Legal Digest

The Supreme Court Analyzes Major Fourth Amendment Issues in Dog-Sniff Cases

By Richard G. Schott, J.D. 
A police officer escorts a canine officer onto the scene of an incident.

On October 31, 2012, the U.S. Supreme Court heard oral arguments in two separate cases from Florida, each presenting a different constitutional issue involved in law enforcement agencies’ use of drug-sniffing canines. The fact that the Court granted certiorari for both cases in the same term and entertained oral arguments for them on the same day caused some pundits to comment that the Court had “gone to the dogs” or had experienced a “dog-day afternoon.”1 These cases, however, because of the underlying issues involved, were no laughing matter to the law enforcement community.

One of the two cases involved whether probable cause—a bedrock Fourth Amendment concern—existed at the time law enforcement action (the dog sniff) was taken. The second examined whether a search under the Fourth Amendment even had occurred when a drug-sniffing dog alerted to the presence of contraband outside a homeowner’s front door. Clearly, these two cases have the potential to greatly impact how departments employ drug-sniffing canines.  

Florida v. Harris

On February 19, 2013, the U.S. Supreme Court decided the first of the two dog-sniffing cases. In Florida v. Harris, a Liberty County, Florida, Sheriff’s Department K-9 officer on patrol with his German shepherd trained to detect certain narcotics pulled over Clayton Harris because the license plate on his truck had expired.2 When the deputy noticed that Harris was “visibly nervous” (could not sit still and was shaking and breathing rapidly) and had an open can of beer in his truck, he asked for consent to search the vehicle. When Harris refused, the deputy had the German shepherd, Aldo, perform a “free-air sniff” outside the truck. When Aldo gave a positive alert to the presence of drugs, the deputy concluded that he now had probable cause to search the vehicle, even without Harris’ consent.3 Although the search did not reveal any of the drugs Aldo was trained to detect, it produced 200 loose pseudoephedrine pills; 8,000 matches; hydrochloric acid; antifreeze; and a coffee filter full of iodine crystals, all necessary for making methamphetamine. Subsequently, Harris was charged with possessing pseudoephedrine for use in manufacturing methamphetamine.4 Ironically, while Harris was free on bail, the same deputy (again accompanied by his canine partner) pulled Harris over for a traffic violation. Again, Aldo performed a sniff and alerted to the presence of contraband. The deputy again searched Harris’ vehicle based on the alert, but located nothing of evidentiary value.5

Special Agent Schott is a legal instructor at the FBI Academy.
Special Agent Schott is a legal instructor at the FBI Academy.

Harris moved to suppress the evidence recovered in the first search on the grounds that the dog alert indicating the presence of narcotics did not provide the deputy with probable cause, which, in turn, had allowed the search. His argument was based not on the quality of training received by Aldo and his handler but on Aldo’s certification and performance in the field—particularly, the two stops of Harris’ “seemingly narcotics-free” truck.6 At the hearing to settle the issue, testimony revealed that Aldo’s certification (which Florida law did not require) had expired the year before the relevant stop involving Harris and that Aldo’s handler did not keep complete records of Aldo’s performance in the field. Rather, only records of alerts resulting in arrests were maintained.   

After the Florida trial and appellate courts concluded that the dog alert provided probable cause to believe there was evidence in Harris’ truck (which, in turn, allowed the search), the Florida Supreme Court reversed the decision, troubled both by what was and was not presented during the suppression hearing. First, according to Florida’s highest court, “…the fact that a dog has been trained and certified is simply not enough to establish probable cause.”7 Rather, that court mandated a rigid checklist approach to satisfying probable cause in such cases, stating: “[T]he state must present…the dog’s training and certification records, an explanation of the meaning of the particular training and certification, field performance records (including any unverified alerts), and evidence concerning the experience and training of the officer handling the dog, as well as any other objective evidence known to the officer about the dog’s reliability.”8 The Florida high court was especially concerned with the need for “evidence of the dog’s performance history” and “how often the dog has alerted in the field without illegal contraband having been found” because that data could help reveal such problems as a handler’s conscious or unconscious tendency to “cue [a] dog to alert” and a “dog’s inability to distinguish between residual odors and actual drugs.”9 Because of the rigidity of its test, the Florida Supreme Court mandate would dictate that “an officer…who did not keep full records of his dog’s field performance could never have the requisite cause to think ‘that the dog is a reliable indicator of drugs.’”10  

