The U.S. Supreme Court will soon determine whether a trained narcotics dog’s sniff at the front door of a home constitutes a Fourth Amendment search. The case, Florida v. Jardines, has privacy scholars abuzz because it presents two possible shifts in Fourth Amendment jurisprudence. First, the Court might expand the physical spaces rationale from Justice Scalia’s majority opinion in United States v. Jones. A favorable outcome for Mr. Jardines could reinforce that the home is a formidable privacy fortress, protecting all information from government detection unless that information is visible to the human eye.
Alternatively, and more sensibly, the Court may choose to revisit its previous dog sniff cases, United States v. Place and Illinois v. Caballes. This precedent has shielded dog sniffs from constitutional scrutiny by finding that sniffs of luggage and a car, respectively, did not constitute searches. Their logic is straightforward: since a sniff “discloses only the presence or absence of narcotics, a contraband item,” a search incident to a dog’s alert cannot offend reasonable expectations of privacy. Of course, the logical flaw is equally obvious: police dogs often alert when drugs are not present, resulting in unnecessary suspicionless searches.
Curiously missing from any Supreme Court opinion is a reflection on how contraband-detecting dogs fundamentally change law enforcement. Police dogs are old technology, but their widespread use ushers in a new model of policing. Like pattern-based data mining, dog sniffs produce tradeoffs inherent in dragnet-style law enforcement. They redistribute the burden of unproductive searches from the few-but-stereotypically “suspicious” to the entire population.
A Fourth Amendment search surely took place on the porch of Mr. Jardines’s Miami home. Dogs are error-prone, and Franky (the chocolate Labrador in Jardines) is no exception. The Miami police unit had no policy to ensure the equitable use of dog sniffs. Since the police were motivated by an anonymous, unverified report, using the dog was an act of discretion as opposed to evenhanded random deployment. Moreover, the introduction of a dog to a person’s property is arguably humiliating and intrusive, as the Florida Supreme Court described.
Jardines offers the Court an opportunity to carefully assess a mode of policing that subjects all constituents to the burdens of investigation and punishment, not just the “suspicious.” Today, drug-sniffing dogs are unique law enforcement tools that can be used without either individualized suspicion or a “special needs” checkpoint. Given their haphazard deployment and erratic performance, police dogs deserve the skepticism many scholars and courts have expressed. But the wrong reasoning in Jardines could fix indefinitely an assumption that police technologies and civil liberties are always at odds. This would be unfortunate. New technologies have the potential to be what dogs never were—accurate and fair. Explosive detecting systems may eventually meet the standards for this test, and DNA-matching and pattern-based data mining offer more than mere hypothetical promise. Responsible use of these emerging techniques requires more transparency and even application than police departments are accustomed to, but decrease in law enforcement discretion is its own achievement. With luck, the Court will find a search in Jardines while avoiding a rule that reflexively hampers the use of new technologies.