UNITED STATES v. ARVIZU

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266 OCTOBER TERM, 2001
Syllabus
UNITED STATES v. ARVIZU
certiorari to the united states court of appeals for
the ninth circuit
No. 00–1519. Argued November 27, 2001—Decided January 15, 2002
Respondent was stopped by Border Patrol Agent Stoddard while driving
on an unpaved road in a remote area of southeastern Arizona. A search
of his vehicle revealed more than 100 pounds of marijuana, and he was
charged with possession with intent to distribute. The Federal District
Court denied respondent’s motion to suppress, citing a number of facts
that gave Stoddard reasonable suspicion to stop the vehicle. The Ninth
Circuit reversed. In its view, fact-specific weighing of circumstances
or other multifactor tests introduced uncertainty and unpredictability
into the Fourth Amendment analysis, making it necessary to clearly
delimit the factors that an officer may consider in making stops such
as this one. It then held that several factors relied upon by the Dis-
trict Court carried little or no weight in the reasonable-suspicion cal-
culus and that the remaining factors were not enough to render the
stop permissible.
Held: Considering the totality of the circumstances and giving due weight
to the factual inferences drawn by Stoddard and the District Court
Judge, Stoddard had reasonable suspicion to believe that respondent
was engaged in illegal activity. Because the “balance between the pub-
lic interest and the individual’s right to personal security,” United States
v. Brignoni-Ponce, 422 U. S. 873, 878, tilts in favor of a standard less
than probable cause in brief investigatory stops of persons or vehicles,
the Fourth Amendment is satisfied if the officer’s action is supported by
reasonable suspicion to believe that criminal activity “may be afoot,”
United States v. Sokolow, 490 U. S. 1, 7. In making reasonable-
suspicion determinations, reviewing courts must look at the “totality
of the circumstances” of each case to see whether the detaining officer
has a “particularized and objective basis” for suspecting legal wrong-
doing. See, e. g., United States v. Cortez, 449 U. S. 411, 417–418. This
process allows officers to draw on their own experiences and specialized
training to make inferences from and deductions about the cumulative
information available. Id., at 418. The Ninth Circuit’s methodology
departs sharply from these teachings, and it reached the wrong result
in this case. Its evaluation and rejection of certain factors in isolation
from each other does not take into account the “totality of the circum-

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Opinion of the Court
stances,” as this Court’s cases have understood that phrase. The court
appeared to believe that each of Stoddard’s observations that was by
itself susceptible to an innocent explanation was entitled to no weight.
Terry v. Ohio, 392 U. S. 1, however, precludes this sort of divide-and-
conquer analysis. And the court’s view that it was necessary to clearly
delimit an officer’s consideration of certain factors to reduce troubling
uncertainty also runs counter to this Court’s cases and underestimates
the reasonable-suspicion standard’s usefulness in guiding officers in
the field. The de novo standard for appellate review of reasonable-
suspicion determinations has, inter alia, a tendency to unify precedent
and a capacity to provide law enforcement officers the tools to reach the
correct decision beforehand. Ornelas v. United States, 517 U. S. 690,
691, 697–698. The Ninth Circuit’s approach would seriously undermine
the “totality of the circumstances” principle governing the existence
vel non of “reasonable suspicion.” Here, it was reasonable for Stod-
dard to infer from his observations, his vehicle registration check,
and his border patrol experience that respondent had set out on a route
used by drug smugglers and that he intended to pass through the area
during a border patrol shift change; and Stoddard’s assessment of the
reactions of respondent and his passengers was entitled to some weight.
Although each of the factors alone is susceptible to innocent explanation,
and some factors are more probative than others, taken together, they
sufficed to form a particularized and objective basis for stopping the
vehicle. Pp. 273–278.
232 F. 3d 1241, reversed and remanded.
Rehnquist, C. J., delivered the opinion for a unanimous Court.
Scalia, J., filed a concurring opinion, post, p. 278.
Austin C. Schlick argued the cause for the United States.
With him on the briefs were Solicitor General Olson, Assist-
ant Attorney General Chertoff, Deputy Solicitor General
Dreeben, and Deborah Watson.
Victoria A. Brambl argued the cause for respondent.
With her on the brief was Fredric F. Kay.*
*Briefs of amici curiae urging affirmance were filed for the DKT Lib-
erty Project by Julia M. Carpenter; and for the National Association
of Criminal Defense Lawyers et al. by Lawrence S. Lustberg and Risa
E. Kaufman.

