OCTOBER TERM, 1992

															Syllabus

															MINNESOTA v. DICKERSON

															CERTIORARI TO THE SUPREME COURT OF MINNESOTA No. 91-2019. Argued
March 3, 1993-Decided June 7, 1993

															Based upon respondent's seemingly evasive actions when
approached by police officers and the fact that he had just left a
building known for cocaine traffic, the officers decided to
investigate further and ordered respondent to submit to a patdown
search. The search revealed no weapons, but the officer conducting
it testified that he felt a small lump in respondent's jacket
pocket, believed it to be a lump of crack cocaine upon examining it
with his fingers, and then reached into the pocket and retrieved a
small bag of cocaine. The state trial court denied respondent's
motion to suppress the cocaine, and he was found guilty of
possession of a controlled substance. The Minnesota Court of
Appeals reversed. In affirming, the State Supreme Court held that
both the stop and the frisk of respondent were valid under Terry v. Ohio, 392 U. S. 1, but found the seizure of
the cocaine to be unconstitutional. Refusing to enlarge the
"plain-view" exception to the Fourth Amendment's warrant
requirement, the court appeared to adopt a categorical rule barring
the seizure of any contraband detected by an officer through the
sense of touch during a patdown search. The court further noted
that, even if it recognized such a "plain-feel" exception, the
search in this case would not qualify because it went far beyond
what is permissible under Terry. Held:

															1. The police may seize nonthreatening contraband detected
through the sense of touch during a protective patdown search of
the sort permitted by Terry, so long as the search stays
within the bounds marked by Terry. pp.372-377.

															(a) Terry permits a brief stop of a person whose
suspicious conduct leads an officer to conclude in light of his
experience that criminal activity may be afoot, and a patdown
search of the person for weapons when the officer is justified in
believing that the person may be armed and presently dangerous.
This protective search-permitted without a warrant and on the basis
of reasonable suspicion less than probable cause-is not meant to
discover evidence of crime, but must be strictly limited to that
which is necessary for the discovery of weapons which might be used
to harm the officer or others. If the protective search goes beyond
what is necessary to determine if the suspect is armed, it 367 is no longer valid under Terry and its fruits will be
suppressed. Sibron v. New York, 392 U. S. 40 , 65-66. pp.
372-373.

															(b) In Michigan v. Long, 463 U. S. 1032 , 1050,
the seizure of contraband other than weapons during a lawful Terry search was justified by reference to the Court's cases
under the "plain-view" doctrine. That doctrine-which permits police
to seize an object without a warrant if they are lawfully in a
position to view it, if its incriminating character is immediately
apparent, and if they have a lawful right of access to it-has an
obvious application by analogy to cases in which an officer
discovers contraband through the sense of touch during an otherwise
lawful search. Thus, if an officer lawfully pats down a suspect's
outer clothing and feels an object whose contour or mass makes its
identity immediately apparent, there has been no invasion of the
suspect's privacy beyond that already authorized by the officer's
search for weapons. Cf., e. g., Illinois v. Andreas, 463 U. S. 765 ,
771. If the object is contraband, its warrantless seizure would be
justified by the realization that resort to a neutral magistrate
under such circumstances would be impracticable and would do little
to promote the Fourth Amendment's objectives. Cf., e. g.,
Arizona v. Hicks, 480 U. S. 321 , 326-327.
Pp. 374-377.

															2. Application of the foregoing principles to the facts of this
case demonstrates that the officer who conducted the search was not
acting within the lawful bounds marked by Terry at the time
he gained probable cause to believe that the lump in respondent's
jacket was contraband. Under the State Supreme Court's
interpretation of the record, the officer never thought that the
lump was a weapon, but did not immediately recognize it as cocaine.
Rather, he determined that it was contraband only after he
squeezed, slid, and otherwise manipulated the pocket's contents.
While Terry entitled him to place his hands on respondent's
jacket and to feel the lump in the pocket, his continued
exploration of the pocket after he concluded that it contained no
weapon was unrelated to the sole justification for the search under Terry. Because this further search was constitutionally
invalid, the seizure of the cocaine that followed is likewise
unconstitutional. Pp. 377-379.

															481 N. W. 2d 840, affirmed.

															WHITE, J., delivered the opinion for a unanimous Court with
respect to Parts I and II, and the opinion of the Court with
respect to Parts III and IV, in which STEVENS, O'CONNOR, SCALIA,
KENNEDY, and SOUTER, JJ., joined. SCALIA, J., filed a concurring
opinion, post, p. 379. REHNQUIST, C. J., filed an opinion
concurring in part and dissenting in part, in which BLACKMUN and
THOMAS, JJ., joined, post, p. 383. 368 Michael O. Freeman argued the cause for
petitioner.