A unanimous U.S. Supreme Court reversed the decision of the Florida Supreme Court. In doing so, the Court relied on its earlier evaluations of the probable cause standard. Justice Elena Kagan, writing for the entire Court, pointed out that “[a] police officer has probable cause to conduct a search when the facts available to him would warrant a person of reasonable caution in the belief that contraband or evidence of a crime is present.”11 She then reiterated that “[t]he test for probable cause is not reducible to ‘precise definition or quantification.’”12 Kagan emphasized that the Court’s prior decisions “rejected rigid rules, bright-line tests, and mechanistic inquiries” in favor of their practical and commonsensical standard based on the totality of the circumstances.13 In rejecting the Florida Supreme Court’s decision, the U.S. Supreme Court pointed out that its Florida counterpart had “flouted this established approach to determining probable cause. To assess the reliability of a drug-detection dog, the Florida court [had] created a strict evidentiary checklist, whose every item the State [would have to] tick off.”14 Based on this approach, the Court wondered how a “rookie dog” ever could satisfy the state court’s test because the absence of any field performance records inevitably would preclude a finding of probable cause.

Based on the U.S. Supreme Court approach, “a probable-cause hearing focusing on a dog’s alert should proceed much like any other. The court should allow the parties to make their best case, consistent with the rules of criminal procedure. And, the court then should evaluate the proffered evidence to decide what all the circumstances demonstrate. In all events, the court should not prescribe, as the Florida Supreme Court did, an inflexible set of evidentiary requirements. The question—similar to every inquiry into probable cause—is whether all the facts surrounding a dog’s alert, viewed through the lens of common sense, would make a reasonably prudent person think that a search would reveal contraband or evidence of a crime.”15 Based on this approach, Justice Kagan concluded that “[a][dog] sniff is up to snuff when it meets that test” and that in this case Aldo’s had.16

An officer enlists a canine officer's help during a traffic stop.

Florida v. Jardines

The more closely watched of the two dog-sniff cases examined by the U.S. Supreme Court during the 2012 term was decided on March 26, 2013. In Florida v. Jardines, the Court addressed whether “using a drug-sniffing dog on a homeowner’s porch to investigate the contents of the home is a ‘search’ within the meaning of the Fourth Amendment.”17

A short recitation of the facts leading up to the legal dispute is important for law enforcement officers who handle drug-sniffing canines. When a detective with the Miami-Dade, Florida, Police Department received an unverified tip that Joelis Jardines was growing marijuana in his home, the department teamed with DEA to investigate. A surveillance team observed Jardines’ home and noted no activity; however, the group could not see inside the residence. A trained canine handler and his drug-sniffing dog (trained to detect marijuana, cocaine, heroin, and several other drugs) approached Jardines’ front porch. While doing so the dog sensed one of the odors he had been trained to detect and began “energetically exploring the area for the strongest point source for that odor.”18 After his exploring, the dog sat down at the base of the front door, indicating it as the strongest source. The dog was on a 6-foot leash during this entire incident. The handler and canine then left the scene after the handler informed the investigating detective of the positive alert. 

Based mainly on the positive alert to the presence of narcotics, the detective obtained a search warrant and executed it at Jardines’ residence later that same day. The search resulted in the seizure of marijuana plants, and Jardines was charged with trafficking in cannabis. Jardines successfully had the evidence suppressed by the trial court on the basis that the canine investigation was an unreasonable search. After an appellate court reversed the suppression, the Florida Supreme Court reinstated the order to suppress. The state high court “h[eld] (as relevant here) that the use of the trained narcotics dog to investigate Jardines’ home was a Fourth Amendment search unsupported by probable cause, rendering invalid the warrant based upon information gathered in that search.”19

Before examining its decision, it is important to note that the U.S. Supreme Court limited its review of the case to the question of whether the handler and the dog approaching and being on the front porch to detect drug odors constituted a Fourth Amendment search. It is settled that the action of a dog sniffing certain odors in a place where the animal has a legal right to be does not constitute a search.20 And, of course, the Court dealt with the issue of probable cause being satisfied from a positive alert by a trained dog earlier in the Harris case discussed at length in this article.       

