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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.
