--by Sebastian H
I have a constant frustration with the legal system: that its mechanisms often cause a focus on the wrong thing. I don't mean that it focuses in areas I think are unimportant--though that happens too. I mean that even if it is looking in an important area, the structure of the legal system leads it to deal with the issue in the wrong way.
There is a certiorari petition before the Supreme Court on the question of whether or not bringing a drug sniffing dog to somone's home counts as a police search. It is a legal problem at all because using drug sniffing dogs on a person's car has been deemed "not a search" under the 4th amendment. This is a surprising result in itself, but leave that aside for the moment. So having discovered that using a drug sniffing dog around a car isn't a search, some police officer decided to use it around a house. This ends up implicating all sorts of problems, because constitutionally speaking homes are specially protected areas when it comes to police searches.
So now various high courts have to decide how to distinguish the case of the drug sniffing dog near a home from a drug sniffing dog near a car. Great. But that is the wrong question entirely. It turns out that drug sniffing dogs have an incredibly high false positive rate--they alert many more times than drugs are actually found once a search is done. Worse the dogs seem to alert much more often if their handler suspects there should be an alert--independent of whether or not there are actually drugs present. So the dog launders the police officer's suspicion instead of actually adding new information.
Dr Lit asked 18 professional dog handlers and their mutts to complete two sets of four brief searches. Thirteen of those who participated worked in drug detection, three in explosives detection, and two worked in both. The dogs had been trained to use one of two signals to indicate to their handlers that they had detected something. Some would bark, others would sit.
The experimental searches took places in the rooms of a church, and each team of dog and human had five minutes allocated to each of the eight searches. Before the searches, the handlers were informed that some of the search areas might contain up to three target scents, and also that in two cases those scents would be marked by pieces of red paper.
What the handlers were not told was that two of the targets contained decoy scents, in the form of unwrapped, hidden sausages, to encourage the dogs’ interest in a false location. Moreover, none of the search areas contained the scents of either drugs or explosives. Any “detections” made by the teams thus had to be false. Recorders, who were blind to the study, noted where handlers indicated that their dogs had raised alerts.
The findings, which Dr Lit reports in Animal Cognition, reveal that of 144 searches, only 21 were clean (no alerts). All the others raised one alert or more. In total, the teams raised 225 alerts, all of them false. While the sheer number of false alerts struck Dr Lit as fascinating, it was where they took place that was of greatest interest.
When handlers could see a red piece of paper, allegedly marking a location of interest, they were much more likely to say that their dogs signalled an alert. Indeed, in the two rooms where red paper was present and sausages were not, 32 of a possible 36 alerts were raised. In the two where both red paper and sausages were present that figure was 30–not significantly different. In contrast, in search areas where a sausage was hidden but no red piece of paper was there for handlers to see, it was only 17.
The dogs, in other words, were distracted only about half the time by the stimulus aimed at them. The human handlers were not only distracted on almost every occasion by the stimulus aimed at them, but also transmitted that distraction to their animals–who responded accordingly. To mix metaphors, the dogs were crying “wolf” at the unconscious behest of their handlers.
A tracking study was done of drug sniffing dogs in Illinois which found that the searches their 'alerts' triggered found no evidence of drugs 56% of the time. For Hispanic people searched as a result of the 'alerts' there was no evidence of drugs 63% of the time. Chicago Times
This is a problem because drug sniffing dogs are supposed to be used as a tool leading to probable cause for a search. The dog sniffs are used when the police officer does not have probable cause to search someone he is suspicious of. If the dog alerts, he now has probable cause and can search the suspect, the suspect's car, and if the state attorney general offices get their way they can search a home.
But in Illinois, a dog sniff doesn't lead to discovery of evidence of drugs even 50% of the time. Dr. Lit's experiment suggests that the false positive for the sniff alert is extremely high. Essentially the dog can pick up on the suspicions of the handler, and alerts on that basis. But if the suspicions of the police officer aren't enough for a probable cause search, they shouldn't be enough for a probable cause search when laundered through the dog 'alert' either. The dog alert is relevant only if it provides strong additional information. That is the issue which the law should be focusing on. Fine line distinctions between car 'non-searches' and house 'non-searches' are irrelevant if the dog isn't providing a reliable independent factor for probable cause.
The fact is that in Illinois (the only state to track it comprehensively) even if a police officer already suspects you of being involved in the drug trade, and then gets a drug sniffing dog out, and then the dog gives an alert, the police officer only finds drugs or evidence of drugs 46% of the time (27% of the time if you're Hispanic). If a police officer suspected a Hispanic person of being involved in the drug trade, didn't have independent probable cause for a search, but flipped a coin twice and only searched when it came up heads at least once, would we say that the coin flip produced probable cause?
See also Radley Balko on the topic in Reason earlier this year