Sunday, April 11, 2010

Appeals Court to Rule on Junk Science

No one disputes that certain varieties of canines can track humans in flight by following their scent in a trail that only they can “see.” It’s a Southern tradition, you might say, born of a need to follow and capture escaped slaves.

So that’s not what is in question. What is in question is (some would say) an unreasonable extension of a dog’s ability to detect human scent. That not only can a dog detect the scent of a human, but the same dog is able to discriminate between the scents of one human and another.

We have dead solid perfect methods to discriminate between one human and another. The first was the discovery that the fingerprints of individual humans were as unique as snow flakes: no two are alike, even the fingerprints of identical twins are different. But there are even standards in this area of forensic science. A minimum number of matches or points are needed to be considered a valid identification. This is the result of rigorous scientific testing and statistical analysis.

And in the 90’s we had the miracle of DNA identification that makes fingerprint matching look like junk science.

But here in Texas, we have former Fort Bend County Sheriff’s Deputy Keith Pikett, and his bloodhounds Columbo, Quincy, James Bond and Clue to thank for putting several individuals behind bars. Life sentences issued to innocents for their crime of having a scent that some dog thinks it has smelled before.

The case of Richard Winfrey, Sr. is to be reviewed this coming Wednesday by the nine justices who sit on the State Court of Criminal Appeals. At stake is the reputation of the former deputy and the olfactory organs of his dogs.

And oh, yeah, the freedom of unjustly jailed victims of a criminal justice system that relies on junk science.

As a forensic science, the ability to dogs to discern between one human’s scent and another’s has never, ever been proven. Take a look at this 10-year old article by a Polish forensic scientist.

“The problem of validity and reliability is vital for any forensic science method. Dog scent lineup reliability was examined chiefly by Schoon (1997, 1998). It was measured in diagnostic ratio, i.e. the quotient of “hits" and “false alarms". Depending on the experiment’s configuration, the raw diagnostic ratio ranged from 4.3 (Schoon, 1997) to 6.9 (Schoon, 1998), whereas the diagnostic ratios of other common forensic identification methods vary from 3 to 160 (Schoon, 1997). It should be noted that the percentage of correct dog scent identifications according to the Dutch research was not impressive: 32% and 58%”

But most telling of all is the story of the three separate trials for which Winfrey was found guilty in one of them. Winfrey’s children were both also charged in the murder of Murray Burr. Winfrey’s daughter was also found guilty, but his son was acquitted after the jury met for 13 minutes.

The difference in Winfrey’s trial, as well as that of his daughter, was that the validity of scent lineups was not questioned by their defense attorneys. His son’s lawyer, however, “introduced evidence from a forensic scientist that attacked Pikett's training, scent lineup methods and conclusions.”

So it’s time, I think, to rule on the validity of this junk science once and for all. Let’s not let our criminal justice system be placed in the hands of amateurs. If we are going to use dogs to discriminate between one human’s scent and another’s, let’s put the method through rigorous controlled scientific validation.

And let’s have some standards and practices in place.

1 comment:

被リンクサービス said...

dog is able to discriminate between the scents of one human and another?

That's my first time to hear about that, too surprise.