Professor Sherry Cobb has posted the following article:

Who’s a Good Boy? US Supreme Court Considers Again Whether Dog Sniffs Are Searches

The US Supreme Court is currently considering whether to grant review in Edstrom v. Minnesota. The case presents the issue whether police must obtain a search warrant before bringing a trained narcotics dog to sniff at a person’s door for illicit drugs. The Minnesota court held that police need no warrant, and the petitioner (as well as amici in the academy) have challenged that conclusion. In this column, I will consider some of the most interesting arguments that bear on the issue that may come before the Court.

Dog Sniffs and Prior Cases

The Supreme Court has previously had occasion to rule on the constitutional significance of a dog sniff for contraband. In United States v. Place, the Court said (in dicta) that a trained police dog may sniff at a suspect’s suitcase without triggering application of the Fourth Amendment. The Court explained that a dog sniff exposes only the presence or absence of contraband and is accordingly unintrusive. Under Katz v. United States, as subsequently interpreted, police need no warrant, no probable cause, and no reasonable basis for investigating, in the absence of a reasonable expectation of privacy that police intend to infringe.

The dicta became holding in Illinois v. Caballes. The Court there held that police may, without a warrant or probable cause, deploy a trained narcotics dog to sniff at—and thereby expose the presence of contraband within—a vehicle. The Court said that people lack a reasonable expectation of privacy in the fact that they possess contraband, the only fact that a dog sniff of the kind at issue might disclose. An earlier case, United States v. Jacobsen, unrelated to dogs, had similarly approved of investigative measures that precisely expose a guilty fact about a suspect’s property with only minimal interference with property or privacy.

After these cases came down, it seemed that a dog sniff—assuming no physically intrusive behavior by the dog (or human)—fell outside the scope of Fourth Amendment protection. In Florida v. Jardines, however, things took a surprise turn. There the Court held that police had violated the Fourth Amendment when a trained narcotics dog whom they brought to the door of a suspect’s home moved around the front door in a lively fashion to trace the smells coming out of the house, all without a warrant. In a concurrence in the judgment, Justice Kagan said that we should view the trained narcotics dog as analogous to a piece of technology, and the Court had already held in Kyllo v. United States that using technology unavailable to the general public to detect what is happening inside a home constitutes a “search” for Fourth Amendment purposes, presumptively requiring a warrant.