															With him on the briefs were Hubert H. Humphrey III, Attorney General of Minnesota, Patrick C. Diamond, and Beverly J. Wolfe. Richard H. Seamon argued the cause for the United States as
amicus curiae urging reversal. With him on the brief were Solicitor
General Starr, Assistant Attorney General Mueller, Deputy Solicitor
General Bryson, and Kathleen A. Felton.

															Peter W Gorman argued the cause for respondent. With him on the
brief were William R. Kennedy, David H. Knutson, Warren R.
Sagstuen, and Renee J. Bergeron. *

															JUSTICE WHITE delivered the opinion of the Court.

															In this case, we consider whether the Fourth Amendment permits
the seizure of contraband detected through a police officer's sense
of touch during a protective patdown search.

															I

															On the evening of November 9, 1989, two Minneapolis police
officers were patrolling an area on the city's north side in a
marked squad car. At about 8:15 p.m., one of the officers observed
respondent leaving a 12-unit apartment building on Morgan Avenue
North. The officer, having previously responded to complaints of
drug sales in the building's hallways and having executed several
search warrants on the premises, considered the building to be a
notorious "crack house." According to testimony credited by the
trial court, respondent began walking toward the police but, upon
spot-

															* Fred E. Inbau, Wayne W Schmidt, James P. Manak, and Robert
H. Macy filed a brief for Americans for Effective Law
Enforcement, Inc., et al. urging reversal.

															Briefs of amici curiae urging affirmance were filed for
the American Civil Liberties Union et al. by John F. Savarese, Steven R. Shapiro, and Deborah Gilman; and
for the National Association of Criminal Defense Lawyers by David M. Eldridge. 369 ting the squad car and making eye contact with one of the
officers, abruptly halted and began walking in the opposite
direction. His suspicion aroused, this officer watched as
respondent turned and entered an alley on the other side of the
apartment building. Based upon respondent's seemingly evasive
actions and the fact that he had just left a building known for
cocaine traffic, the officers decided to stop respondent and
investigate further.

															The officers pulled their squad car into the alley and ordered
respondent to stop and submit to a patdown search. The search
revealed no weapons, but the officer conducting the search did take
an interest in a small lump in respondent's nylon jacket. The
officer later testified: "[A]s I pat-searched the front of his body, I felt a lump, a
small lump, in the front pocket. I examined it with my fingers and
it slid and it felt to be a lump of crack cocaine in cellophane."
Tr. 9 (Feb. 20, 1990). The officer then reached into respondent's pocket and retrieved
a small plastic bag containing one fifth of one gram of crack
cocaine. Respondent was arrested and charged in Hennepin County
District Court with possession of a controlled substance.

															Before trial, respondent moved to suppress the cocaine.

															The trial court first concluded that the officers were justified
under Terry v. Ohio, 392 U. S. 1 (1968), in
stopping respondent to investigate whether he might be engaged in
criminal activity. The court further found that the officers were
justified in frisking respondent to ensure that he was not carrying
a weapon. Finally, analogizing to the "plain-view" doctrine, under
which officers may make a warrantless seizure of contraband found
in plain view during a lawful search for other items, the trial
court ruled that the officers' seizure of the cocaine did not
violate the Fourth Amendment: "To this Court there is no distinction as to which sensory
perception the officer uses to conclude that the ma- 370 terial is contraband. An experienced officer may rely upon his
sense of smell in DWI stops or in recognizing the smell of burning
marijuana in an automobile. The sound of a shotgun being racked
would clearly support certain reactions by an officer. The sense of
touch, grounded in experience and training, is as reliable as
perceptions drawn from other senses. 'Plain feel,' therefore, is no
different than plain view and will equally support the seizure
here." App. to Pet. for Cert. C-5. His suppression motion having failed, respondent proceeded to
trial and was found guilty.

															On appeal, the Minnesota Court of Appeals reversed.

															The court agreed with the trial court that the investigative
stop and protective patdown search of respondent were lawful under Terry because the officers had a reasonable belief based on
specific and articulable facts that respondent was engaged in
criminal behavior and that he might be armed and dangerous. The
court concluded, however, that the officers had overstepped the
bounds allowed by Terry in seizing the cocaine. In doing so,
the Court of Appeals "decline[d] to adopt the plain feel exception"
to the warrant requirement. 469 N. W. 2d 462, 466 (1991).

