In the event that a drug-sniffing dog is alerted to someone’s car, more often than not there are no drugs nor any drug paraphernalia:

The dogs are trained to dig or sit when they smell drugs, which triggers automobile searches. But a Tribune analysis of three years of data for suburban departments found that only 44 percent of those alerts by the dogs led to the discovery of drugs or paraphernalia. {…}

Dog-handling officers and trainers argue the canine teams’ accuracy shouldn’t be measured in the number of alerts that turn up drugs. They said the scent of drugs or paraphernalia can linger in a car after drugs are used or sold, and the dogs’ noses are so sensitive they can pick up residue from drugs that can no longer be found in a car.

But even advocates for the use of drug-sniffing dogs agree with experts who say many dog-and-officer teams are poorly trained and prone to false alerts that lead to unjustified searches. Leading a dog around a car too many times or spending too long examining a vehicle, for example, can cause a dog to give a signal for drugs where there are none, experts said.

On the face of it, 44% sounds pretty bad. Reason, with their typical sense of perspective, says “a drug-sniffing coin would be cheaper.” Well, only if you disregard what that 44% figure actually means. Given that the actual number of cars with drugs is exceedingly low, a dog-sniff being correct nearly 50% of the time actually isn’t all that bad. If 1% of cars had drugs (a high estimation, for sure), and you cointested 200 cars, a coin would would falsely implicate 99 cars for ever 1 it actually finds drugs in. A dog would alert two cars, one of which would have drugs. I recognize that Sallum is being hyperbolic, but he’s pretty much stretching it beyond all reason.

Now, because dogs are right a little less than half of the time, should that legally justify probable case? I really don’t know. Does anyone know how the law would treat tips from an informant who is right a little less than half the time? I’d consider such an informant to be reasonably reliable. On the other hand, with that human informant you would need a judge and a warrant involved. Maybe the cops should have to call up a judge to sign off on the barking dog?

I know that I would be pretty pissed if cops were taking my car apart for an hour because of some false positive. And heaven knows, Hit Coffee is often unfriendly to law enforcement in general. But I do think that we have to keep things in perspective here and not compare this to a coin-flip or police dogs assaulting people.


Category: Courthouse

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2 Responses to Sniffing False Positives

  1. Transplanted Lawyer says:

    Oh, I see what you did there. The dogs’ accuracy rate a little bit less than 50%, and “more likely than not” is one way to define “probable.” Therefore a signal from a dog cannot, by definition, be “probable” cause. Note (and I think you do) that quantified examination of accuracy is not the only way a court might define “probable cause.”

    Unfortunately for Sullum’s critique, the Constitutional standard for most roadside vehicular searches is “reasonable suspicion” and not “probable cause.” 44% accuracy may not be “probable cause” but it is hard to say it isn’t “reasonable suspicion.”

    What’s more, the nature of a vehicle as inherently asportable (it moves under its own power) means that pretty much anything involving a vehicle presents an “exigent circumstance” of easily-destroyed evidence.

    Reasonable suspicion plus exigent circumstance means the cop doesn’t need a search warrant or even a Miranda warning to conduct a search if he feels like it, and any evidence he gathers from that search is likely going to be admissible later.

    The dog is really a ruse here — Sullum’s argument is really about criminal procedure jurisprudence that is (in his opinion) too deferential to police power and not deferential enough to individual autonomy. The dog sniffing is simply one way to point out that what the police do is very intrusive but not always based on reliable facts.

    Until and unless the law changes (and it won’t anytime soon), should you be pulled over, behave as follows: 1) be polite and patient with the cop, 2) volunteer no information beyond furnishing your driver’s license, vehicle registration, and proof of insurance, 3) consent to nothing, and 4) let your lawyer sort it all out with the prosecutor after the fact. Learn more here.

  2. trumwill says:

    TL, d’oh! I forgot that car searches fell more under Reasonable Suspicion. In that case, it’s pretty hard to argue that a 44% likelihood of finding something doesn’t meet that threshold.

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