The U.S. Supreme Court began its analysis of the issue with the following reminder: “The Fourth Amendment provides in relevant part that the ‘right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated.’ The Amendment establishes a simple baseline, one that for much of our history formed the exclusive basis for its protections: When ‘the government obtains information by physically intruding on persons, houses, papers, or effects,‘ a “search”’ within the original meaning of the Fourth Amendment’ has ‘undoubtedly occurred.’”21 This rather simple formula for determining whether a search took place had been resurrected by the Court in United States v. Jones just 1 year before Jardines.22

While the Jones case involved government agents placing a tracking device on a vehicle operated by the subject of a drug investigation, Jardines involved a subject’s home—the item at the Fourth Amendment’s “very core” and “first among equals” when it comes to the Amendment’s protected areas.23 The fact that the investigation actually involved the area “immediately surrounding and associated with the home,” or the curtilage, does not change this high level of protection because curtilage is considered “part of the home itself for Fourth Amendment purposes.”24 Because it was clear that the officers involved in the investigation in Jardines entered his curtilage—the front porch being the “classic exemplar” of such—the Court quickly turned to the “question whether it was accomplished through an unlicensed physical intrusion.”25 As physical intrusion in the case was obvious—“it is undisputed that the detectives had all four of their feet and all four of their companion’s planted on the constitutionally protected extension of Jardines’ home,” this issue ultimately boiled down to whether the intrusion was licensed or not.26 

Turning first to what homeowners typically invite people (including “solicitors, hawkers, and peddlers of all kinds”) to do, the Court noted that there typically is an “implicit license [that] permits [a] visitor to approach the home by the front path, knock promptly, wait briefly to be received, and then (absent invitation to linger longer) leave.”27 Writing for a slim majority of five justices, Justice Antonin Scalia even pointed out that Girl Scouts and trick-or-treaters abide by this traditional invitation routinely. Scalia then concluded that “a police officer not armed with a warrant” could do the same as that is “no more than any private citizen might do.”28 However, that is not what happened in the present case.

“Both dog-sniff cases set forth straightforward guidance for canine handlers.”

The introduction of the trained canine and the explicit quest to uncover contraband and evidence changed this from a situation involving a routine invitee to a much more invasive governmental action. The Court contrasted finding “a visitor knocking on the door” with finding “that same visitor exploring the front path with a metal detector or marching his bloodhound into the garden before saying hello and asking permission.” While the former would be invited, the latter would be highly unwelcomed. In fact, it “would inspire most [people] to—well, call the police,” the Court noted.29 While the express or implied license of most homeowners allows people (including law enforcement officers) to enter their porch to knock on their door and briefly wait for a response, the scope of that license is limited and does not allow anyone to linger on that same porch with a trained dog.

Because the Court relied on its rationale articulated in last year’s Jones decision,30 it did not have to address the well-known Katz v. United States31 “reasonable expectation of privacy” formulation to determine whether a search had occurred in Jardines.32 In fact, the Court acknowledged that whether the activity involved here did or did not amount to a Katz-type search was irrelevant precisely because the Katz test “has been added to, not substituted for” the traditional property-based search test recognized again in Jones.33 Justice Scalia pointed out that “[o]ne virtue of the Fourth Amendment’s property-rights baseline is that it keeps easy cases easy. [Because] officers learned what they learned only by physically intruding on Jardines’ property to gather evidence, [that was] enough to establish that a search occurred.”34


Law enforcement officers appreciate easy-to-apply legal principles. Both dog-sniff cases discussed herein set forth straightforward guidance for canine handlers. As Justice Scalia noted in his majority opinion in Jardines, applying the Court’s Fourth Amendment property-rights search test is easy when a drug-sniffing canine is brought onto a homeowner’s curtilage. The U.S. Supreme Court also affirmed a fairly straightforward, common-sense-type test for determining probable cause in its Harris drug-sniffing dog case.

The principles on which these cases were decided are at the very core of the Fourth Amendment—that is, how to determine whether “probable cause” exists and whether a “search” has occurred. Together, these two Florida-generated cases involving law enforcement’s use of drug dogs have given law enforcement officers solid guidance on determining whether they have probable cause and whether their actions will constitute a search for Fourth Amendment purposes. Law enforcement officers will be able to put these principles to use in their daily activities—not just when using canines but in a whole host of other law enforcement activities, as well. 


