique to an individual.  They aren’t. A grad school pal whose a security expert told me years ago that prints could  be faked, but the real problem is much worse.

According to an American Academy for the Advancement of Science working group,

“. . . courtroom testimony and reports stating or even implying that fingerprints collected from a crime scene belong to a single person are indefensible and lack scientific foundation.”

Comparing a partial fingerprint from a crime scene to a database isn’t definitive.

“Our review of the scientific literature found that there is no scientific way to estimate the number of people in some community — a city, a state, the country, the world — who share the characteristics found, and hence no scientific basis for identification.”

In simple English, you can’t say with certainty that a fingerprint belongs to anyone.

What we were told could be done, couldn’t. The TV shows were wrong. Quite likely, some innocent people were convicted in real courts based on unreliable evidence.

In the end, the shows don’t matter. How do we undo the damage to the real people?


  1. Carnegie Mellon University. “Fingerprints lack scientific basis for legal certainty: More research into validity of fingerprint comparisons needed.” ScienceDaily. ScienceDaily, 5 October 2017. <>



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