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268 UNITED STATES v. ARVIZU
Opinion of the Court
Chief Justice Rehnquist delivered the opinion of the
Court.
Respondent Ralph Arvizu was stopped by a border patrol
agent while driving on an unpaved road in a remote area
of southeastern Arizona. A search of his vehicle turned up
more than 100 pounds of marijuana. The District Court for
the District of Arizona denied respondent’s motion to sup-
press, but the Court of Appeals for the Ninth Circuit re-
versed. In the course of its opinion, it categorized certain
factors relied upon by the District Court as simply out of
bounds in deciding whether there was “reasonable suspicion”
for the stop. We hold that the Court of Appeals’ methodol-
ogy was contrary to our prior decisions and that it reached
the wrong result in this case.
On an afternoon in January 1998, Agent Clinton Stoddard
was working at a border patrol checkpoint along U. S. High-
way 191 approximately 30 miles north of Douglas, Arizona.
App. 22, 24. See Appendix, infra (containing a map of the
area noting the location of the checkpoint and other points
important to this case). Douglas has a population of about
13,000 and is situated on the United States-Mexico border
in the southeastern part of the State. Only two highways
lead north from Douglas. See App. 157. Highway 191
leads north to Interstate 10, which passes through Tucson
and Phoenix. State Highway 80 heads northeast through
less populated areas toward New Mexico, skirting south and
east of the portion of the Coronado National Forest that lies
approximately 20 miles northeast of Douglas.1
The checkpoint is located at the intersection of 191 and
Rucker Canyon Road, an unpaved east-west road that con-
nects 191 and the Coronado National Forest. When the
checkpoint is operational, border patrol agents stop the traf-
1 Coronado National Forest consists of 12 widely scattered sections of
land covering 1,780,000 acres in southeastern Arizona and southwestern
New Mexico. The section of the forest near Douglas includes the Chirica-
hua, Dragoon, and Peloncillo Mountain Ranges.

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fic on 191 as part of a coordinated effort to stem the flow of
illegal immigration and smuggling across the international
border. See id., at 20–21. Agents use roving patrols to
apprehend smugglers trying to circumvent the checkpoint
by taking the backroads, including those roads through the
sparsely populated area between Douglas and the national
forest. Id., at 21–22, 26, 80. Magnetic sensors, or “intru-
sion devices,” facilitate agents’ efforts in patrolling these
areas. See id., at 25. Directionally sensitive, the sensors
signal the passage of traffic that would be consistent with
smuggling activities. Ibid.; Tr. of Oral Arg. 23–24.
Sensors are located along the only other northbound road
from Douglas besides Highways 191 and 80: Leslie Canyon
Road. Leslie Canyon Road runs roughly parallel to 191,
about halfway between 191 and the border of the Coronado
National Forest, and ends when it intersects Rucker Canyon
Road. It is unpaved beyond the 10-mile stretch leading
out of Douglas and is very rarely traveled except for use
by local ranchers and forest service personnel. App. 26.
Smugglers commonly try to avoid the 191 checkpoint by
heading west on Rucker Canyon Road from Leslie Canyon
Road and thence to Kuykendall Cutoff Road, a primitive dirt
road that leads north approximately 12 miles east of 191.
Id., at 29–30. From there, they can gain access to Tucson
and Phoenix. Id., at 30.
Around 2:15 p.m., Stoddard received a report via Douglas
radio that a Leslie Canyon Road sensor had been triggered.
Id., at 24. This was significant to Stoddard for two reasons.
First, it suggested to him that a vehicle might be trying
to circumvent the checkpoint. Id., at 27. Second, the
timing coincided with the point when agents begin heading
back to the checkpoint for a shift change, which leaves the
area unpatrolled. Id., at 26, 47. Stoddard knew that alien
smugglers did extensive scouting and seemed to be most
active when agents were en route back to the checkpoint.
Another border patrol agent told Stoddard that the same

