NOTICE: This opinion is subject to
formal revision before publication in the preliminary print of the
United States Reports. Readers are requested to notify the Reporter
of Decisions, Supreme Court of the United States, Washington,
D. C. 20543, of any typographical or other formal errors, in
order that corrections may be made before the preliminary print
goes to press.
SUPREME COURT OF THE UNITED STATES
_________________
No. 11–817
_________________
FLORIDA, PETITIONER
v. CLAYTON
HARRIS
on writ of certiorari to the supreme court of
florida
[February 19, 2013]
Justice Kagan delivered the opinion of the
Court.
In this case, we consider how a court should
determine if the “alert” of a drug-detection dog during a traffic
stop provides probable cause to search a vehicle. The Florida
Supreme Court held that the State must in every case present an
exhaustive set of records, including a log of the dog’s performance
in the field, to establish the dog’s reliability. See 71 So. 3d
756, 775 (2011). We think that demand inconsistent with the
“flexible, common-sense standard” of probable cause.
Illinois v.
Gates,
462 U.S.
213, 239 (1983).
I
William Wheetley is a K–9 Officer in the
Liberty County, Florida Sheriff’s Office. On June 24, 2006, he was
on a routine patrol with Aldo, a German shepherd trained to detect
certain narcotics (methamphetamine, marijuana, cocaine, heroin, and
ecstasy). Wheetley pulled over respondent Clayton Harris’s truck
because it had an expired license plate. On approaching the
driver’s-side door, Wheetley saw that Harris was “visibly nervous,”
unable to sit still, shaking, and breathing rapidly. Wheetley also
noticed an open can of beer in the truck’s cup holder. App. 62.
Wheetley asked Harris for consent to search the truck, but Harris
refused. At that point, Wheetley retrieved Aldo from the patrol car
and walked him around Harris’s truck for a “free air sniff.”
Id., at 63. Aldo alerted at the driver’s-side door
handle—signaling, through a distinctive set of behaviors, that he
smelled drugs there.
Wheetley concluded, based principally on Aldo’s
alert, that he had probable cause to search the truck. His search
did not turn up any of the drugs Aldo was trained to detect. But it
did reveal 200 loose pseudoephedrine pills, 8,000 matches, a bottle
of hydrochloric acid, two containers of antifreeze, and a coffee
filter full of iodine crystals—all ingredients for making
methamphetamine. Wheetley accordingly arrested Harris, who admitted
after proper
Miranda warnings that he routinely “cooked”
methamphetamine at his house and could not go “more than a few days
without using” it.
Id., at 68. The State charged Harris with
possessing pseudoephedrine for use in manufacturing
methamphetamine.
While out on bail, Harris had another run-in
with Wheetley and Aldo. This time, Wheetley pulled Harris over for
a broken brake light. Aldo again sniffed the truck’s exterior, and
again alerted at the driver’s-side door handle. Wheetley once more
searched the truck, but on this occasion discovered nothing of
interest.
Harris moved to suppress the evidence found in
his truck on the ground that Aldo’s alert had not given Wheetley
probable cause for a search. At the hearing on that motion,
Wheetley testified about both his and Aldo’s training in drug
detection. See
id., at 52–82. In 2004, Wheetley (and a
different dog) completed a 160-hour course in narcotics detection
offered by the Dothan, Alabama Police Department, while Aldo (and a
different handler) completed a similar, 120-hour course given by
the Apopka, Florida Police Department. That same year, Aldo
received a one-year certification from Drug Beat, a private company
that specializes in testing and certifying K–9 dogs. Wheetley and
Aldo teamed up in 2005 and went through another, 40-hour refresher
course in Dothan together. They also did four hours of training
exercises each week to maintain their skills. Wheetley would hide
drugs in certain ve- hicles or buildings while leaving others
“blank” to determine whether Aldo alerted at the right places.
Id., at 57. According to Wheetley, Aldo’s performance in
those exercises was “really good.”