															The Minnesota Supreme Court affirmed. Like the Court of Appeals,
the State Supreme Court held that both the stop and the frisk of
respondent were valid under Terry, but found the seizure of
the cocaine to be unconstitutional. The court expressly refused "to
extend the plain view doctrine to the sense of touch" on the
grounds that "the sense of touch is inherently less immediate and
less reliable than the sense of sight" and that "the sense of touch
is far more intrusive into the personal privacy that is at the core
of the [F]ourth [A]mendment." 481 N. W. 2d 840, 845 (1992). The
court thus appeared to adopt a categorical rule barring the seizure
of any contraband detected by an officer through the sense of touch
during a patdown search for weapons. The court further noted that
"[e]ven if we recognized a 'plain feel' ex- 371 ception, the search in this case would not qualify" because
"[t]he pat search of the defendant went far beyond what is
permissible under Terry." Id., at 843, 844, n. 1. As the
State Supreme Court read the record, the officer conducting the
search ascertained that the lump in respondent's jacket was
contraband only after probing and investigating what he certainly
knew was not a weapon. See id., at 844.

															We granted certiorari, 506 U. S. 814 (1992), to resolve a
conflict among the state and federal courts over whether contraband
detected through the sense of touch during a patdown search may be
admitted into evidence.1 We now affirm.2

															1 Most state and federal courts have recognized a so-called
"plain-feel" or "plain-touch" corollary to the plain-view doctrine.
See United States v. Coleman, 969
F.2d 126 , 132 (CA5 1992); United States v. Salazar, 945 F. 2d 47, 51 (CA2 1991), cert. denied,
504 U. S. 923 (1992); United States v. Buchannon, 878 F.2d
1065 , 1067 (CA8 1989); United States v. Williams, 262 U. S. App. D. C. 112, 119-124, 822 F.2d
1174 , 1181-1186 (1987); United States v. Norman, 701 F.2d
295 , 297 (CA4), cert. denied, 464 U. S. 820 (1983);
People v. Chavers, 33 Cal. 3d 462, 471-473, 658 P. 2d
96, 102-104 (1983); Dickerson v. State, No. 228, 1993
Del. LEXIS 12, *3-*4 (Jan. 26, 1993); State v. Guy, 172 Wis. 2d 86, 101-102,492 N. W. 2d 311, 317-318 (1992). Some
state courts, however, like the Minnesota court in this case, have
rejected such a corollary. See People v. Diaz, 81 N.
Y. 2d 106, 612 N. E. 2d 298 (1993); State v. Collins, 139 Ariz. 434, 435-438, 679 P. 2d 80, 81-84 (Ct. App. 1983); People v. McCarty, 11 Ill. App. 3d 421, 422, 296 N.
E. 2d 862, 863 (1973); State v. Rhodes, 788 P. 2d
1380, 1381 (Okla. Crim. App. 1990); State v. Broadnax, 98 Wash. 2d 289, 296-301, 654 P. 2d 96, 101-103
(1982); cf. Commonwealth v. Marconi, 408 Pa. Super.
601, 611-615, and n. 17,597 A. 2d 616, 621-623, and n. 17 (1991),
appeal denied, 531 Pa. 638, 611 A. 2d 711 (1992).

															2 Before reaching the merits of the Fourth Amendment issue, we
must address respondent's contention that the case is moot. After
respondent was found guilty of the drug possession charge, the
trial court sentenced respondent under a diversionary sentencing
statute to a 2-year period of probation. As allowed by the
diversionary scheme, no judgment of conviction was entered and,
upon respondent's successful completion of probation, the original
charges were dismissed. See Minn. Stat. § 152.18 (1992). Respondent
argues that the case has been rendered moot by the dismissal of the
original criminal charges. We often have observed, however,
that 372 II A

															The Fourth Amendment, made applicable to the States by way of
the Fourteenth Amendment, Mapp v. Ohio, 367 U. S. 643 (1961),
guarantees "[t]he right of the people to be secure in their
persons, houses, papers, and effects, against unreasonable searches
and seizures." Time and again, this Court has observed that
searches and seizures" 'conducted outside the judicial process,
without prior approval by judge or magistrate, are per se unreasonable under the Fourth Amendment-subject only to a few
specifically established and well delineated exceptions.'" Thompson v. Louisiana, 469 U. S. 17 , 19-20 (1984) (per curiam) (quoting Katz v. United States, 389 U. S. 347 ,
357 (1967) (footnotes omitted)); Mincey v. Arizona, 437 U. S. 385 ,
390 (1978); see also United States v. Place, 462 U. S. 696 , 701
(1983). One such exception was