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sensor had gone off several weeks before and that he had
apprehended a minivan using the same route and witnessed
the occupants throwing bundles of marijuana out the door.
Id., at 27.
Stoddard drove eastbound on Rucker Canyon Road to
investigate. As he did so, he received another radio report
of sensor activity. Id., at 29. It indicated that the vehicle
that had triggered the first sensor was heading westbound
on Rucker Canyon Road. He continued east, passing Kuy-
kendall Cutoff Road. He saw the dust trail of an approach-
ing vehicle about a half mile away. Id., at 31. Stoddard
had not seen any other vehicles and, based on the timing,
believed that this was the one that had tripped the sensors.
Id., at 31–32. He pulled off to the side of the road at a slight
slant so he could get a good look at the oncoming vehicle as
it passed by. Id., at 32.
It was a minivan, a type of automobile that Stoddard knew
smugglers used. Id., at 33. As it approached, it slowed
dramatically, from about 50–55 to 25–30 miles per hour. Id.,
at 32, 57. He saw five occupants inside. An adult man was
driving, an adult woman sat in the front passenger seat, and
three children were in the back. Id., at 33–34. The driver
appeared stiff and his posture very rigid. He did not look
at Stoddard and seemed to be trying to pretend that Stod-
dard was not there. Id., at 33. Stoddard thought this sus-
picious because in his experience on patrol most persons look
over and see what is going on, and in that area most drivers
give border patrol agents a friendly wave. Id., at 59. Stod-
dard noticed that the knees of the two children sitting in the
very back seat were unusually high, as if their feet were
propped up on some cargo on the floor. Id., at 34.
At that point, Stoddard decided to get a closer look, so he
began to follow the vehicle as it continued westbound on
Rucker Canyon Road toward Kuykendall Cutoff Road. Id.,
at 34–35. Shortly thereafter, all of the children, though

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still facing forward, put their hands up at the same time and
began to wave at Stoddard in an abnormal pattern. Id., at
35, 61. It looked to Stoddard as if the children were being
instructed. Their odd waving continued on and off for about
four to five minutes. Id., at 35, 73.
Several hundred feet before the Kuykendall Cutoff Road
intersection, the driver signaled that he would turn. Id.,
at 36. At one point, the driver turned the signal off, but
just as he approached the intersection he put it back on and
abruptly turned north onto Kuykendall. The turn was sig-
nificant to Stoddard because it was made at the last place
that would have allowed the minivan to avoid the checkpoint.
Id., at 37. Also, Kuykendall, though passable by a sedan or
van, is rougher than either Rucker Canyon or Leslie Canyon
Roads, and the normal traffic is four-wheel-drive vehicles.
Id., at 36, 63–64. Stoddard did not recognize the minivan
as part of the local traffic agents encounter on patrol, id.,
at 37, and he did not think it likely that the minivan was
going to or coming from a picnic outing. He was not aware
of any picnic grounds on Turkey Creek, which could be
reached by following Kuykendall Cutoff all the way up. Id.,
at 54. He knew of picnic grounds and a Boy Scout camp
east of the intersection of Rucker Canyon and Leslie Canyon
Roads, id., at 31, 53, 54, but the minivan had turned west at
that intersection. And he had never seen anyone picnicking
or sightseeing near where the first sensor went off. Id., at
53, 75.
Stoddard radioed for a registration check and learned
that the minivan was registered to an address in Douglas
that was four blocks north of the border in an area notorious
for alien and narcotics smuggling. Id., at 37–38, 66–67.
After receiving the information, Stoddard decided to make a
vehicle stop. Id., at 38. He approached the driver and
learned that his name was Ralph Arvizu. Stoddard asked
if respondent would mind if he looked inside and searched

