Fuzzy Probable Cause

Police dogs and searches


Imagine that a police officer, after searching someone's car, is asked to explain why he thought he would find contraband there. "A little birdie told me," he replies. Most judges would react with appropriate skepticism to such a claim. But substitute "a big dog" for "a little birdie," and you've got probable cause. 

Or so says the U.S. Supreme Court, which in February unanimously ruled that "a court can presume" a search is valid if police say it was based on an alert by a dog trained to detect drugs. The Court thereby encouraged judges to accept self-interested proclamations about a canine's capabilities, reinforcing the common use of dogs to justify searches despite evidence indicating they are much less reliable than commonly believed.

Instead of requiring police to demonstrate that a dog is reliable, the Court's decision in Florida v. Harris puts the burden on the defense to show the dog is not reliable through expert testimony and other evidence that casts doubt on the training and testing methods used by police. But such evidence may be hard to come by. Many police departments simply do not keep track of how often dog alerts lead to unsuccessful searches, and the Court said they are not required to do so. Even the question of whether a dog did in fact alert may be impossible to resolve if there is no video record of the encounter, which is often the case. 

The Court previously has said that police may use drug-sniffing dogs at will during routine traffic stops and may search cars without a warrant, based on their own determination of probable cause. Now that it has said a dog's alert by itself suffices for probable cause, a cop with a dog has the practical power to search the car of anyone who strikes him as suspicious.

But not his home. In Florida v. Jardines, decided a month after Harris, the Court ruled that deploying a drug-sniffing dog at the doorstep of a house amounts to a search under the Fourth Amendment, meaning police cannot do so whenever they feel like it. That ruling is especially important in light of Harris, which implies that police can get a search warrant for a house simply by claiming that a dog alerted to it.