State Bar of California California Bar Journal
Home Page Official Publication of the State Bar of California June2004
Top Headlines
MCLE Calendar of Events
You Need to Know
Trials Digest
Contact CBJ

Dogs And Katz — What’s the Relationship?

IMPORTANT NOTICE: This article is provided solely for research and archival purposes. MCLE self-study credit is no longer available. Even if you follow the instructions and submit payment you will not be granted MCLE self-study credit. Please note that low-cost MCLE is provided by the California Lawyers Association, pursuant to Business and Professions Code section 6056.

Supreme Court will consider whether drug- or bomb-sniffing dogs violate reasonable expectations of privacy

By Alex Ricciardulli

Alex Ricciardulli
Alex Ricciardulli

In the Terminator movies, humans following a nuclear apocalypse survived only with the aid of trained dogs to detect killer robots like the one played by Arnold Schwarzenegger. In the real world, bomb-sniffing dogs might often be the only thing saving countless innocent persons from annihilation at the hands of terrorists.

The use of dogs in fact and fiction is a powerful weapon in law enforcement’s arsenal. Canines are capable of noticing smells outside the range of humans, making them as indispensable to investigators as flashlights or binoculars.

From a legal perspective, the utility of dogs is reinforced by the fact that a dog sniff has been repeatedly held to not constitute a “search,” meaning that evidence uncovered can be used against criminals without fear of suppression under the Fourth Amendment. Since sniffing isn’t a search, cases have held that police do not need warrants or even individualized suspicion of wrongdoing in order to employ dogs.

However, depending on the outcome of a case due to be heard by the United States Supreme Court this fall, the rule that a sniff is not a search could drastically change.

In Illinois v. Caballes, No. 03-923, the Supreme Court will consider head-on for the first time whether a person’s expectation of privacy is invaded by a dog’s nose. Given the nation’s heightened state of alert since the 9/11 attacks, as well as entrenched police practices in this area, it would be wise not to bet against the dogs.

A [police] man’s best friend

For starters, the high court’s past allusions to dogs and searches bode ill for the defense in Caballes.

In United States v. Place, 462 U.S. 696 (1983), the court considered the constitutionality of holding a person’s luggage for more than 90 minutes until a dog detected drugs in the bags. Place held that the seizure of the luggage was unreasonably long and unconstitutional. However, Place stated in dicta that the dog sniff did not amount to a search of the luggage, relying mainly on the fact that the bags were in a public place, and the sniff was less intrusive than actually opening the bags to see what was inside.

City of Indianapolis v. Edmond, 531 U.S. 32 (2000), held that random stops of cars at checkpoints designed to uncover narcotics were unlawful because checkpoints can only be used for purposes other than general law enforcement, such as during immigration stops or sobriety roadblocks. In Edmond, cars would be stopped and a drug-sniffing dog would alert officers regarding concealed contraband. Nonetheless, Edmond stated that “the fact that officers walk a narcotics-detection dog around the exterior of each car at the Indianapolis checkpoints does not transform the seizure into a search .  .  . Just as in Place, an exterior sniff of an automobile does not require entry into the car and is not designed to disclose any information other than the presence or absence of narcotics

.  .  . Like the dog sniff in Place, a sniff by a dog that simply walks around a car is much less intrusive than a typical search.” (Id., at p. 40.)

Lower courts have taken these statements and run with them, holding that dog-sniffs aren’t searches. Federal courts, for example, have relied on both Place and Edmond in finding that the police use of dogs did not interfere with any right of a defendant. (See United States v. Ibarra, 345 F.3d 711 (9th Cir. 2003); United States v. Seals, 987 F.2d 1102 (5th Cir. 1993).)

California courts are in accord. One of the pithiest statements on the subject came from the Court of Appeal in People v. Salih, 173 Cal.App.3d 1009, 1015, fn. 5 (1985). Distinguishing the landmark case of Katz v. United States, 389 U.S. 347 (1967), which held defendants have a reasonable expectation of privacy from government eavesdropping and other intrusions, Salih said “sniffing dogs are not controlled by Katz.”