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the vehicle. Id., at 43. Respondent agreed, and Stoddard
discovered marijuana in a black duffel bag under the feet of
the two children in the back seat. Id., at 45–46. Another
bag containing marijuana was behind the rear seat. Id.,
at 46. In all, the van contained 128.85 pounds of marijuana,
worth an estimated $99,080. Brief for United States 8.
Respondent was charged with possession with intent to
distribute marijuana in violation of 21 U. S. C. § 841(a)(1)
(1994 ed.). He moved to suppress the marijuana, arguing
among other things that Stoddard did not have reasonable
suspicion to stop the vehicle as required by the Fourth
Amendment. After holding a hearing where Stoddard and
respondent testified, the District Court for the District
of Arizona ruled otherwise. App. to Pet. for Cert. 21a. It
pointed to a number of the facts described above and noted
particularly that any recreational areas north of Rucker Can-
yon would have been accessible from Douglas via 191 and
another paved road, making it unnecessary to take a 40-to-
50-mile trip on dirt roads. Id., at 22a.
The Court of Appeals for the Ninth Circuit reversed. 232
F. 3d 1241 (2000). In its view, fact-specific weighing of cir-
cumstances or other multifactor tests introduced “a trou-
bling degree of uncertainty and unpredictability” into the
Fourth Amendment analysis. Id., at 1248 (internal quo-
tation marks omitted). It therefore “attempt[ed] . . . to
describe and clearly delimit the extent to which certain fac-
tors may be considered by law enforcement officers in mak-
ing stops such as the stop involv[ing]” respondent. Ibid.
After characterizing the District Court’s analysis as rely-
ing on a list of 10 factors, the Court of Appeals proceeded
to examine each in turn. It held that seven of the factors,
including respondent’s slowing down, his failure to acknowl-
edge Stoddard, the raised position of the children’s knees,
and their odd waving carried little or no weight in the
reasonable-suspicion calculus. The remaining factors—the

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road’s use by smugglers, the temporal proximity between
respondent’s trip and the agents’ shift change, and the use
of minivans by smugglers—were not enough to render the
stop permissible. Id., at 1251. We granted certiorari to
review the decision of the Court of Appeals because of
its importance to the enforcement of federal drug and immi-
gration laws. 532 U. S. 1065 (2001).
The Fourth Amendment prohibits “unreasonable searches
and seizures” by the Government, and its protections extend
to brief investigatory stops of persons or vehicles that
fall short of traditional arrest. Terry v. Ohio, 392 U. S.
1, 9 (1968); United States v. Cortez, 449 U. S. 411, 417 (1981).
Because the “balance between the public interest and the
individual’s right to personal security,” United States v.
Brignoni-Ponce, 422 U. S. 873, 878 (1975), tilts in favor of a
standard less than probable cause in such cases, the Fourth
Amendment is satisfied if the officer’s action is supported by
reasonable suspicion to believe that criminal activity “ ‘may
be afoot,’ ” United States v. Sokolow, 490 U. S. 1, 7 (1989)
(quoting Terry, supra, at 30). See also Cortez, 449 U. S., at
417 (“An investigatory stop must be justified by some objec-
tive manifestation that the person stopped is, or is about to
be, engaged in criminal activity”).
When discussing how reviewing courts should make
reasonable-suspicion determinations, we have said repeat-
edly that they must look at the “totality of the circum-
stances” of each case to see whether the detaining officer has
a “particularized and objective basis” for suspecting legal
wrongdoing. See, e. g., id., at 417–418. This process allows
officers to draw on their own experience and specialized
training to make inferences from and deductions about the
cumulative information available to them that “might well
elude an untrained person.” Id., at 418. See also Ornelas
v. United States, 517 U. S. 690, 699 (1996) (reviewing court
must give “due weight” to factual inferences drawn by resi-

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dent judges and local law enforcement officers). Although
an officer’s reliance on a mere “ ‘hunch’ ” is insufficient to
justify a stop, Terry, supra, at 27, the likelihood of crimi-
nal activity need not rise to the level required for probable
cause, and it falls considerably short of satisfying a pre-
ponderance of the evidence standard, Sokolow, supra, at 7.
Our cases have recognized that the concept of reasonable
suspicion is somewhat abstract. Ornelas, supra, at 696
(principle of reasonable suspicion is not a “ ‘finely-tuned
standar[d]’ ”); Cortez, supra, at 417 (the cause “sufficient to
authorize police to stop a person” is an “elusive concept”).
But we have deliberately avoided reducing it to “ ‘a neat set
of legal rules,’ ” Ornelas, supra, at 695–696 (quoting Illinois
v. Gates, 462 U. S. 213, 232 (1983)). In Sokolow, for example,
we rejected a holding by the Court of Appeals that distin-
guished between evidence of ongoing criminal behavior and
probabilistic evidence because it “create[d] unnecessary dif-
ficulty in dealing with one of the relatively simple concepts
embodied in the Fourth Amendment.” 490 U. S., at 7–8.
We think that the approach taken by the Court of Appeals
here departs sharply from the teachings of these cases. The
court’s evaluation and rejection of seven of the listed factors
in isolation from each other does not take into account the
“totality of the circumstances,” as our cases have understood
that phrase. The court appeared to believe that each obser-
vation by Stoddard that was by itself readily susceptible to
an innocent explanation was entitled to “no weight.” See
232 F. 3d, at 1249–1251. Terry, however, precludes this sort
of divide-and-conquer analysis. The officer in Terry ob-
served the petitioner and his companions repeatedly walk
back and forth, look into a store window, and confer with one
another. Although each of the series of acts was “perhaps
innocent in itself,” we held that, taken together, they “war-
ranted further investigation.” 392 U. S., at 22. See also
Sokolow, supra, at 9 (holding that factors which by them-