Id., at 60. The State
introduced “Monthly Canine Detection Training Logs” consistent with
that testimony: They showed that Aldo always found hidden drugs and
that he performed “satisfactorily” (the higher of two possible
assessments) on each day of training.
Id., at 109–116.
On cross-examination, Harris’s attorney chose
not to contest the quality of Aldo’s or Wheetley’s training. She
focused instead on Aldo’s certification and his performance in the
field, particularly the two stops of Harris’s truck. Wheetley
conceded that the certification (which, he noted, Florida law did
not require) had expired the year before he pulled Harris over. See
id., at 70–71. Wheetley also acknowledged that he did not
keep complete records of Aldo’s performance in traffic stops or
other field work; instead, he maintained records only of alerts
resulting in arrests. See
id., at 71–72, 74. But Wheetley
defended Aldo’s two alerts to Harris’s seemingly narcotics-free
truck: According to Wheetley, Harris probably transferred the odor
of methamphetamine to the door handle, and Aldo responded to that
“residual odor.”
Id., at 80.
The trial court concluded that Wheetley had
probable cause to search Harris’s truck and so denied the motion to
suppress. Harris then entered a no-contest plea while reserving the
right to appeal the trial court’s ruling. An intermediate state
court summarily affirmed. See 989 So. 2d 1214, 1215 (2008)
(
per curiam).
The Florida Supreme Court reversed, holding that
Wheetley lacked probable cause to search Harris’s vehicle under the
Fourth Amendment. “[W]hen a dog alerts,” the court wrote, “the fact
that the dog has been trained and certified is simply not enough to
establish probable cause.” 71 So. 3d, at 767. To demonstrate a
dog’s reliability, the State needed to produce a wider array of
evidence:
“[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.”
Id., at 775.
The court particularly stressed the need for
“evidence of the dog’s performance history,” including records
showing “how often the dog has alerted in the field without illegal
contraband having been found.”
Id., at 769. That data, the
court stated, could help to expose such problems as a handler’s
tendency (conscious or not) to “cue [a] dog to alert” and “a dog’s
inability to distinguish between resid- ual odors and actual
drugs.”
Id., at 769, 774. Accordingly, an officer like
Wheetley 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.”
Id., at 773.
Judge Canady dissented, maintaining that the
major- ity’s “elaborate and inflexible evidentiary requirements”
went beyond the demands of probable cause.
Id., at 775. He
would have affirmed the trial court’s ruling on the strength of
Aldo’s training history and Harris’s “fail[ure] to present any
evidence challenging” it.
Id., at 776.
We granted certiorari, 566 U. S. ___
(2012), and now reverse.
II
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.
Texas v.
Brown,
460 U.S.
730, 742 (1983) (plurality opinion) (quoting
Carroll v.
United States,
267 U.S.
132, 162 (1925)); see
Safford Unified School Dist. #1 v.
Redding,
557 U.S.
364, 370– 371 (2009). The test for probable cause is not
reducible to “precise definition or quantification.”
Maryland v.
Pringle,
540 U.S.
366, 371 (2003). “Finely tuned standards such as proof beyond a
reasonable doubt or by a preponderance of the evidence . . . have
no place in the [probable-cause] decision.”
Gates, 462
U. S., at 235. All we have required is the kind of “fair
probability” on which “reasonable and prudent [people,] not legal
technicians, act.”
Id., at 238, 231 (internal quotation
marks omitted).
In evaluating whether the State has met this
practical and common-sensical standard, we have consistently looked
to the totality of the circumstances. See,
e.g., Pringle,
540 U. S., at 371;
Gates, 462 U. S., at 232;
Brinegar v.
United States,
338
U.S. 160, 176 (1949). We have rejected rigid rules, bright-line
tests, and mechanistic inquiries in favor of a more flexible,
all-things-considered approach. In
Gates, for example, we
abandoned our old test for assessing the reliability of informants’
tips because it had devolved into a “complex superstructure of
evidentiary and analytical rules,” any one of which, if not
complied with, would derail a finding of probable cause. 462
U. S., at 235. We lamented the development of a list of
“inflexible, independent requirements applicable in every case.”