A puppy strays from the fold

Against this monolith of opinion, the Supreme Court of Illinois’ approach stands in sharp contrast. In the case due to be heard by the U.S. Supreme Court, the Illinois tribunal held that a dog sniff is a search under the Fourth Amendment.

The defendant in Caballes was stopped for speeding by a state trooper in rural Illinois. During the ensuing detention, the officer became suspicious of the defendant because of various factors, such as the defendant acting nervous, and saying that he was moving from Las Vegas to Chicago but having no visible luggage.

The officer was writing the defendant a “warning ticket” for the speeding violation when another officer arrived on the scene with his drug-detection dog. The dog alerted to the trunk, and a search revealed marijuana.

The Illinois Supreme Court reversed the defendant’s conviction, finding that the evidence had been unlawfully uncovered. The Illinois court held that the dog sniff was an intrusion into the defendant’s reasonable expectation of privacy, and thus could not be conducted absent “specific and articulable facts” to support subjecting the car to the canine sniff. The Illinois Supreme Court concluded that there were insufficient facts to support the sniff in its case, and thus the Fourth Amendment had been violated. (Illinois v. Caballes, 207 Ill.2d 504, 509-510 (2003).)

Saying no to what the nose knows

Although virtually alone in the legal landscape, the Illinois Supreme Court’s rule finds support in academic discussions of the subject, in a concurring opinion by a justice of the U.S. Supreme Court, and in a recent Supreme Court case that ruled that mechanical devices which detect heat and other emanations through solid objects are searches: Kyllo v. United States, 533 U.S. 27 (2001).

One commentator has doubted the prevailing thought that a dog sniff does not present an intrusion into a person’s privacy, positing that “the very act of being subjected to a body sniff by a German Shepherd may be offensive at best or harrowing at worst.” (Arnold H. Loewy, The Fourth Amendment as a Device for Protecting the Innocent, 81 Mich.L.Rev. 1229, 1246. (1983).) A dog “alerts” that there is contraband afoot usually by furiously barking, sniffing and pawing, further rattling a “snifee.” (See Sandy Bryson, Search Dog Training, 302 (1988).)  

Horror stories regarding the use of dogs, such as the one documented in Doe v. Renfrow, 475 F. Supp. 1012 (N.D. Ind. 1979), are often used to reinforce objections to the unbridled use of canines. In Doe, a drug-sniffing dog “alerted” to a 13-year-old junior high girl during a school-wide sniff. The dog continued to “alert” to the girl even after her pockets were emptied and no drugs were uncovered; it turned out that she had been playing that morning with her own dog, which was in heat.

Justice Harry A. Blackmun in his concurring opinion in Place stated that due to the privacy interests involved, a dog sniff may well be a “search,” yet, acknowledging that a sniff is less intrusive than a full-blown search of a person would have held that the sniff did not need to be supported by a warrant or probable cause. Justice Blackmun suggested that all that the police would need to justify the sniff is reasonable and articulable suspicion of criminality — the very standard adopted by the Illinois Supreme Court. (United States v. Place, supra, 462 U.S. 696, 723, Blackmun, J., concurring.)

Finally, some tension exists between the dicta in Place and Edmond and the landmark opinion in Kyllo v. United States. Kyllo dealt with police use of a thermal imaging scanner to detect heat sources indicative of lamps used to help marijuana grow in a house. The court held that use of the scanner was a search which could not be performed without probable cause and a warrant.

Kyllo reasoned that “obtaining by sense-enhancing technology any information regarding the interior of a home that could not otherwise have been obtained without physical intrusion into a constitutionally protected area . . . constitutes a search.” (Kyllo v. United States, supra, 533 U.S. 27, 34.)

It could be argued that a trained dog is the biological equivalent of the device in Kyllo. The dog’s nose enhances the officer’s own senses by smelling things he cannot, and provides information which could only be uncovered if a physical intrusion had taken place.

