It is commonplace for police to call in the K9 unit when they suspect someone of possessing illegal drugs. However, recent reports show that drug sniffing dogs are not as reliable as advertised.
Findings show that most drug sniffing dogs have more desire to satisfy their handler than accurately detect drugs. The are more inclined to react to its handler’s body language towards a suspected drug carrier. According to the Washington Post, “This has been confirmed by tests of K9 units that have shown that controlled tests designed to fool handlers are much more likely to trigger false alerts than controlled tests designed to fool the dog.”
Naturally, this discrepancy shows itself when minorities come into the equation. In 2011, an investigation by the Chicago Tribune found that while 44% of alerts from drug sniffing dogs were accurate, that number fell to 27% with stops of Hispanic drivers. Mexican American Legal Defense and Educational Fund attorney Virginia Martinez said, “We know that there is a level of racial profiling going on, and this is just another indicator of that.”
The following was also included in that report:
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.
Myers pointed to the “Clever Hans” phenomenon in the early 1900s, named after a horse whose owner claimed the animal could read and do math before a psychologist determined the horse was actually responding to his master’s unwitting cues.
Nevertheless, according to a unanimous 2013 Supreme Court ruling, police don’t even have to prove that their dog’s drug detection capabilities are accurate to use its alert as probable cause for a vehicle search.