															"the possibility of a criminal defendant's suffering 'collateral
legal consequences' from a sentence already served" precludes a
finding of mootness. Pennsylvania v. Mimms, 434 U. S. 106 , 108, n. 3
(1977) (per curiam); see also Evitts v. Lucey, 469 U. S. 387 ,
391, n. 4 (1985); Sibron v. New York, 392 U. S. 40 , 53-58
(1968). In this case, Minnesota law provides that the proceeding
which culminated in finding respondent guilty "shall not be deemed
a conviction for purposes of disqualifications or disabilities
imposed by law upon conviction of a crime or for any other
purpose." Minn. Stat. § 152.18 (1992). The statute also provides,
however, that a nonpublic record of the charges dismissed pursuant
to the statute "shall be retained by the department of public
safety for the purpose of use by the courts in determining the
merits of subsequent proceedings" against the respondent. Ibid. Construing this provision, the Minnesota Supreme Court
has held that "[t]he statute contemplates use of the record should
[a] defendant have 'future difficulties with the law.''' State v. Goodrich, 256 N. W. 2d 506, 512 (1977).
Moreover, the Court of Appeals for the Eighth Circuit has held that
a diversionary disposition under § 152.18 may be included in
calculating a defendant's criminal history category in the event of
a subsequent federal conviction. United States v. Frank, 932 F.2d
700 , 701 (1991). Thus, we must conclude that reinstatement of
the record of the charges against respondent would carry collateral
legal consequences and that, therefore, a live controversy
remains. 373 recognized in Terry v. Ohio, 392 U. S. 1 (1968), which
held that "where a police officer observes unusual conduct which
leads him reasonably to conclude in light of his experience that
criminal activity may be afoot ... ," the officer may briefly stop
the suspicious person and make "reasonable inquiries" aimed at
confirming or dispelling his suspicions. Id., at 30; see
also Adams v. Williams, 407 U. S. 143 , 145146
(1972). Terry further held that "[w]hen an officer is justified
in believing that the individual whose suspicious behavior he is
investigating at close range is armed and presently dangerous to
the officer or to others," the officer may conduct a patdown search
"to determine whether the person is in fact carrying a weapon." 392
U. S., at 24. "The purpose of this limited search is not to
discover evidence of crime, but to allow the officer to pursue his
investigation without fear of violence .... " Adams, supra, at 146. Rather, a protective search-permitted without a warrant and
on the basis of reasonable suspicion less than probable cause-must
be strictly "limited to that which is necessary for the discovery
of weapons which might be used to harm the officer or others
nearby." Terry, supra, at 26; see also Michigan v. Long, 463 U.
S. 1032 , 1049, and 1052, n. 16 (1983); Ybarra v. Illinois, 444
U. S. 85 , 93-94 (1979). If the protective search goes beyond
what is necessary to determine if the suspect is armed, it is no
longer valid under Terry and its fruits will be suppressed. Sibron v. New York, 392 U. S. 40 , 65-66
(1968).

															These principles were settled 25 years ago when, on the same
day, the Court announced its decisions in Terry and Sibron. The question presented today is whether police
officers may seize nonthreatening contraband detected during a
protective patdown search of the sort permitted by Terry. We
think the answer is clearly that they may, so long as the officers'
search stays within the bounds marked by Terry. 374 B

															We have already held that police officers, at least under
certain circumstances, may seize contraband detected during the
lawful execution of a Terry search. In Michigan v. Long, supra, for example, police approached a man who had
driven his car into a ditch and who appeared to be under the
influence of some intoxicant. As the man moved to reenter the car
from the roadside, police spotted a knife on the floorboard. The
officers stopped the man, subjected him to a patdown search, and
then inspected the interior of the vehicle for other weapons.
During the search of the passenger compartment, the police
discovered an open pouch containing marijuana and seized it. This
Court upheld the validity of the search and seizure under Terry. The Court held first that, in the context of a
roadside encounter, where police have reasonable suspicion based on
specific and articulable facts to believe that a driver may be
armed and dangerous, they may conduct a protective search for
weapons not only of the driver's person but also of the passenger
compartment of the automobile. 463 U. S., at 1049. Of course, the
protective search of the vehicle, being justified solely by the
danger that weapons stored there could be used against the officers
or bystanders, must be "limited to those areas in which a weapon
may be placed or hidden." Ibid. The Court then held: "If,
while conducting a legitimate Terry search of the interior
of the automobile, the officer should, as here, discover contraband
other than weapons, he clearly cannot be required to ignore the
contraband, and the Fourth Amendment does not require its
suppression in such circumstances." Id., at 1050; accord, Sibron, 392 U. S., at 69-70 (WHITE, J., concurring); id., at
79 (Harlan, J., concurring in result).