Handicapping the dog race

The best that can be said about the Illinois Supreme Court’s approach is that it strikes a middle ground between requiring probable cause for dog sniffs and allowing them in all situations. The Illinois rule, like the tack adopted by Justice Blackmun, would require only reasonable suspicion of criminal activity in order to allow a car to be sniffed by a dog; reasonable suspicion is a lesser standard than full-blown probable cause. (United States v. Sokolow, 490 U.S. 1, 7-8 (1989).) Under established law, the police can conduct a physical search of a car, including the inside of the trunk, without a warrant. (Carroll v. United States, 267 U.S. 132 (1925); California v. Acevedo, 500 U.S. 565 (1991).) So, if the Illinois rule were adopted, police would need more than a hunch to sic the dog on the car, but definitely not probable cause, and definitely no warrant.

Even this might be too much to ask of law enforcement in the field. The facts of Caballes itself are a good illustration of the weaknesses of the rule. Admittedly the suspicious factors noted by the Illinois trooper did not amount to reasonable suspicion that the driver was a drug dealer. But having the dog sniff the car did not delay the motorist because the officer was still in the process of writing a ticket when the dog detected the marijuana. Under the Illinois rule, the trooper would have been powerless to further investigate the defendant by using the dog and would have had to let him go on his merry way.

Kyllo probably won’t help the defense much: although electronic equivalents of dog sniffs might be searches when used on people’s houses, a car isn’t a house. Precedents dating back to the Middle Ages exalt privacy in one’s home. (See Payton v. New York, 445 U.S. 573, 586 (1980).) Kyllo itself was careful to limit its holding to houses, emphasizing that its situation involved “a private home, where privacy expectations are most heightened.” (Kyllo v. United States, supra, 533 U.S. at p. 33.) Persons have far less of an expectation of privacy in cars.

The most likely outcome is that the Caballes defendant will lose, and the high court will reaffirm its statements in Place and Edmond, distinguishing Kyllo because of the lessened expectation of privacy behind the wheel. In no way, however, will that end litigation over dog sniffs.

A far different holding might ensue with body sniffs or sniffing the exterior of houses. Having a dog stick their nose on a person is a far greater intrusion, and houses receive more protection than cars.

Also, even if car sniffs are held not to be searches, it will be important in these cases to examine how the police got in position to conduct the sniff in the first place. For example, if the initial detention of a motorist was unlawful, or if it became unduly prolonged while waiting for a dog to arrive, any evidence found by the dog will still have to be suppressed. Even plain view observations — or “plain smell” ones — are unconstitutional if the police violated a defendant’s rights to be in position to make the observation. (See People v. LeBlanc, 60 Cal.App.4th 157, 166 (1997).)

The tail that wags the dog

Ultimately, legal jargon and reasoning aside, the practicalities of imposing hurdles to the use of dogs will likely be outcome-determinative. In these dangerous times, where a car bomb can spell instant doom, the intrusion of having a dog sniffing around is vastly outweighed by public safety concerns.

The court in deciding Caballes will doubtlessly have in the back of its mind Justice Robert H. Jackson’s famous admonition that the Constitution should not be turned into a “suicide pact”: “The choice is not between order and liberty. It is between liberty with order and anarchy without either.” (Terminiello v. City of Chicago, 337 U.S. 1 (1949), Jackson, J., dissenting.)

Alex Ricciardulli is a Los Angeles County deputy public defender and adjunct professor at Loyola and USC law schools. He is also co-author with Professor Laurie Levinson of “California Criminal Law” (West 2003).


  • This self-study activity has been approved for Minimum Continuing Legal Education credit by the State Bar of California in the amount of one hour of legal ethics.

  • The State Bar of California certifies that this activity conforms to the standards for approved education activities prescribed by the rules and regulations of the State Bar of California governing minimum continuing legal education.

