

America's 250th DNA exoneration: How often is wrong person sent to prison? - cwan
http://reason.com/archives/2010/02/08/how-many-more-are-innocent

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barrkel
> _Most prosecutors fight requests for post-conviction DNA testing._

Knowing human nature, this is understandable - there's a tendency to think
that once a "fight" has been won, it should stay won. But it's also
disturbing: does this tendency cause people to actively want to imprison
innocent people?

I've read of similar cases, where prisoners due to be executed have last-
minute appeals due to new evidence / etc., but state governors press ahead
with the execution so that they can politically appear to be "tough on crime".
The problem being that the appearance of being tough on crime seems to come
from killing someone, rather than actually ensuring justice is done.

~~~
sliverstorm
> Knowing human nature, this is understandable - there's a tendency to think
> that once a "fight" has been won, it should stay won. But it's also
> disturbing: does this tendency cause people to actively want to imprison
> innocent people?

It's not that they want to imprison innocents; it's a prosecutor's job to get
the defendant convicted no matter what, whether or not they personally believe
the defendant is guilty. They are simply acting as their job calls for (the
conflicting prosecution and defense attorneys in theory bringing about the
truth), because until now you could never be 100% sure. '100% sure' and 'our
legal system' do not go well together.

P.S. Don't invoke the argument over the ethically wrong claiming 'oh I was
just doing my job'- this is different; we WANT the prosecutor to behave like
that, even if he feels or even knows the defendant is innocent. It's what (in
theory anyway) makes the system work.

~~~
lmkg
I agree that an adversarial system is an effective system for truth discovery.
However, in order for it to be an effective and unbiased truth discovery
system, there need to be a couple of restraints on both parties, like fully
sharing information and evidence. Because prosecutors are incentivized to
achieve prosecutions rather than truth, they are encouraged to push (or break)
those constraints. While the adversarial system is reasonably effective in
theory, the fact that one side is encouraged to miss the forest (truth) for
the trees (conviction) has degenerate effects on edge cases.

The other major problem is advocacy gap. An ambitious prosecutor looking to
jump-start his career will provide unbalanced advocacy compared to a pro-bono
defense lawyer.

~~~
nollidge
> the fact that one side is encouraged to miss the forest (truth) for the
> trees (conviction) has degenerate effects on edge cases

You have to take into account the fact that the defense is encouraged to miss
the forest (truth) for the trees (exoneration) as well.

~~~
lmkg
True. However, rather than balancing out, in practice that doubles the number
of edge cases.

------
indiejade
_According to a new report by the Innocence Project, those 250 prisoners
served 3,160 years between them; 17 spent time on death row. Remarkably, 67
percent of them were convicted after 2000—a decade after the onset of modern
DNA testing._

My guess: more often than not, it's simply an issue of legal politics.
Investigators or prosecutors have pressure put on them to lock up _somebody_ .
. . _anybody_ as a means to close a case or re-direct media attention. Getting
the actual culprit almost seems to be of secondary importance. Loose
killers/rapists demand much more media attention than those who've been put
behind bars, and having such people on the loose means that people might
portray their local law enforcement officials as "not doing their jobs".

@asolove: Well, there's that Florida man who was exonerated after 35 years in
prison, thanks to DNA evidence:

[http://crimesandjustice.com/james-bain-freed-35yrs-prison-
in...](http://crimesandjustice.com/james-bain-freed-35yrs-prison-innocent-man)

~~~
khafra
Also, by all accounts I've read, forensic science isn't exactly held to
scientific standards--they use so many tests that have never been
experimentally evaluated, it could more accurately be called forensic
folklore. Since judges and lawyers are seldom clueful about the natural
sciences, often very strong evidence is ignored in favor of the word of an
"expert."

~~~
eru
Or witnesses.

------
ellyagg
> The certainty of DNA testing means we can be positive the 250 cases listed
> in the Innocence Project report didn't commit the crimes for which they were
> convicted

This is simply not true. Matching DNA against the defendant is basically 100%,
but that doesn't take into account the circumstances of the case and where
that DNA fits into the evidentiary chain. All the DNA has to do is provide
reasonable doubt. It does not prove innocence. Indeed, contrary to the claim,
it is virtually certain that some of the convicted in the overturned cases
_did_ commit their crimes.

Because of the political will behind resurrected DNA cases, the circumstantial
link doesn't need to be very strong to have a case overturned via DNA.

~~~
barrkel
And of course, there is always Bayes to take into account. If a jury hears
that there's only a "one in a million" chance that a DNA match would happen
randomly, they may overweigh this fact, when put up against e.g. a city of 3
million people - which, assuming no other evidence and that the criminal is
known to be from the city, would make the chance of this guy being the guilty
party only 1 in 3.

~~~
Estragon
That reasoning would only hold if you surveyed the DNA of everyone in that
city, which is never the case.

~~~
barrkel
No, you don't need to survey everyone in the city. Assume you instituted a DNA
search, whereby you went from district to district and tested DNA until you
got a match, the chance would still be only 1 in three, under the same
assumptions.

And government policy here in the UK seems to be to retain the DNA of everyone
that comes into contact with the state, so I expect it's only a matter of time
until there will be chance collisions resulting in incorrect convictions.

~~~
Estragon
OK, it only applies if you survey everyone in the city until you get a match.
Same difference. Yes, things may be heading in that direction. That was not
the original argument, though.

------
rauljara
This article details not only the wrongful conviction, but wrongful execution
of a Texan man accused of arson. It's a little long, but worth the read, as it
really puts a human face on what a wrongful conviction can mean for someone.
[http://www.newyorker.com/reporting/2009/09/07/090907fa_fact_...](http://www.newyorker.com/reporting/2009/09/07/090907fa_fact_grann?currentPage=all)

------
otakucode
The one fact you will never hear when DNA results are being discussed: 1 out
of every 100 DNA tests are bungled by the testing lab. Either through mistake,
contamination of samples, whatever. So that "1 in X billion" odds they toss
around should be viewed with that fact in mind. Oh, and you're not allowed to
mention it in court. Ever. They're too afraid the jury will get confused.

(The book "Drunkard's Walk: How Randomness Rules Our Lives" contains all the
details.)

------
asolove
I always wonder about this and chimera. Anyone know of cases where the right
person was set free? <http://www.thetech.org/genetics/ask.php?id=23>

------
natrius
In Texas' next execution, the state is refusing to allow the remaining
evidence to be DNA tested. You'd think we'd want to be as certain as possible
that innocent people aren't getting executed...

[http://www.texastribune.org/stories/2010/jan/28/dead-man-
bal...](http://www.texastribune.org/stories/2010/jan/28/dead-man-balking/)

~~~
bediger
I believe you should be careful about pronouns. The "we" in "we'd want" must
mean "the people of Texas", and when considered like that, isn't true. Polls
show Texans overwhelmingly in favor of the death penalty, even when we (as in
all of the US citizens) know that panalty is applied very unequally along
racial and economic class lines.

~~~
natrius
Texans favor the death penalty, but I sincerely doubt that they favor
executing innocent people. They may not want this guy to get any more chances
to prove his innocence, but that would be due to broken logic, not the desire
to execute innocents.

------
nfnaaron
Convicted in 1976. My entire adult life, buried under a prison wall. So many
kinds of people I've been, lives I've lead, so many people I've known, things
I've done.

