Supreme Court Finds the Use of a Drug-Sniffing Dog to Investigate a Home Unconstitutional

On March 26, the Supreme Court issued its decision [PDF] in Florida v. Jardines, a case involving police use of a drug-sniffing dog on the front porch of a home to detect marijuana growing inside. In a 5-4 opinion delivered by Justice Scalia, the Court held that “the government’s use of trained police dogs to investigate the home and its immediate surroundings is a ‘search’ within the meaning of the Fourth Amendment.”

In 2006, following a tip regarding marijuana being grown in a house, Miami police brought a drug-sniffing dog to the front porch. After the dog indicated the presence of drugs, police obtained a warrant, found marijuana in the house, and arrested Joelis Jardines. At trial, Jardines claimed that the use of the drug-sniffing dog was a Fourth Amendment violation. After a trial court and then the Florida Supreme Court agreed, Florida petitioned and was then granted a Supreme Court review, and oral arguments were heard in October 2012.

The Court’s opinion in Jardines is narrowly crafted, focusing on the government’s physical intrusion into the constitutionally protected area immediately surrounding the home (called the “curtilage”) for the purposes of gathering evidence. The Court acknowledged the existence of an implicit license permitting visitors to “approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave.” “Complying with the terms of that traditional invitation,” explained the Court, “does not require fine-grained legal knowledge; it is generally managed without incident by the Nation’s Girl Scouts and trick-or-treaters.” However, there is no implicit license to introduce “a trained police dog to explore the area around the home in hopes of discovering incriminating evidence.” Since the officers were able to learn that marijuana was being grown in the home only by “physically intruding on Jardines’ property to gather evidence,” the search was unconstitutional in the absence of a warrant.

The majority opinion explicitly declined to consider whether the officers’ search of Jardines’ home violated his reasonable expectation of privacy; it was sufficient to find a constitutional violation based on what the Court characterized as “the traditional property-based understanding of the Fourth Amendment.” A concurring opinion from Justice Kagan and joined by Justices Ginsburg and Sotomayor went further. “Yes,” Justice Kagan wrote, the officers’ actions constituted a trespass. “Was it also an invasion of privacy? Yes, that as well.”

In some respects, the Jardines decision echoes the Court’s January 2012 decision in United States v. Jones [PDF], the GPS-tracking case in which Justice Scalia’s majority opinion also found a Fourth Amendment violation in the act of trespassing—in that case with respect to the physical intrusion involved in placing a GPS receiver on a car without a valid warrant. In Jones there was also a concurrence (two, in fact) suggesting that the information gathered by the government violated a reasonable expectation of privacy.

As technology continues to advance, it will become harder to rely on a property-focused view of the Fourth Amendment when assessing what constitutes a “search.” In fact it is actually the 2001 Kyllo v. United States case, and not this week’s ruling in Jardines or last year’s decision in Jones, that is in some ways more indicative of the types of complex questions the Court will grapple with in future privacy cases. In Kyllo, the Court considered the government’s use of a thermal imager in a car on a public street to detect the interior temperature of a home. There was no trespass in Kyllo, leaving the Court no choice but to evaluate the constitutionality of the government’s actions on the basis of what the technology itself could reveal. When the government “uses a device that is not in general public use,” the Court held in Kyllo, “to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a ‘search’ and is presumptively unreasonable without a warrant.”

Suppose that the police in Jardines had used the drug-sniffing dog—or, for that matter, an inanimate sensor—from the vantage point of a public sidewalk in front of the house? The majority opinion in Jardines doesn’t address this scenario. Justice Kagan and the two justices who joined her concurrence considered a trained drug-detection dog to be a device not in general public use, and on those grounds would have found its use unconstitutional in light of Kyllo. By contrast, Justice Alito and the three other dissenting justices disagreed that Kyllo was applicable in Jardines, noting that a dog is neither a new form of technology nor a device.

Technology is making it increasingly easy to access information that most of us would consider private without physically trespassing on private property. Mobile devices and apps, smart meters, and Internet histories can convey enormous amounts of information about activities both within and outside a home, all of which can potentially be accessed by third parties who never set foot in a home or its surroundings. Some of the most pressing privacy questions that will land at the Supreme Court’s feet in future years will involve exactly this sort of data, collected using technologies that are in general public use—and therefore outside the scope of the holding in Kyllo. When that happens, the Court will face the unenviable task of determining what, in today’s day and age, constitutes a reasonable expectation of privacy in light of technologies that are both highly sophisticated and widely used.