Police departments in Virginia and around the country use dogs that are trained to sniff the air around vehicles and alert their handlers to the presence of illegal drugs, but a growing body of evidence suggests that these K-9 officers may not be all that reliable. The courts have ruled that an alert from a K-9 police dog gives police the probable cause they need to search a vehicle without a warrant, but some studies have shown that drugs are only discovered in about 25% of these searches.
False alerts 74% of the time
When officials in Australia studied thousands of police searches that were conducted after a K-9 officer alerted to the presence of a controlled substance, they discovered that no drugs were found 74% of the time. In some parts of the country, the false positive rate was as high as 82%. Some canine behavioral experts are unsurprised by these findings because dogs try to please their handlers. They say this could lead them to respond to subtle, and sometimes unintentional, human cues instead of the smell of narcotics.
Other experts question the way police dogs are trained. It is not unusual for K-9 officers that received perfect scores in training to routinely fail in the field. A police dog in Washington that passed its training with a 100% success rate alerted to drugs every time it sniffed the air around a car. Police only actually discovered drugs in 29% of these searches. Results like this have prompted groups calling for criminal law reform to ask the courts to reassess their stance on the reliability of police dogs and the quality of the probable cause they provide.
If you are charged with drug possession following a search that was triggered by a police dog, an experienced criminal defense attorney may advise you to remain silent until they have had a chance to study the facts. This is because the Supreme Court has ruled that this type of vehicle search is unconstitutional if a traffic stop is delayed unreasonably to give K-9 units time to reach the scene.