Id., at 230, n. 6. Probable cause, we emphasized, is “a
fluid concept—turning on the assessment of probabilities in
particular factual contexts—not readily, or even use- fully,
reduced to a neat set of legal rules.”
Id., at 232.
The Florida Supreme Court flouted this
established approach to determining probable cause. To assess the
reliability of a drug-detection dog, the court created a strict
evidentiary checklist, whose every item the State must tick
off.[
1] Most prominently, an
alert cannot establish probable cause under the Florida court’s
decision unless the State introduces comprehensive documentation of
the dog’s prior “hits” and “misses” in the field. (One wonders how
the court would apply its test to a rookie dog.) No matter how much
other proof the State offers of the dog’s reliability, the absent
field performance records will preclude a finding of probable
cause. That is the antithesis of a totality-of-the-circumstances
analysis. It is, indeed, the very thing we criticized in
Gates when we overhauled our method for assessing the
trustworthiness of an informant’s tip. A gap as to any one matter,
we explained, should not sink the State’s case; rather, that
“deficiency . . . may be compensated for, in determining
the overall reliability of a tip, by a strong showing as to
. . . other indicia of reliability.”
Id., at 233.
So too here, a finding of a drug-detection dog’s reliability cannot
depend on the State’s satisfaction of multiple, independent
evidentiary requirements. No more for dogs than for human
informants is such an inflexible checklist the way to prove
reliability, and thus establish probable cause.
Making matters worse, the decision below treats
records of a dog’s field performance as the gold standard in
evidence, when in most cases they have relatively limited import.
Errors may abound in such records. If a dog on patrol fails to
alert to a car containing drugs, the mistake usually will go
undetected because the officer will not initiate a search. Field
data thus may not capture a dog’s false negatives. Conversely (and
more relevant here), if the dog alerts to a car in which the
officer finds no narcotics, the dog may not have made a mistake at
all. The dog may have detected substances that were too well hidden
or present in quantities too small for the officer to locate. Or
the dog may have smelled the residual odor of drugs previously in
the vehicle or on the driver’s person.[
2] Field data thus may markedly overstate a dog’s real
false positives. By contrast, those inaccuracies—in either
direction—do not taint records of a dog’s performance in standard
training and certification settings. There, the designers of an
assessment know where drugs are hidden and where they are not—and
so where a dog should alert and where he should not. The better
measure of a dog’s reliability thus comes away from the field, in
controlled testing environments.[
3]
For that reason, evidence of a dog’s
satisfactory performance in a certification or training program can
itself provide sufficient reason to trust his alert. If a bona fide
organization has certified a dog after testing his reliability in a
controlled setting, a court can presume (subject to any conflicting
evidence offered) that the dog’s alert provides probable cause to
search. The same is true, even in the absence of formal
certification, if the dog has recently and successfully completed a
training program that evaluated his proficiency in locating drugs.
After all, law enforcement units have their own strong incentive to
use effective training and certification programs, because only
accurate drug-detection dogs enable officers to locate contraband
without incurring unnecessary risks or wasting limited time and
resources.
A defendant, however, must have an opportunity
to challenge such evidence of a dog’s reliability, whether by
cross-examining the testifying officer or by introducing his own
fact or expert witnesses. The defendant, for example, may contest
the adequacy of a certification or training program, perhaps
asserting that its standards are too lax or its methods faulty. So
too, the defendant may examine how the dog (or handler) performed
in the assessments made in those settings. Indeed, evidence of the
dog’s (or handler’s) history in the field, although susceptible to
the kind of misinterpretation we have discussed, may sometimes be
relevant, as the Solicitor General acknowledged at oral argument.
See Tr. of Oral Arg. 23–24 (“[T]he defendant can ask the handler,
if the handler is on the stand, about field performance, and then
the court can give that answer whatever weight is appropriate”).