															The Court in Long justified this latter holding by
reference to our cases under the "plain-view" doctrine. See Long, supra, at 1050; see also United States v. Hensley, 469 U. S. 221, 235 (1985) (upholding plain-view
seizure in context 375 of Terry stop). Under that doctrine, if police are
lawfully in a position from which they view an object, if its
incriminating character is immediately apparent, and if the
officers have a lawful right of access to the object, they may
seize it without a warrant. See Horton v. California, 496 U. S. 128 ,
136-137 (1990); Texas v. Brown, 460 U. S. 730 , 739 (1983)
(plurality opinion). If, however, the police lack probable cause to
believe that an object in plain view is contraband without
conducting some further search of the object-i. e., if "its
incriminating character [is not] 'immediately apparent,'" Horton, supra, at 136-the plain-view doctrine cannot justify
its seizure. Arizona v. Hicks, 480 U. S. 321 (1987).

															We think that this doctrine has an obvious application by
analogy to cases in which an officer discovers contraband through
the sense of touch during an otherwise lawful search. The rationale
of the plain-view doctrine is that if contraband is left in open
view and is observed by a police officer from a lawful vantage
point, there has been no invasion of a legitimate expectation of
privacy and thus no "search" within the meaning of the Fourth
Amendment-or at least no search independent of the initial
intrusion that gave the officers their vantage point. See Illinois v. Andreas, 463 U. S. 765 , 771
(1983); Texas v. Brown, supra, at 740. The
warrantless seizure of contraband that presents itself in this
manner is deemed justified by the realization that resort to a
neutral magistrate under such circumstances would often be
impracticable and would do little to promote the objectives of the
Fourth Amendment. See Hicks, supra, at 326-327; Coolidge v. New Hampshire, 403 U. S. 443 , 467468,
469-470 (1971) (opinion of Stewart, J.). The same can be said of
tactile discoveries of contraband. If a police officer lawfully
pats down a suspect's outer clothing and feels an object whose
contour or mass makes its identity immediately apparent, there has
been no invasion of the suspect's privacy beyond that already
authorized by the officer's search for weapons; if the object is
contraband, its warrantless seizure 376 would be justified by the same practical considerations that
inhere in the plain-view context.3

															The Minnesota Supreme Court rejected an analogy to the
plain-view doctrine on two grounds: first, its belief that "the
sense of touch is inherently less immediate and less reliable than
the sense of sight," and second, that "the sense of touch is far
more intrusive into the personal privacy that is at the core of the
[F]ourth [A]mendment." 481 N. W. 2d, at 845. We have a somewhat
different view. First, Terry itself demonstrates that the
sense of touch is capable of revealing the nature of an object with
sufficient reliability to support a seizure. The very premise of Terry, after all, is that officers will be able to detect
the presence of weapons through the sense of touch and Terry upheld precisely such a seizure. Even if it were true that the
sense of touch is generally less reliable than the sense of sight,
that only suggests that officers will less often be able to justify
seizures of unseen contraband. Regardless of whether the officer
detects the contraband by sight or by touch, however, the Fourth
Amendment's requirement that the officer have probable cause to
believe that the item is contraband before seizing it ensures
against excessively speculative seizures.4 The

															3 "[T]he police officer in each [case would have] had a prior
justification for an intrusion in the course of which he came
inadvertently across a piece of evidence incriminating the accused.
The doctrine serves to supplement the prior justification ... and
permits the warrantless seizure." Coolidge v. New
Hampshire, 403 U.
S. 443 , 466 (1971) (opinion of Stewart, J.).

															4 We also note that this Court's opinion in Ybarra v. Illinois, 444
U. S. 85 (1979), appeared to contemplate the possibility that
police officers could obtain probable cause justifying a seizure of
contraband through the sense of touch. In that case, police
officers had entered a tavern and subjected its patrons to patdown
searches. While patting down the petitioner Ybarra, an "officer
felt what he described as 'a cigarette pack with objects in it,'"
seized it, and discovered heroin inside. Id., at 88-89. The
State argued that the seizure was constitutional on the grounds
that the officer obtained probable cause to believe that Ybarra was
carrying contraband during the course of a lawful Terry frisk. Ybarra, supra, at 92. This 377 court's second concern-that touch is more intrusive into privacy
than is sight-is inapposite in light of the fact that the intrusion
the court fears has already been authorized by the lawful search
for weapons. The seizure of an item whose identity is already known
occasions no further invasion of privacy. See Soldal v. Cook County, 506 U. S. 56 , 66 (1992); Horton, supra, at 141; United States v. Jacobsen, 466 U. S. 109, 120 (1984). