Florida v. Harris

(Slip Opinion) OCTOBER TERM, 2012 1

Syllabus

NOTE: Where it is feasible, a syllabus (headnote) will be released, as is

being done in connection with this case, at the time the opinion is issued.

The syllabus constitutes no part of the opinion of the Court but has been

prepared by the Reporter of Decisions for the convenience of the reader.

See United States v. Detroit Timber & Lumber Co., 200 U. S. 321, 337.

SUPREME COURT OF THE UNITED STATES

Syllabus

FLORIDA v. HARRIS

CERTIORARI TO THE SUPREME COURT OF FLORIDA

No. 11–817. Argued October 31, 2012—Decided February 19, 2013

Officer Wheetley pulled over respondent Harris for a routine traffic

stop. Observing Harris’s nervousness and an open beer can, Wheet-

ley sought consent to search Harris’s truck. When Harris refused,

Wheetley executed a sniff test with his trained narcotics dog, Aldo.

The dog alerted at the driver’s-side door handle, leading Wheetley to

conclude that he had probable cause for a search. That search turned

up nothing Aldo was trained to detect, but did reveal pseudoephed-

rine and other ingredients for manufacturing methamphetamine.

Harris was arrested and charged with illegal possession of those in-

gredients. In a subsequent stop while Harris was out on bail, Aldo

again alerted on Harris’s truck but nothing of interest was found. At

a suppression hearing, Wheetley testified about his and Aldo’s exten-

sive training in drug detection. Harris’s attorney did not contest the

quality of that training, focusing instead on Aldo’s certification and

performance in the field, particularly in the two stops of Harris’s

truck. The trial court denied the motion to suppress, but the Florida

Supreme Court reversed. It held that a wide array of evidence was

always necessary to establish probable cause, including field-

performance records showing how many times the dog has falsely

alerted. If an officer like Wheetley failed to keep such records, he

could never have probable cause to think the dog a reliable indicator

of drugs.

Held: Because training and testing records supported Aldo’s reliability

in detecting drugs and Harris failed to undermine that evidence,

Wheetley had probable cause to search Harris’s truck. Pp. 5–11.

(a) In testing whether an officer has probable cause to conduct a

search, all that is required is the kind of “fair probability” on which

“reasonable and prudent [people] act.” Illinois v. Gates, 462 U. S.

213, 235. To evaluate whether the State has met this practical and

2 FLORIDA v. HARRIS

Syllabus

common-sensical standard, this Court has consistently looked to the

totality of the circumstances and rejected rigid rules, bright-line

tests, and mechanistic inquiries. Ibid.

The Florida Supreme Court flouted this established approach by

creating a strict evidentiary checklist to assess a drug-detection dog’s

reliability. Requiring the State to introduce comprehensive docu-

mentation of the dog’s prior hits and misses in the field, and holding

that absent field records will preclude a finding of probable cause no

matter how much other proof the State offers, is the antithesis of a

totality-of-the-circumstances approach. This is made worse by the

State Supreme Court’s treatment of field-performance records as the

evidentiary gold standard when, in fact, such data may not capture a

dog’s false negatives or may markedly overstate a dog’s false posi-

tives. Such inaccuracies do not taint records of a dog’s performance

in standard training and certification settings, making that perfor-

mance a better measure of a dog’s reliability. Field records may

sometimes be relevant, but the court should evaluate all the evi-

dence, and should not prescribe an inflexible set of requirements.

Under the correct approach, a probable-cause hearing focusing on a

dog’s alert should proceed much like any other, with the court allow-

ing the parties to make their best case and evaluating the totality of

the circumstances. If the State has produced proof from controlled

settings that a dog performs reliably in detecting drugs, and the de-

fendant has not contested that showing, the court should find proba-

ble cause. But a defendant 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 may contest training or testing standards as flawed or

too lax, or raise an issue regarding the particular alert. The court

should then consider all the evidence and apply the usual test for

probable cause—whether all the facts surrounding the 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. Pp. 5–9.

(b) The record in this case amply supported the trial court’s deter-

mination that Aldo’s alert gave Wheetley probable cause to search

the truck. The State introduced substantial evidence of Aldo’s train-

ing and his proficiency in finding drugs. Harris declined to challenge

any aspect of that training or testing in the trial court, and the Court

does not consider such arguments when they are presented for this

first time in this Court. Harris principally relied below on Wheetley’s

failure to find any substance that Aldo was trained to detect. That

infers too much from the failure of a particular alert to lead to drugs,

and did not rebut the State’s evidence from recent training and test-

Cite as: 568 U. S. ____ (2013) 3

Syllabus

ing. Pp. 9–11.

71 So. 3d 756, reversed.

KAGAN, J., delivered the opinion for a unanimous Court.

Cite as: 568 U. S. ____ (2013) 1

Opinion of the Court

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, Wash-

ington, 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 relia-

bility. See 71 So. 3d 756, 775 (2011). We think that de-

mand 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 re-

spondent 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.