1 Michael Doyle, “Drug-Sniffing Cases Send Supreme Court to the Dogs,” The Miami Herald, October 26, 2012,; and Dana Milbank, “The Supreme Court’s Dog-Day Afternoon,” The Washington Post, October 31, 2012, 35500075_1_police-dog-justice-elena-kagan-chief-justice

2 568 U.S. ___ (2013).

3 U.S. Const. amend. IV provides that “The right of the people to be secure in their persons, houses, papers, and effects against unreasonable searches and seizures shall not be violated, and no Warrants shall issue but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched and the persons or things to be seized.” The U.S. Supreme Court has concluded that this language dictates that searches conducted without a warrant are per se unreasonable, subject to limited and delineated exceptions. These exceptions include motor vehicle searches (Carroll v. United States, 267 U.S. 132 (1925)) when there is probable cause to believe evidence is contained in a motor vehicle.

4 Supra note 2, at ___, slip op. at 2. 

5 Id.

6 Id. at ___, slip op. at 3.

7 Florida v. Harris, 71 So. 3d 756, 767 (Fla. 2011).  

8 Id. at 775.

9 Id. at 769; and Id. at 769, 774.

10 Supra note 2, at ___, slip op. at 4, quoting Florida v. Harris, n. 7 at 773. 

11 Supra note 2, at ___, slip op. at 5 (internal quotations omitted).

12 Id. at ___, slip op. at 5 (quoting, Maryland v. Pringle, 540 U.S. 366, 371 (2003)).

13 Supra note 2, at ___, slip op. at 5; and Supra note 13, also citing Illinois v. Gates, 462 U.S. 213, 232 (1983).

14 Supra note 2 at ___, slip op. at 5-6.

15 Supra note 2 at ___, slip op. at 9.

16 Id.

17 569 U.S. ___, (2013); and 569 U.S. at ___, slip op. at 1.

18 Id. at ___, slip op. at 2.

19 Id. at ___, slip op. at 3 (parenthetical in original), citing Florida v. Jardines, 73 So. 3d 34 (2011). 

20 United States v. Place, 462 U.S. 696 (1983); Illinois v. Caballes, 543 U.S. 405 (2005).

21 Id. at ___, slip op. at 3 (quoting U.S. v. Jones, 565 U.S. ___, ___ n.3 (2012))(slip op., at 6, n. 3.).

22 U.S. v. Jones, 565 U.S. ___ (2012).

23 Supra note 19 at ___, slip op. at 4.

24 Id. (quoting Oliver v. United States, 466 U.S. 170, 180 (1984)).

25 Supra note 16 at ___, slip op. at 5. In fn. 1 the Court points out that “[a]t oral argument, the State and its amicus the solicitor general argued that Jardines conceded in the lower courts that the officers had a right to be where they were. This misstates the record. Jardines conceded nothing more than the unsurprising proposition that the officers could have lawfully approached his home to knock on the front door in hopes of speaking with him. Of course, that is not what they did.”

26 Supra note 19 at ___, slip op. at 6.

27 Id.

28 Supra note 19 at ___, slip op. at 6-7 (quoting Kentucky v. King, 563 U.S. ___, ___ (2011) (slip op., at 16)).

29 Supra note 19 at ___, slip op. at 7.

30 Supra note 25.

31 389 U.S. 347 (1967).

32 It should be noted, however, that in a concurring opinion written by Justice Kagan and with whom Justices Ginsburg and Sotomayor joined, Justice Kagan concluded that the activity in this case also would have satisfied the Katz “reasonable expectation of privacy” definition of a Fourth Amendment search. On the other hand, Justice Alito, in his dissenting opinion joined by Chief Justice Roberts and Justices Kennedy and Breyer, determined that the activity in this case would not have satisfied the Katz “reasonable expectation of privacy” definition and, therefore, did not constitute a Katz-type search. Justice Alito also opined that the activity did not constitute a trespass and, therefore, was not a search under either search theory.

33 Supra note 19 at ___, slip op. at 9 (quoting United States v. Jones.); 565 U.S. ___, ___, slip op. at 8 (2012) (emphasis in original)).

34 Supra note 19 at ___, slip op. at 9.

“The principles on which these cases were decided are at the very core of the Fourth Amendment….”