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selves were “quite consistent with innocent travel” collec-
tively amounted to reasonable suspicion).
The Court of Appeals’ view that it was necessary to
“clearly delimit” an officer’s consideration of certain fac-
tors to reduce “troubling . . . uncertainty,” 232 F. 3d, at
1248, also runs counter to our cases and underestimates
the usefulness of the reasonable-suspicion standard in guid-
ing officers in the field. In Ornelas v. United States, we
held that the standard for appellate review of reasonable-
suspicion determinations should be de novo, rather than for
“abuse of discretion.” 517 U. S., at 691. There, we rea-
soned that de novo review would prevent the affirmance
of opposite decisions on identical facts from different judi-
cial districts in the same circuit, which would have been pos-
sible under the latter standard, and would allow appellate
courts to clarify the legal principles. Id., at 697. Other
benefits of the approach, we said, were its tendency to unify
precedent and greater capacity to provide law enforcement
officers with the tools to reach correct determinations be-
forehand: Even if in many instances the factual “mosaic”
analyzed for a reasonable-suspicion determination would
preclude one case from squarely controlling another, “two
decisions when viewed together may usefully add to the
body of law on the subject.” Id., at 697–698.
But the Court of Appeals’ approach would go considerably
beyond the reasoning of Ornelas and seriously undercut the
“totality of the circumstances” principle which governs the
existence vel non of “reasonable suspicion.” Take, for ex-
ample, the court’s positions that respondent’s deceleration
could not be considered because “slowing down after spot-
ting a law enforcement vehicle is an entirely normal response
that is in no way indicative of criminal activity” and that
his failure to acknowledge Stoddard’s presence provided no
support because there were “no ‘special circumstances’ ren-
dering ‘innocent avoidance . . . improbable.’ ” 232 F. 3d,
at 1248–1249. We think it quite reasonable that a driver’s

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Opinion of the Court
slowing down, stiffening of posture, and failure to acknowl-
edge a sighted law enforcement officer might well be un-
remarkable in one instance (such as a busy San Francisco
highway) while quite unusual in another (such as a remote
portion of rural southeastern Arizona). Stoddard was en-
titled to make an assessment of the situation in light of his
specialized training and familiarity with the customs of the
area’s inhabitants. See Ornelas, supra, at 699. To the ex-
tent that a totality of the circumstances approach may ren-
der appellate review less circumscribed by precedent than
otherwise, it is the nature of the totality rule.
In another instance, the Court of Appeals chose to dismiss
entirely the children’s waving on grounds that odd conduct
by children was all too common to be probative in a particu-
lar case. See 232 F. 3d, at 1249 (“If every odd act engaged
in by one’s children . . . could contribute to a finding of rea-
sonable suspicion, the vast majority of American parents
might be stopped regularly within a block of their homes”).
Yet this case did not involve simply any odd act by children.
At the suppression hearing, Stoddard testified about the chil-
dren’s waving several times, and the record suggests that
he physically demonstrated it as well.2 The District Court
Judge, who saw and heard Stoddard, then characterized the
waving as “methodical,” “mechanical,” “abnormal,” and “cer-
tainly . . . a fact that is odd and would lead a reasonable
officer to wonder why they are doing this.” App. to Pet. for
Cert. 25a. Though the issue of this case does not turn on
the children’s idiosyncratic actions, the Court of Appeals
should not have casually rejected this factor in light of the
District Court’s superior access to the evidence and the
well-recognized inability of reviewing courts to reconstruct
what happened in the courtroom.
2 At one point during the hearing, Stoddard testified that “[the children’s
waving] wasn’t in a normal pattern. It looked like they were instructed
to do so. They kind of stuck their hands up and began waving to me like
this.” App. 35.

