Tuesday, September 8, 2009

Drug Dogs and Fingerprints and Other Myths of the Law

Really, it was just one small case. They shipped four crates filled with marijuana from Arizona to Ohio. First one drug dog alerted. Then another did. The delivery was monitored. The guys paid for the shipment and picked it up. Then they got picked up. The marijuana was weighed and analyzed, the packaging was examined. Tried. Convicted. Affirmed on appeal. Ho hum.

Of course, sometime between the weighing and the trial someone stole a whole lot of the dope from the dopes at the sheriff's department, but that's only what makes the case fun, not what makes it interesting. What makes it interesting is the quasi-science. The case is State of Ohio v. Carlos C. Torres, Jr., out of Huron County, Ohio, and it's a model of how we rely on what's nonsense in order to ensure convictions.

Take those drug dogs. Their alerts to the package is what allowed the sting (and therefore the prosecution) to go forward. Here's what the court of appeals said in summarizing the dog testimony.
On September 17, 2007, four crates stamped "COMP. COMPONETS [sic]" were dropped off at the freight dock of R & L Carriers ("R & L") in Phoenix, Arizona, for shipment to the R & L terminal in Norwalk, Ohio. Because it was a "dock pickup,"
being shipped to appellant, the manager of the Phoenix terminal suspected that they
might contain illegal drugs. Therefore, he contacted the Phoenix Police Department,
which took one of its drug sniffing dogs to the R & L terminal. The dog alerted to the
presence of drugs in the crates.
. . .
On September 20, 2007, the crates arrived at the Norwalk terminal. James
Larand is the manager of Norwalk R & L terminal. When the crates arrived, he had a
tractor trailer take them to the local airport and followed them in another motor vehicle. At the airport, a second drug dog sniffed the crates and gave an alert that indicated that drugs were in the crates. A search warrant was obtained, the crates were opened, law enforcement officials "looked inside," saw green vegetation, and smelled "raw marijuana."
Got that. The first dog "alerted to the presence of drugs." The second dog's alert "indicated that drugs were in the crates." No and no.

I'm no expert, but you don't have to be. I don't know anything about the credentials of these particular dogs. (If you didn't know, drug dogs go to school to learn to be drug dogs. When they graduate and pass the relevant tests, they get certified. Every however often, they have to go back to get their certification renewed.) But I'll just assume they're the best darned drug dogs in the country, perfectly trained, passed their tests with flying colors. Doesn't matter. Even that brilliant dog can't do what the court said these dogs did.

Dogs do not, repeat not, alert to the presence of drugs. They alert (if properly trained) to pheremones, chemical traces emitted by drugs into the atmosphere. A dog's alert indicates, at most, that chemical traces of drugs linger in the vicinity of the place of the alert. Maybe drugs are there. Maybe drugs were once there. Maybe drugs were once really close.

Do a human version of the test. Eat a lot of garlic at dinner. Don't brush your teeth. Your breath smells of garlic in the morning. Does that mean you have garlic in your mouth? Do another test. Get a non-smoker to stay in a hotel's smoking room. The next day, smell the non-smoker's clothing. It smells of tobacco smoke. That's how it works.

It's actually possible to be intellectually honest about this, but if you are, then you have to acknowledge what the courts won't: A drug dog's alert may be a reason to think there might be drugs around, but it is simply not evidence that there are drugs around.

Then there are the fingerprints.
Earl Gliem, a forensic scientist specializing in the field of finger and handprints, testified, to a reasonable degree of scientific certainty, that the fingerprint of appellant's right index finger was on one of the black garbage bags that encased the marijuana.
It's an interesting claim, supported by, it would appear, Gliem's personal belief in his competence and everyone's assumption that he must know what he's talking about. After all, they're fingerprints.

Except there is no "reasonable degree of scientific certainty" in fingerprint identification. Why not? Because there's no known error rate because nobody's done the testing. Why not? Because the testing that's been done tends to indicate that fingerprint examiners don't know what they're doing. See, for instance, here and here, and for the most recent example of botched fingerprint identification here.

The myth of fingerprints is just that, a myth conjured up by fingerprint examiners who declare themselves infallible. They are no more than trained lookers. And what is true of fingerprints is true of tire tracks and bite marks and ballistic and hair comparisons and all the other forensic matching and comparison based on looking at two things and saying the one caused or matches the other. Maybe, and maybe not. But there are no standards, no fair measure. We're simply to trust.

Don't believe me, a simple criminal defense lawyer? Fair enough. How about a distinguished panel of scientists of the National Research Council who did a study commissioned by Congress? They said the same thing.

None of this would have made a difference to Mr. Torres. The dog sniff and fingerprint evidence was, frankly, no more than incidental to his conviction. All the more reason, then, to get it right.


  1. Counselor:
    Fingerprints are a valuable identification tool used tens of thousands of times a day for public safety to process arrest cards, background checks as well as to establish identity with unknown deceased cases. What your referring to is how the fingerprint discipline is utilized in the identification of unkown fingerprints from a crime scene. Even critics of the discipline agree that fingerprint identification is a legitimate means of identification, they disagree on what or how many points constitute an identification.
    The beauty of our judicial system is that if an error does occur, it should be detected in our adversarial system of justice. As a defense attorney you have the ability to have the fingerprint evidence evaluated by an unbiased expert to insure accuracy. I do agree far to many fingerpint errors made and there are many reasons reasons that an error occurs as NRC points out, in the interim the best way to prevent miscarriages of justice is for the defense attorney to have the fingerprint evidence evaluated. I don't mean to minimize the importance of the latent fingerprint community to work to improve the accuracy and training of latent examiners but that process will take many years. You did make some very good points and discussing the subject can only help in getting a better system.

  2. Bob,

    Thanks for your thoughtful comments.

    First, you're right that I'm talking primarily about fingerprint identification based on latent prints matched against carefully made exemplars. But even matching exemplars against exemplars can be problematic when there's no established and verified standard including an acknowledgment of an error rate.

    Some errors are simple human mistakes (which fingerprint examiners too often deny are possible - I've got transcripts of testimony from examiners who say, with all unshakeable certainty, that when they have determined that this print belongs to that person and, as one put it, "cannot belong to any other person in the world," then it must be he.

    Some errors are functions of sloppy protocols (double blind testing would really be a good thing) and even sloppy exemplars and imperfect technology.

    But without validation studies, we don't really know for sure that all fingerprints are unique. And we don't know how many points there should be for an identification. And we don't know the error rate.

    Finally, I'm just not convinced that the judicial system is up to the task of consistently separating accurate identification from inaccurate. Warring experts don't necessarily lead to accurate judgments. Juries and judges get it wrong. Defense counsel too rarely have the resources they need, and too often don't have the wisdom to know what they need or how to use it effectively when they get it.

    And, of course, if we don't have proper standards and measures, then my expert's opinion is no better - and no more reliable - than the state's.

    I don't think fingerprints are worthless, but I think there's a long way to go before they're as valuable as they're generally understood to be: the gold standard by which everything else is measured.