To say the least, that would make cross-examination more difficult.
At the Texas prosecutors' user forum, we find a discussion of "scent lineups", including case law on their legality, begun by a commenter from Bryan:
My department is researching "police" bloodhounds, specifically the use of scent evidence lineups in criminal cases. If anyone knows where I can find case law and/or citations on this topic it would be greatly appreciated. Personal opinions on this topic are welcome too.An ADA from Parker County chimed in with some personal background:
As an intern in the Fort Bend County DA's office, i got to write the appellate brief on Marcus Omar Winston v. State. 78 S.W. 3d 522. At the time, Texas had very little case law about scent hounds that were not drug dogs and as such, much of my research involved out of state case law. The Houston Court published the opinion and its holding is still good law.Discussion on the string centered around Deputy Keith Pikett out of the Bend County Sheriffs Office. I'd not heard of Mr. Pikett's dogs, but a quick Google found they've earned some measure of regional renown.
They've also drawn litigation from those who question whether it's Pikett or the dogs doing the leading. A judge in January refused to dismiss Pikett from civil litigation that alleges he led his dogs to a suspect in Victoria by re-scenting them near a location targeted by local police. The lawsuit accuses Pikett and the Victoria PD of using "contrived and unreliable methods ... to create evidence" in a murder case.
Looking around for scientific evaluations of dog-scent evidence, I didn't find much. Here's a description of a "scent lineup" involving Pikett's dogs from the Austin Statesman a couple of years ago (5/15/07):
What little research-based analysis I could find online did not support dog-scent evidence having a scientific basis, though Texas courts appear to allow it. This paper from 1999 concluded that:
A police officer went to [defendant Reginal] James’ jail cell and lightly touched his skin with a gauze pad. Then Hawthorne called Pikett and told him he needed to see him soon.
The detective took the sample from James in a Ziploc bag and started the three-hour drive to meet with Pikett. He also took four other gauze pads that had been wiped on the woman’s bed, her ring, her dresser and a doorway.
In the lineup, the dogs’ job was to see if the samples from the crime scene matched the sample from James.
The lineup consisted of six cans about 10 feet apart — one had a sample from James, and five contained gauze with the scents of people unrelated to the case.
The dogs were then given the scent from one of the crime scene samples and went to the cans to see if there was a match. The process was repeated for each sample from the crime scene.
Both dogs — Quincy and James Bond — matched James’ scent to the crime scene in all four tests.
Canine identification of human scent does not yet have a proper scientific foundation ... however, such expertise should not be called junk science" in general.Interesting stuff - I'd never heard of "scent lineup" before and wonder what is the real-world error rate and to what extent the technique would hold up to scientific scrutiny?
The method has been introduced into trial proceedings too early, by overly hasty police practitioners which have caused miscarriages of justice. Moreover, there have been no field studies. ... In this situation the criteria of "scientific evidence" like those in Daubert, are of great importance. ... After all, nobody should be convicted solely on the basis of a dog wagging its tail.
RELATED: From Fortune Magazine, "Sit, Stay, Testify!"
MORE: In the comments, a reader suggests looking at the Wikipedia entry for "Clever Hans," and indeed it appears to be on point. The entry begins:
For these reasons, blind administration would be critical for "scent lineups" to be valid. If the dog handler knows ahead of time which choice contains the scent of the suspect, it would be easy for dogs to pick up on nonverbal cues - like Clever Hans did with his trainer - instead of reacting solely to a similar scent. And since the dog can't be cross examined, no one can know why the animal made the choices it did. This is poor evidence, particularly if used without blind administration.
Clever Hans (in German, der Kluge Hans) was a horse that was claimed to have been able to perform arithmetic and other intellectual tasks.
After formal investigation in 1907, psychologist Oskar Pfungst demonstrated that the horse was not actually performing these mental tasks, but was watching the reaction of his human observers. Pfungst discovered this artifact in the research methodology, wherein the horse was responding directly to involuntary cues in the body language of the human trainer, who had the faculties to solve each problem. The trainer was entirely unaware that he was providing such cues.
In honour of Pfungst's study, the anomalous artifact has since been referred to as the Clever Hans effect and has continued to be important knowledge in the observer-expectancy effect and later studies in animal cognition.