Drug Detection Dogs Are Barely More Accurate Than a Coin Flip

We can all agree that illegal drug use and abuse is a serious concern. And most would agree that we should take measures to foster a drug-free environment in our communities. So what is the problem with searches that use "drug detection dogs"? Aren’t drug dogs just a tool to help the police target drug users and suppliers? They won’t cause any harm to people who aren't in possession of illegal drugs, so no need for us to worry about them. Right?

Not exactly. There are a number of reasons we should be concerned about drug-sniffing dogs being used in searches, but one key problem is that they have not been very effective at targeting only drug possessors. Several studies have indicated that drug dogs are prone to false alerts, which then lead to unjustified searches. Records of drug-sniffing dogs in one Washington school district indicated that dogs were incorrect 85 percent of the times they alerted to a substance. A Chicago study of drug dogs used for roadside automobile searches shows a 56 percent error rate - increasing to 73 percent for Hispanic drivers. Even the most generous estimates suggest that drug dogs are reliable, at most, 70 percent of the time (and this figure takes into account the 26% of searches where no substances are actually found but the targeted person admits to prior drug contact).

The Chicago Tribune sifted through three years worth of cases in which law enforcement used dogs to sniff out drugs in cars in suburban Chicago. According to the analysis, officers found drugs or paraphernalia in only 44 percent of cases in which the dogs had alerted them. When the driver was Latino, the dogs were right just 27 percent of the time. The paper explains.

The Tribune spoke to a few dog experts and they almost universally blamed the handlers: Dog handlers can accidentally cue alerts from their dogs by leading them too slowly or too many times around a vehicle, said Lawrence Myers, an Auburn University professor who studies detector dogs.

The U.S. Court of Appeals for the Seventh Circuit issued a troubling ruling about drug dogs in July 2015. U.S. v. Bentley is just the latest in a series of rulings in which the federal courts refuse to consider the possibility that police departments may be manipulating the dogs to authorize unlawful searches. The problem here is that invasive searches based on no more than a government official’s hunch is precisely what the Fourth Amendment is supposed to guard against. Unfortunately, the way the U.S. Supreme Court has ruled on this issue not only doesn’t account for the problem, but also has given police agencies a strong incentive to ensure that drug dogs aren’t trained to act independently of their handler’s suspicions. A dog prone to false alerts means more searches, which means more opportunities to find and seize cash and other lucre under asset forfeiture policies. In fact, a drug dog’s alert in and of itself is often cited as evidence of drug activity, even if no drugs are found, thus enabling police to seize cash, cars and other property from motorists. Some dog trainers have said that drug dogs can be trained to alert only when there are measurable quantities of a drug - to ignore so-called "trace" or "remnant" alerts that aren’t cause for arrest. But these trainers also say that police agencies don’t want dogs trained to ignore remnant odors, because any alert is an authorization for a more thorough search.

Why do False-Positives Happen?

False positives may - as police claim - be caused by odor from previous contact with drugs, or drugs that have been stashed in an unsearched area.

But the dogs can also be affected by the context; they can become tired, hungry, or confused by multiple odors, noises and distractions.

And it is very likely that intentional and unintentional cues by dog handlers, who are trained to profile people based on behavior, appearance and comportment, are to some degree interfering with the dogs’ identifications.

Dogs are naturally responsive to even the subtlest of human cues. Scent-detection dogs were found to be more likely to falsely alert to locations when their handler believed drugs to be present, with handler beliefs influencing dog alerts even more than food decoys.

Such cues may also be exacerbating the discriminatory impacts of general drug-detection dogs.

I love dogs, and I believe that they have a strong place in police and security work. On patrol, apprehending violent criminals, and in search and rescue work dogs are first rate. But when it comes to conducting searches based on a detection rate that is little better than a coin flip, we need to ask if we are doing the right thing.

References

Illinois State Police Drug Dog Unit Analysis Shows Error Rate Between 28 and 74 Percent

Drug-Sniffing Dogs in Schools Make Every Student a Suspect

Drug-Sniffing Dogs Are Wrong More Often Than Right