2 FLORIDA v. HARRIS

Opinion of the Court

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 de-

tect. But it did reveal 200 loose pseudoephedrine pills,

8,000 matches, a bottle of hydrochloric acid, two contain-

ers 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” metham-

phetamine 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 manu-

facturing 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 Wheet-

ley probable cause for a search. At the hearing on that

motion, Wheetley testified about both his and Aldo’s train-

ing in drug detection. See id., at 52–82. In 2004, Wheet-

ley (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

Cite as: 568 U. S. ____ (2013) 3

Opinion of the Court

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 deter-

mine whether Aldo alerted at the right places. Id., at 57.

According to Wheetley, Aldo’s performance in those exer-

cises 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 train-

ing. 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

4 FLORIDA v. HARRIS

Opinion of the Court

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 perfor-

mance 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 reliabil-

ity.” 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.

Cite as: 568 U. S. ____ (2013) 5

Opinion of the Court

II

A police officer has probable cause to conduct a search

when “the facts available to [him] would ‘warrant a [per-

son] 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., Prin-

gle, 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 as-

sessing 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 “inflexi-

ble, 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

6 FLORIDA v. HARRIS

Opinion of the Court

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 estab-

lish 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 eviden-

tiary 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 evi-

——————

1 Bythe time of oral argument in this case, even Harris declined to

defend the idea that the Fourth Amendment compels the State to

produce each item of evidence the Florida Supreme Court enumerated.

See Tr. of Oral Arg. 29–30 (“I don’t believe the Constitution requires

[that list]”). Harris instead argued that the court’s decision, although

“look[ing] rather didactic,” in fact did not impose any such requirement.

Id., at 29; see id., at 31 (“[I]t’s not a specific recipe that can’t be de-

viated from”). But in reading the decision below as establishing a man-

datory checklist, we do no more than take the court at its (oft-repeated)

word. See, e.g., 71 So. 3d 756, 758, 759, 771, 775 (Fla. 2011) (holding

that the State “must” present the itemized evidence).

Cite as: 568 U. S. ____ (2013) 7

Opinion of the Court

dence, 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 mis-

take 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 narcot-

ics, 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 pre-

viously 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 train-

ing 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

——————

2 See U. S. Dept. of Army, Military Working Dog Program 30 (Pam-

phlet 190–12, 1993) (“The odor of a substance may be present in enough

concentration to cause the dog to respond even after the substance has

been removed. Therefore, when a detector dog responds and no drug

or explosive is found, do not assume the dog has made an error”);

S. Bryson, Police Dog Tactics 257 (2d ed. 2000) (“Four skiers toke up in

the parking lot before going up the mountain. Five minutes later a

narcotic detector dog alerts to the car. There is no dope inside. How-

ever, the dog has performed correctly”). The Florida Supreme Court

treated a dog’s response to residual odor as an error, referring to the

“inability to distinguish between [such] odors and actual drugs” as a

“facto[r] that call[s] into question Aldo’s reliability.” 71 So. 3d, at 773–

774; see supra, at 4. But that statement reflects a misunderstanding.

A detection dog recognizes an odor, not a drug, and should alert when-

ever the scent is present, even if the substance is gone (just as a police

officer’s much inferior nose detects the odor of marijuana for some time

after a joint has been smoked). In the usual case, the mere chance that

the substance might no longer be at the location does not matter; a

well-trained dog’s alert establishes a fair probability—all that is re-

quired for probable cause—that either drugs or evidence of a drug

crime (like the precursor chemicals in Harris’s truck) will be found.

8 FLORIDA v. HARRIS

Opinion of the Court

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 perfor-

mance 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 enforce-

ment 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 some-

times be relevant, as the Solicitor General acknowledged

——————

3 See K. Furton, J. Greb, & H. Holness, Florida Int’l Univ., The Scien-

tific Working Group on Dog and Orthogonal Detector Guidelines 1, 61–

62, 66 (2010) (recommending as a “best practice” that a dog’s reliability

should be assessed based on “the results of certification and proficiency

assessments,” because in those “procedure[s] you should know whether

you have a false positive,” unlike in “most operational situations”).

Cite as: 568 U. S. ____ (2013) 9

Opinion of the Court

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 (con-

sciously 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, con-

sistent 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 defend-

ant 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

10 FLORIDA v. HARRIS

Opinion of the Court

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 success-

fully completed a 120-hour program in narcotics detection,

and separately obtained a certification from an independ-

ent company. And although the certification expired after

a year, the Sheriff ’s Office required continuing training

for Aldo and Wheetley. The two satisfied the require-

ments 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 con-

trolled 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 estab-

lish 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 sub-

Cite as: 568 U. S. ____ (2013) 11

Opinion of the Court

stances 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 metham-

phetamine on a regular basis; so as Wheetley later sur-

mised, 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 show-

ing, we agree with the trial court that Wheetley had prob-

able cause to search Harris’s truck. We accordingly

reverse the judgment of the Florida Supreme Court.

It is so ordered.