When a person is sniffed by a drug dog, a positive response by the dog is enough to justify a further search of the person and their belongings. Based on a 2005 U.S. Supreme Court case, a dog sniff isn’t even considered a search for the purposes of the Fourth Amendment’s prohibition on unreasonable searches and seizures.
“A dog sniff conducted during a concededly lawful traffic stop that reveals no information other than the location of a substance that no individual has any right to possess does not violate the Fourth Amendment,” wrote the court at the time.
But what if the drug-sniffing dog wasn’t accurate? Multiple studies have found that drug dogs are wrong nearly 50 percent of the time — sometimes more. This trusted law enforcement resource is no more accurate than mere chance.
Unfortunately, there is substantial evidence that the drug-sniffing dogs relied on by law enforcement do have high error rates. It may be simply that properly training a drug dog is quite difficult. They need to be trained not only to detect drugs but also to overcome their ingrained desire to please their handlers.
A study in 2010, for example, tried to determine whether the dogs were alerting based on handler cues rather than the presence of actual drugs. The researchers designed packages to fool the handler into thinking there were drugs present when there were not. The drug dogs were much more likely to trigger on these packages, so the handlers were probably — perhaps subtly or unconsciously — cuing the dogs’ alerts.
Why would police use drug dogs with high error rates?
There may be real incentives for the police to continue using drug-sniffing dogs who alert falsely. For one thing, a drug dog’s alert justifies further searching, and police benefit from searching people. They sometimes find the drugs they’re looking for, and they frequently find evidence of unsuspected crimes. When they do, the courts don’t question whether the drug dog’s positive alert was accurate and rarely consider these searches to be unconstitutional.
They could create a financial incentive, too. When police discover evidence of drugs or some other criminal behavior, they can seize the suspect’s cash and property even though the suspect hasn’t yet been convicted of anything. In order to get those assets back, the suspect has to prove that they weren’t connected to crime. Otherwise, the police get to keep the assets.
Ultimately, the courts will accept the results of a drug dog’s sniff, even though the dogs may not have a good record for accuracy. Nevertheless, you should discuss whether any particular search was legal with your criminal defense attorney.