Monday, May 23, 2016

The Eye of the Beholder

“The time has come," the Walrus said,
     “To talk of many things:
Of shoes--and ships--and sealing-wax--
     Of cabbages--and kings--
And why the sea is boiling hot--
     And whether pigs have wings.”
Lewis Carroll, "The Walrus and the Carpenter"
If you'd been paying attention, you knew it sooner. If you hadn't been paying attention, you should have known it in 2009 when the National Academy of Sciences released its report, Strengthening Forensic Science in the United States: A Path Forward.
Nearly all of what passes for forensic science is bullshit.
  • Fingerprints? Bullshit.
  • Shoe prints and tire tracks? Bullshit.
  • Ballistics? Bullshit.
  • Bullet lead analysis? Bullshit.
  • Bitemark comparison? Extreme bullshit.
  • Hair comparison analysis? Total, utter, beyond the pale bullshit.*
Ah, but there was still DNA.  That, the NAS report acknowledged, was actual science.  Which is, in fact true.  It is science.  Developed by scientists.  

Take a sample of something with human cells, even extraordinarily tiny amounts these days, run it through the pocketa pocketa high tech machine and you get results.  Then you compare the results to whatever and either it's consistent or it isn't.  

Which is clear and simple enough.  And even accurate.  

If everything is perfect.  Proper samples, properly protected against contamination and accurately tagged with the right person's identity.  Competent technicians performing their jobs in exactly the way they're supposed to.  Accurately calibrated equipment in perfect working order using solutions that themselves aren't contaminated. 

And oh, yeah, a single sample rather than a mixed one.

Then, you'll get results that . . . .

Well, see, there's a problem.  And the more you have to do, whether it's clone the initial sample gazillion times because it's so small or deal with the fact that it's degraded or have that mixture where there are two or more contributors.

Matthew Shaer in the Atlantic. 
A groundbreaking study by Itiel Dror, a cognitive neuroscientist at University College London, and Greg Hampikian, a biology and criminal-justice professor at Boise State University, illustrates exactly how subjective the reading of complex mixtures can be. In 2010, Dror and Hampikian obtained paperwork from a 2002 Georgia rape trial that hinged on DNA typing: The main evidence implicating the defendant was the accusation of a co-defendant who was testifying in exchange for a reduced sentence. Two forensic scientists had concluded that the defendant could not be excluded as a contributor to the mixture of sperm from inside the victim, meaning his DNA was a possible match; the defendant was found guilty.
Dror and Hampikian gave the DNA evidence to 17 lab technicians for examination, withholding context about the case to ensure unbiased results. All of the techs were experienced, with an average of nine years in the field. Dror and Hampikian asked them to determine whether the mixture included DNA from the defendant.
In 2011, the results of the experiment were made public: Only one of the 17 lab technicians concurred that the defendant could not be excluded as a contributor. Twelve told Dror and Hampikian that the DNA was exclusionary, and four said that it was inconclusive. In other words, had any one of those 16 scientists been responsible for the original DNA analysis, the rape trial could have played out in a radically different way. Toward the end of the study, Dror and Hampikian quote the early DNA-testing pioneer Peter Gill, who once noted, “If you show 10 colleagues a mixture, you will probably end up with 10 different answers” as to the identity of the contributor. (The study findings are now at the center of the defendant’s motion for a new trial.)
Because the real world problems aren't the ones you solve in a classroom.  And the problem with DNA isn't the science.  It's what happens after the science.  What happens when someone has to interpret the results.  And maybe put an innocent person away for life.

Does it happen?  Yeah.  How often?  Nobody knows.  And just about nobody believes it.

 "The sun was shining on the sea,       Shining with all his might:
He did his very best to make
      The billows smooth and bright —
And this was odd, because it was
      The middle of the night. 

The moon was shining sulkily,
      Because she thought the sun
Had got no business to be there
      After the day was done —
"It's very rude of him," she said,
      "To come and spoil the fun." 

The sea was wet as wet could be,
      The sands were dry as dry.
You could not see a cloud, because
      No cloud was in the sky:
No birds were flying overhead —
      There were no birds to fly. 

The Walrus and the Carpenter
      Were walking close at hand;
They wept like anything to see
      Such quantities of sand:
If this were only cleared away,'
      They said, it would be grand!' 

If seven maids with seven mops
      Swept it for half a year,
Do you suppose,' the Walrus said,
      That they could get it clear?'
I doubt it,' said the Carpenter,
      And shed a bitter tear. 

O Oysters, come and walk with us!'
      The Walrus did beseech.
A pleasant walk, a pleasant talk,
      Along the briny beach:
We cannot do with more than four,
      To give a hand to each.' 

The eldest Oyster looked at him,
      But never a word he said:
The eldest Oyster winked his eye,
      And shook his heavy head —
Meaning to say he did not choose
      To leave the oyster-bed. 

But four young Oysters hurried up,
      All eager for the treat:
Their coats were brushed, their faces washed,
      Their shoes were clean and neat —
And this was odd, because, you know,
      They hadn't any feet. 

Four other Oysters followed them,
      And yet another four;
And thick and fast they came at last,
      And more, and more, and more —
All hopping through the frothy waves,
      And scrambling to the shore. 

The Walrus and the Carpenter
      Walked on a mile or so,
And then they rested on a rock
      Conveniently low:
And all the little Oysters stood
      And waited in a row. 

The time has come,' the Walrus said,
      To talk of many things:
Of shoes — and ships — and sealing-wax —
      Of cabbages — and kings —
And why the sea is boiling hot —
      And whether pigs have wings.' 

But wait a bit,' the Oysters cried,
      Before we have our chat;
For some of us are out of breath,
      And all of us are fat!'
No hurry!' said the Carpenter.
      They thanked him much for that. 

A loaf of bread,' the Walrus said,
      Is what we chiefly need:
Pepper and vinegar besides
      Are very good indeed —
Now if you're ready, Oysters dear,
      We can begin to feed.' 

But not on us!' the Oysters cried,
      Turning a little blue.
After such kindness, that would be
      A dismal thing to do!'
The night is fine,' the Walrus said.
      Do you admire the view? 

It was so kind of you to come!
      And you are very nice!'
The Carpenter said nothing but
      Cut us another slice:
I wish you were not quite so deaf —
      I've had to ask you twice!' 

It seems a shame,' the Walrus said,
      To play them such a trick,
After we've brought them out so far,
      And made them trot so quick!'
The Carpenter said nothing but
      The butter's spread too thick!' 

I weep for you,' the Walrus said:
      I deeply sympathize.'
With sobs and tears he sorted out
      Those of the largest size,
Holding his pocket-handkerchief
      Before his streaming eyes. 

O Oysters,' said the Carpenter,
      You've had a pleasant run!
Shall we be trotting home again?'
      But answer came there none —
And this was scarcely odd, because
      They'd eaten every one."

*Really, the hair comparison thing is dramatic.  The FBI admitted last year that its analysts consistently reached worthless conclusions and testified to the absolute nonsense in criminal trials leading to hundred if not thousands of convictions and at least 32 death sentences - including 14 people who've been executed.  And, of course, they trained crime lab analysts across the country to do the same dangerously inaccurate work.  From the Washington Post story last year:
Peter Neufeld, co-founder of the Innocence Project, commended the FBI and department for the collaboration but said, “The FBI’s three-decade use of microscopic hair analysis to incriminate defendants was a complete disaster.”

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