Justices Weigh Privacy in Police Dog Search Cases

October 31, 2012
Guest Post

By J. Amy Dillard, Associate Professor of Law, University of Baltimore School of Law


This morning, the U.S. Supreme Court will hear two cases that address whether the sniff of a dog constitutes a search of a home under the Fourth Amendment and whether a trained drug-sniffing dog’s “alert” gives probable cause for a warrantless search of a vehicle. 

Where citizens have very low expectations of privacy like the exterior of luggage in an airport terminal, the Court has held that the warrantless sniff of a dog does not violate the Fourth Amendment. But in Florida v. Jardines, a trained police dog, without a warrant, sniffed the front porch and door of a home, where the occupant’s Fourth Amendment privacy interests were at her strongest; he alerted that drugs were within the home by sitting down at the front door. Based on the dog’s alert, police obtained a warrant to search the home and found marijuana plants. At issue in Jardines is whether the defendant had a Fourth Amendment interest in protecting the exterior of her home from a sniffing dog. In Florida v. Harris, the Court must address the reliability of a trained drug-sniffing dog and determine what evidence the government must offer of that reliability when the dog provides the fundamental piece of evidence supporting probable cause to justify a warrantless search of a vehicle. In Harris,a police officer responded to an alert by a trained police dog on the exterior handle of a vehicle and, relying on that dog’s alert, entered the vehicle without a warrant and seized drug contraband. 

The issues in Jardines are not especially novel, and the Court likely will return to its standard jurisprudence about the Fourth Amendment’s explicit guarantee of privacy inside the home and whether that guarantee can extend to the home’s exterior. Generally, that which a citizen exposes to public view is not protected by the Fourth Amendment, but when the government uses high-tech devices or, arguably, highly-trained animals that are not available to the general public to detect details about activities on the interior of the home, the government must have a warrant for the search or probable cause and an exigency to circumvent the warrant requirement. Two issues should drive the Court’s analysis – whether the front porch was an area protected by the Fourth Amendment, and whether the sniff of a drug-detecting dog constituted a search of that protected area.

The issues in Harris may require more reflection for the Court, because the government is asking for an extension of the existing “dog-sniffing doctrine.” The Court has long held that citizens have no expectation of privacy when a police dog sniffs the exterior of their vehicle in public and that an “alert” by a trained drug-sniffing dog is an acceptable factor, that can combine with other factors, to lead a police officer to conclude that he has probable cause to search a vehicle for drugs without a warrant. But in Harris, the officer relied on the “alert” from his dog as the sole basis for probable cause to search the interior of the vehicle.  Since 2005, the Court has reasoned that the sniff of a trained dog during an extended traffic stop was reasonable, but in Harris, it must decide whether that sniff is reliable. The defense raises some empirical evidence that drug-sniffing dogs are not infallible, nor are they reliable, in that they return false positives up to 60 percent of the time. The Court can easily side-step any proclamations about the objective reliability of trained drug-sniffing dogs by keeping the dog “alert” as a potentially reliable factor in its totality of the circumstances test for probable cause. 

But if the Court in Harris declares that a trained drug-sniffing dog’s “alert” can, alone, establish probable cause, then those dogs will likely become a “high-tech” police device not available to the public.  So, while the front porch of the home in Jardines might be open to public view and, by implied consent, to mailmen, inquiring police officers, or friendly neighbors, once an officer approaches that protected curtilage with a “high-tech” surveillance device, he will need to have a warrant in his hand.