The U.S. Supreme Court Considers Dog Sniffs and the Fourth Amendment

This is Part One in a two-part series of columns.  Part Two in the series will appear here on Justia’s Verdict on Wednesday, November 7. –Ed.

On Wednesday, October 31, the U.S. Supreme Court will hear argument in two Fourth Amendment cases from Florida.  The cases both revolve around the constitutional significance of police dog sniffs for narcotics.

One case, Florida v. Jardines, focuses on the preliminary question of whether a police dog sniff itself invades Fourth Amendment privacy and thus constitutes a “search” for constitutional purposes.

The second case, Florida v. Harris, turns to the evidentiary significance of a positive alert after a dog sniff for narcotics has occurred.

In this column, I will examine some of the main factors that may prove salient in the two cases, and I will suggest that the Court’s analysis might benefit from an appreciation of what distinguishes dogs from inanimate, evidence-gathering machines.

The Background Facts of Jardines and Harris

In each of the two cases before the Court, a dog who assisted police in identifying narcotics communicated to his handler that he had sniffed contraband.

In Jardines, the dog in question, named “Franky,” walked up to the front door of a house that was suspected of containing narcotics and indicated (by sitting in front of the door) that he did, indeed, smell the odor of drugs coming from inside the house.

In Harris, the dog in question, named “Aldo,” sniffed the exterior of a truck that was suspected of containing contraband, after which he communicated a positive alert to the door handle of the driver’s side of the truck.

In Jardines, the reliability of Franky’s responses to narcotics appears uncontested.  The legal issue is therefore whether, in the absence of individualized suspicion, police may legally approach the door of a suspect’s private residence with a dog who has been trained to detect narcotics.  Stated differently, the Court will address the question whether a person has a reasonable expectation of privacy in not having a police dog approach his house, detect, and convey to police the fact that the house contains contraband.

The Florida Supreme Court held that a person does have this expectation of privacy, and that police must therefore have probable cause before subjecting an individual’s home to a narcotics dog sniff.

In Harris, the Fourth-Amendment legality of performing the dog sniff near the lawfully stopped vehicle appears uncontested.  What the Court must decide here is, accordingly, when a dog’s alert to drugs provides an officer with probable cause to believe that drugs are actually present.

How closely, then, should courts scrutinize a dog’s reliability at detecting narcotics, in determining whether a dog’s positive alert provides probable cause for a search?  Is it enough for the dog’s handler to testify that the dog is certified for narcotics detection?  Or must there be a detailed record showing that the dog has repeatedly and accurately discriminated between places that do, and places that do not, contain narcotics?

In the particular case, the handler who worked with Aldo—the dog in question—did not present evidence of Aldo’s error rate, so it was difficult to assess with any precision how likely he was to alert to drugs where there were actually no drugs to be found.  In other words, the government did not introduce evidence as to how often Aldo’s sniffs yielded false positives.

Further complicating matters in Harris are three facts.  First, Aldo gave a positive alert to the same driver’s side door of Harris’s truck on a subsequent occasion (two months after the stop at issue in this case), but no illegal substances were found in the truck.  This error suggested that Aldo may be prone to giving “false positive” alerts to contraband.

A second fact, which may explain the first, is that dogs are often able to detect drug residue – the tiny amount of narcotic, for example, that might be present because someone who recently used drugs touched the car door.  The dog, in such a scenario, would not technically be erroneously identifying drugs but would be providing a “false positive” in the sense that the sniffed vehicle does not contain a legally cognizable quantity of drugs.

Third, and finally, the dog in Harris was trained to detect methamphetamine but not, so far as the evidence indicated, to detect the precursors to methamphetamine, such as the pseudoephedrine pills that were found in the truck that police searched.

An inquiry into a dog’s skill in narcotics detection might therefore need to specify both the quantity and the particular substances that the dog has become skilled at detecting, in order to ensure that the dog’s positive alert corresponded to a drug for which police were searching, and in the quantity that would need to be present to violate the criminal law.

None of this information about error rates and training was available to the courts in Harris, and according to the Florida Supreme Court, it should have been.

Jardines, the Dog Sniff Cases, and the Home

The general version of the question that faces the Court in Jardines—whether a dog sniff invades any reasonable expectation of privacy—is one that has faced the U.S. Supreme Court a number of times in the past.  Each time, the Court has said, either in holding or in dicta, that people lack any reasonable expectation of privacy in the only fact that is revealed by a dog sniff—the fact that they are (or are not) in possession of contraband.  Because the narcotics dog sniff exposes only the fact that the search target either does or does not have narcotics in his possession, the Court has found that a dog sniff does not invade any reasonable expectation of privacy and is therefore not a Fourth Amendment “search.”

Accordingly, the Court has held that dog sniffs may occur in the absence of a warrant, probable cause, or indeed any individualized suspicion.  From these cases, including United States v. Place and Illinois v. Caballes, one might infer that the Florida Supreme Court erred in finding a Fourth Amendment search in Harris.

On the other hand, the Court has consistently treated the home as a sacrosanct zone for Fourth Amendment purposes.  In 2001, in Kyllo v. United States, for example, the Court said that using a thermal-detection device to register heat waves emanating from a home invaded a reasonable expectation of privacy.  This was true, the Court reasoned, notwithstanding the fact that the thermal detection device used would reveal very little about the activities within the home beyond the fact that heat lamps associated with the indoor cultivation of illegal drugs might be present.

Going further back in time, in Arizona v. Hicks, the Court ruled that police officers who were legitimately present inside a person’s home could not lawfully move a stereo component slightly, in an effort to expose the serial number, in the absence of probable cause to support a search.  The Court there said that in the home, “[a] search is a search, even if it happens to disclose nothing but the bottom of a turntable” and that “[a] dwellingplace search, no less than a dwellingplace seizure, requires probable cause.”

Moving even further back in time, in Payton v. New York, the Court held that police must obtain an arrest warrant to arrest an individual at home, even though they could have arrested the same individual in public without any warrant, simply on the basis of probable cause.  The reason for the distinction, the Court indicated, was the invasion of privacy that inevitably accompanies a home arrest, but not a public arrest.

In Welsh v. Wisconsin, the Court rejected the decision of police officers to enter a suspect’s home to arrest him without a warrant for a minor offense, in spite of the facts that (1) there was arguably an exigent circumstance making it impractical to seek a warrant ahead of time, and (2) the Court later held that arrests for minor offenses are consistent with the Fourth Amendment, even when—as in Atwater v. Lago Vista—the arrestee’s offense carries no potential jail time, and even when—as in Virginia v. Moore—state law designates the crime as a “no arrest” offense.

Taken together, these cases might lead a reader of Supreme Court precedent to conclude that “[i]n the home,” as Justice Scalia said for a majority in Kyllo, “our cases show, all details are intimate details.”

If that is the case, then perhaps even the fact that there are narcotics in the house—if not apparent to passersby without the assistance of a dog trained to detect narcotics—is a “private” fact for Fourth Amendment purposes.  And this conclusion would lead the Court to affirm the Florida Supreme Court’s ruling in Jardines.

Part Two in this series will appear here on Justia’s Verdict on Wednesday, November 7.