Self-assessment test

Answer the following true-false statements after reading the MCLE article on Rule of Professional Conduct 2-100. Use the answer form provided to send the test, along with a $20 processing fee, to the State Bar. If you do not receive your certificate within four weeks, call 415-538-2504.

  1. The police greatly value the use of trained bomb-detection dogs partly because prior to the state opinion in Caballes, dog sniffs had been held to not require individualized suspicion of criminality.

  2. Even though warrants are not needed to conduct dog sniffs, courts before Caballes required probable cause to believe that the person about to be sniffed had committed a crime.

  3. Out of an abundance of caution, law enforcement presently routinely only subjects persons to dog sniffs if they have at least reasonable individualized suspicion of wrong-doing; hence the outcome of the U.S. Supreme Court’s case in Illinois v. Caballes will not have a great impact if the defendant wins.

  4. Illinois v. Caballes will allow the U.S. Supreme Court to reconsider the holding of its past cases which approved the use of dog sniffs without individualized suspicion.

  5. Although the U.S. Supreme Court in United States v. Place approved the use of a dog sniff without individualized suspicion or a warrant, the court ruled that the evidence in the case was nonetheless obtained unconstitutionally because of an unduly prolonged detention.

  6. The U.S. Supreme Court in City of Indianapolis v. Edmond indicated that having “officers walk a narcotics-detection dog around the exterior of each car at the Indianapolis checkpoints does not transform the seizure into a search,” and thus evidence uncovered in the checkpoint was obtained lawfully.

  7. Lower federal courts have relied on the U.S. Supreme Court’s discussion in Place and Edmond to hold that dog sniffs are not searches.

  8. California cases have held that dog sniffs are not searches, distinguishing a U.S. Supreme Court’s decision concerning a person’s reasonable expectation of privacy in the eavesdropping context.

  9. When the Illinois Supreme Court held in Illinois v. Caballes that a dog sniff was a constitutionally protected “search,” the case joined a growing number of state opinions that disagreed with the U.S. Supreme Court in Place and Edmond.

  10. Although the Illinois Supreme Court in Caballes found that the dog sniff of the defendant’s car was a “search,” the marijuana discovered by the dog was not suppressed because the court found that there were “specific and articulable facts” to support subjecting the car to the canine sniff.

  11. Because the manner in which a dog “alerts” when it finds contraband is by barking and pawing, even if the procedure is not a “search” under the Constitution it could constitute an invasion of a person’s privacy.

  12. A dog will sometimes “alert” to things other than illegal contraband, adding to criticism of the unbridled use of detection-dogs.

  13. Support for the approach of the Illinois Supreme Court can be found in Justice Harry A. Blackmun’s concurring opinion in Place, where he would have found that a dog sniff is a “search,” but one that need not be supported by probable cause.

  14. By granting certiorari in Illinois v. Caballes, the U.S. Supreme Court will resolve any inconsistencies between its approval of dog sniffs in Place and Edmond, and its holding in Kyllo v. United States concerning thermal imaging scanners.

  15. The holding of Kyllo that using “sense-enhancing technology” on a home is a search cannot be distinguished from the facts in Illinois v. Caballes.

  16. Because of the lessened expectation of privacy that a person has in a car, the police can conduct a physical search of a vehicle, including inside the trunk, without a warrant.

  17. Even though the search held to be unconstitutional in Kyllo involved a home, the U.S. Supreme Court indicated that the same ruling might apply to a car.

  18. If the U.S. Supreme Court in Caballes holds that a dog sniffing the outside of a car is not a constitutionally protected “search,” this will mean that all dog sniffs are lawful.

  19. Assuming that dog sniffs of cars are held to be constitutional, a defendant will still be able to argue that the evidence found by the dog should be suppressed due to an illegal traffic stop or an unduly prolonged detention.

  20. In considering whether dog sniffs are searches in Caballes, the U.S. Supreme Court will not factor into its decision how important dogs are in ferreting out bombs and thwarting terrorist plots.

Contact Us Site Map Notices Privacy Policy
© 2024 The State Bar of California