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Opinion of the Court
Having considered the totality of the circumstances and
given due weight to the factual inferences drawn by the law
enforcement officer and District Court Judge, we hold that
Stoddard had reasonable suspicion to believe that respond-
ent was engaged in illegal activity. It was reasonable for
Stoddard to infer from his observations, his registration
check, and his experience as a border patrol agent that re-
spondent had set out from Douglas along a little-traveled
route used by smugglers to avoid the 191 checkpoint. Stod-
dard’s knowledge further supported a commonsense infer-
ence that respondent intended to pass through the area at a
time when officers would be leaving their backroads patrols
to change shifts. The likelihood that respondent and his
family were on a picnic outing was diminished by the fact
that the minivan had turned away from the known recre-
ational areas accessible to the east on Rucker Canyon Road.
Corroborating this inference was the fact that recreational
areas farther to the north would have been easier to reach
by taking 191, as opposed to the 40-to-50-mile trip on un-
paved and primitive roads. The children’s elevated knees
suggested the existence of concealed cargo in the passenger
compartment. Finally, for the reasons we have given, Stod-
dard’s assessment of respondent’s reactions upon seeing him
and the children’s mechanical-like waving, which continued
for a full four to five minutes, were entitled to some weight.
Respondent argues that we must rule in his favor because
the facts suggested a family in a minivan on a holiday outing.
A determination that reasonable suspicion exists, however,
need not rule out the possibility of innocent conduct. See
Illinois v. Wardlow, 528 U. S. 119, 125 (2000) (that flight from
police is not necessarily indicative of ongoing criminal ac-
tivity does not establish Fourth Amendment violation). Un-
doubtedly, each of these factors alone is susceptible of in-
nocent explanation, and some factors are more probative
than others. Taken together, we believe they sufficed to
form a particularized and objective basis for Stoddard’s

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278 UNITED STATES v. ARVIZU
Scalia, J., concurring
stopping the vehicle, making the stop reasonable within the
meaning of the Fourth Amendment.
The judgment of the Court of Appeals is therefore re-
versed, and the case is remanded for further proceedings
consistent with this opinion.
It is so ordered.
[Appendix to opinion of the Court follows this page.]
Justice Scalia, concurring.
I join the opinion of the Court, because I believe it accords
with our opinion in Ornelas v. United States, 517 U. S. 690,
699 (1996), requiring de novo review which nonetheless gives
“due weight to inferences drawn from [the] facts by resident
judges . . . .” As I said in my dissent in Ornelas, however,
I do not see how deferring to the District Court’s factual
inferences (as opposed to its findings of fact) is compatible
with de novo review. Id., at 705.
The Court today says that “due weight” should have been
given to the District Court’s determinations that the chil-
dren’s waving was “ ‘methodical,’ ‘mechanical,’ ‘abnormal,’
and ‘certainly . . . a fact that is odd and would lead a reason-
able officer to wonder why they are doing this.’ ” Ante,
at 276. “Methodical,” “mechanical,” and perhaps even “ab-
normal” and “odd,” are findings of fact that deserve respect.
But the inference that this “would lead a reasonable officer
to wonder why they are doing this,” amounts to the conclu-
sion that their action was suspicious, which I would have
thought (if de novo review is the standard) is the prerogative
of the Court of Appeals. So we have here a peculiar sort of
de novo review.
I may add that, even holding the Ninth Circuit to no more
than the traditional methodology of de novo review, its judg-
ment here would have to be reversed.

Adapted from U. S. Geological Survey Topographic Map of Douglas, Arizona; New Mexico (1959, Revised 1970) Scale 1:250,000.
Border Patrol
checkpoint
Approximate area
where Agent Stoddard
stopped Arvizu’s van
Approximate area where
Arvizu’s van passed Agent
Stoddard’s stationary vehicle
Approximate location
of Border Patrol
sensors
APPENDIX TO OPINION OF THE COURT
LESLIE CANYON RD
LESLIE
CANYON
RD
CANYON
RD
RUCKER CANYON RD
KUYKENDALL

RD
191
191
RUCKER
CUTOFF
191
80
181