Unlike an earlier decision this term that allowed dog-sniff evidence from a traffic stop, Jardines holds that the dog-sniff search of a front porch requires a warrant.

In a recent 5-4 split decision, the U.S. Supreme Court ruled that police officers may not perform a dog-sniff search on the front porch of the home of a suspected marijuana grower without a warrant.

Although warrantless law-enforcement officers may enter the front porch of a suspect's home to knock on the door in hopes of gaining entry, the court's majority held that it violates the Fourth Amendment to perform a dog-sniff search of the property without the owner's express or implied consent to perform such activities.

The Fourth Amendment provides in relevant part that the "right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated." The Supreme Court has consistently held that a "search" takes place when the government obtains information by "physically intruding" into those constitutionally protected areas.

In Florida v. Jardines, 569 U.S. ___ (2013), the court determined that the front porch of a person's home is part of the "curtilage" of the property, and is therefore protected by the Fourth Amendment. Without either a warrant to conduct a search, or an express or implied license from the property owner to perform this kind of investigation, police officers may not use a drug-sniffing dog - or any other kind of special surveillance technology - to discover incriminating evidence.

Circumscribing admissibility of dog-sniff evidence

Illinois attorney David J. Robinson, a law clerk for Justice Robert J. Steigmann of the Illinois Appellate Court, Fourth District, said the Jardines opinion "essentially is a balancing of the Supreme Court's decision" in Florida v. Harris, 568 U.S. ___ (2013), which was also decided earlier this year. Robinson wrote about Harris in the April IBJ (Admissibility of Dog-Sniff Evidence: Evaluating Probable Cause after Florida v. Harris).

"Harris was a dog-sniff case where the Supreme Court said it's not a search when a dog sniffs a car during a traffic stop," Robinson said. "In light of Harris, I think the Jardines case is so important because [the justices] are now going to be limiting dog-sniff cases to places with less protected interests."

Robinson said the Harris decision recognized that we have a lower expectation of privacy in our vehicles than we do in our homes and on our private property. He said warrantless dog-sniff searches can take place in areas like airports, where you and your luggage can be subject to inspection, or on public roads when traveling in your vehicle.

"But when you enter onto the curtilage of a person's property, or into the private and protected areas of a home, the sniff itself becomes a search," Robinson said.

Robinson noted that the majority opinion in Jardines, written by Justice Antonin Scalia, relies primarily on the notion that this search was a trespass on constitutionally protected private property, because the police lacked any search warrant or any license from the property owner to conduct the investigation.

However, a concurring opinion drafted by Justice Elena Kagan held the search in Jardines to also be a violation of the defendant's privacy rights. The concurrence also expanded the decision by holding that a police K-9 unit is a special kind of surveillance technology that, like attaching a GPS tracking device to a person's car, must be performed under the authority of a court-issued search warrant.

"Kagan wrote for the special concurrence that they agree with [Scalia's] trespass analysis, but they also believe it was a violation of privacy interests under the Fourth Amendment," Robinson said. "Just like in [prior Supreme Court decisions], they said the dog acts like a detection device, and if the detection device is not available to the general public, then using it without a warrant violates the Constitution."

Going beyond the 'customary invitation'

In Jardines, a police officer received an unverified tip that Joelis Jardines was growing marijuana in his home. A month later, police performed surveillance at the property and, when a K-9 unit arrived, two officers and the drug-sniffing dog walked onto Jardines's front porch.

The officers did not knock on the door - rather, without any search warrant, they instructed the dog to sniff for drugs, and the dog indicated the scent of an illicit substance was emanating from under the front door of the home. Based on the results of the dog-sniff search, the officers obtained a warrant and then returned to the home, in which they found several marijuana plants.

In the majority opinion, Scalia wrote that police officers, like any other people, have an implied license to enter private property for limited purposes. There is a "customary invitation" that typically permits visitors to approach a home, knock on the door, wait to be greeted, and then to leave the property unless an express invitation to remain is granted by the owner.

"Complying with the terms of that traditional invitation does not require fine-grained legal knowledge; it is generally managed without incident by the Nation's Girl Scouts and trick-or-treaters," Scalia wrote. "But introducing a trained police dog to explore the area around the home in hopes of discovering incriminating evidence is something else. There is no customary invitation to do that."

"To find a visitor knocking on the door is routine (even if sometimes unwelcome)," Scalia continued, but "to spot that same visitor exploring the front path with a metal detector, or marching his bloodhound into the garden before saying hello and asking permission, would inspire most of us to - well, call the police."