And even assuming a dog is generally reliable, circumstances
surrounding a particular alert may undermine the case for probable
cause—if, say, the officer cued the dog (consciously or not), or if
the team was working under un- familiar conditions.
In short, 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
usual rules of criminal procedure. And the court should then
evaluate the proffered evidence to decide what all the
circumstances demonstrate. If the State has produced proof from
controlled settings that a dog performs reliably in detecting
drugs, and the defendant has not contested that showing, then the
court should find probable cause. If, in contrast, the defendant
has challenged the State’s case (by disputing the reliability of
the dog overall or of a particular alert), then the court should
weigh the competing evidence. 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
reason- ably prudent person think that a search would reveal con-
traband or evidence of a crime. A sniff is up to snuff when it
meets that test.
III
And here, Aldo’s did. The record in this case
amply supported the trial court’s determination that Aldo’s alert
gave Wheetley probable cause to search Harris’s truck.
The State, as earlier described, introduced
substantial evidence of Aldo’s training and his proficiency in
finding drugs. See
supra, at 2–3. The State showed that two
years before alerting to Harris’s truck, Aldo had successfully
completed a 120-hour program in narcotics detection, and separately
obtained a certification from an independent company. And although
the certification expired after a year, the Sheriff’s Office
required continuing training for Aldo and Wheetley. The two
satisfied the requirements of another, 40-hour training program one
year prior to the search at issue. And Wheetley worked with Aldo
for four hours each week on exercises designed to keep their skills
sharp. Wheetley testified, and written records confirmed, that in
those settings Aldo always performed at the highest level.
Harris, as also noted above, declined to
challenge in the trial court any aspect of Aldo’s training. See
supra, at 3. To be sure, Harris’s briefs in
this
Court raise questions about that training’s adequacy—for example,
whether the programs simulated sufficiently diverse environments
and whether they used enough blind testing (in which the handler
does not know the location of drugs and so cannot cue the dog). See
Brief for Respondent 57–58. Similarly, Harris here queries just how
well Aldo performed in controlled testing. See
id., at 58.
But Harris never voiced those doubts in the trial court, and cannot
do so for the first time here. See,
e.g., Rugendorf v.
United States,
376 U.S.
528, 534 (1964). As the case came to the trial court, Aldo had
successfully completed two recent drug-detection courses and
maintained his proficiency through weekly training exercises.
Viewed alone, that training record—with or without the prior
certification—sufficed to establish Aldo’s reliability. See
supra, at 8–9.
And Harris’s cross-examination of Wheetley,
which focused on Aldo’s field performance, failed to rebut the
State’s case. Harris principally contended in the trial court that
because Wheetley did not find any of the substances Aldo was
trained to detect, Aldo’s two alerts must have been false. See
Brief for Respondent 1; App. 77–80. But we have already described
the hazards of inferring too much from the failure of a dog’s alert
to lead to drugs, see
supra, at 7; and here we doubt that
Harris’s logic does justice to Aldo’s skills. Harris cooked and
used methamphetamine on a regular basis; so as Wheetley later
surmised, Aldo likely responded to odors that Harris had
transferred to the driver’s-side door handle of his truck. See
supra, at 3. A well-trained drug-detection dog
should
alert to such odors; his response to them might appear a mistake,
but in fact is not. See n. 2,
supra. And still more
fundamentally, we do not evaluate probable cause in hindsight,
based on what a search does or does not turn up. See
United
States v.
Di Re,
332 U.S.
581, 595 (1948). For the reasons already stated, Wheetley had
good cause to view Aldo as a reliable detector of drugs. And no
special circumstance here gave Wheetley reason to discount Aldo’s
usual dependability or distrust his response to Harris’s truck.
Because training records established Aldo’s
reliability in detecting drugs and Harris failed to undermine that
showing, we agree with the trial court that Wheetley had probable
cause to search Harris’s truck. We accordingly reverse the judgment
of the Florida Supreme Court.
It is so ordered.
