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Criminal Law Newsletter

The Constitutionality of Using a Drug-Detection Dog During a Traffic Stop

The Fourth Amendment prohibition against “unreasonable searches and seizures” generally requires police officers to obtain a warrant based on probable cause. The warrant must meet certain requirements, including “particularly describing the place to be searched, and the persons or things to be seized.” However, in the notable 1968 case of Terry v. Ohio, the U.S. Supreme Court established an exception to the warrant requirement for investigative detentions based on less than probable cause, where a police officer has “reasonable suspicion” of criminal activity.

On January 24, 2005, the Court effectively broadened the scope of the principles set forth in Terry and its progeny in Illinois v. Caballes, upholding the constitutionality of using a drug-detection dog to locate contraband in a person’s car based on less than probable cause during a lawful traffic stop. In allowing officers to call for the assistance of a canine unit during a lawful traffic stop for a minor traffic violation, even when the officer has no reason to suspect that the vehicle contains drugs, the effects of this ruling are potentially significant.

The History of “Sniff Tests” in Airports

Although the Fourth Amendment generally protects the privacy interest of a person in the contents of their personal luggage, the Court has traditionally upheld investigative detentions of luggage at airports on less than probable cause, where an officer has reasonable belief that the luggage contains drugs. On these grounds, the Court has further extended the Terry principles to permit an officer who has reasonable belief that a traveler is carrying luggage containing drugs to subject the luggage to a “sniff test” by a well-trained drug-detection dog.

Revealing the Presence of Contraband Does Not Constitute a “Search”

Specifically, the Court held in the 1983 case of U.S. v. Place that conducting a canine sniff on a person’s luggage by a well-trained narcotics dog does not constitute a “search” under the Fourth Amendment. The Court based this conclusion on several factors, reasoning that the exposure of luggage to a trained canine:

  • Does not require opening the luggage
  • Is conducted on luggage that is located in a public place
  • Is much less intrusive than a typical search
  • Reveals only limited information
  • Does not expose non-contraband items that otherwise would remain hidden from public view
  • Discloses only the presence or absence of narcotics (a contraband item)

As using a well-trained narcotics dog to conduct a “sniff test” on a person’s luggage is “so limited both in the manner in which the information is obtained and in the content of information revealed by the procedure,” the Court concluded that exposing luggage to a trained canine is not subject to Fourth Amendment limitations.

The Length of the Detention

Although a “sniff test” based on less than probable cause can be constitutional under particular conditions, the length of the detention must be reasonable in order not to fall into the category of a “search.” In fact, the Court invalidated the search in Place because it was not “expeditious.” The agents in Place took 90 minutes to transport the suspect’s luggage to another airport for administration of the canine sniff. Reasoning that “the brevity of the invasion of the individual’s Fourth Amendment interests is an important factor in determining whether the seizure [is reasonable in the absence of probable cause],” the Court concluded that the administration of the “sniff test” in Place constituted a seizure of the suspect’s luggage that required probable cause under the Fourth Amendment.

On similar reasoning, in December 2002, the Illinois Supreme Court upheld the suppression of evidence obtained by way of a canine sniff, based in part on the duration of the traffic stop. In that case, the officer stopped the defendant’s vehicle for a minor traffic violation and called a second officer to bring his canine to the scene. The second officer arrived 15 minutes later, while the first officer was writing the traffic ticket, and walked his dog around the defendant’s car. When the dog alerted the officers to the presence of drugs, the officers searched the defendant’s car, found possible marijuana residue on the floorboard, conducted a “pat down” search of the defendant’s person and found marijuana on her person. The Court concluded that the traffic stop was “overly long” in light of its scope and purpose and suppressed the evidence found as a result thereof.

“Reasonable, Articulable Suspicion” Not Needed to Justify a Dog Sniff

In refusing to suppress the evidence obtained as a result of the “sniff test” conducted in the recent Caballes case, the Court reasoned that the Fourth Amendment does not require “reasonable, articulable suspicion to justify using a drug-detection dog to sniff a vehicle during a legitimate traffic stop” (emphasis added). The Court specifically distinguished the facts in Caballes from the aforementioned Illinois Supreme Court case, noting that the dog sniff in the earlier case had been conducted during an unlawfully long detention. In contrast, the entire incident in the Caballes case lasted less than 10 minutes. Accordingly, the Court concluded that “conducting a dog sniff [does] not change the character of a traffic stop that is lawful at its inception and otherwise executed in a reasonable manner.”

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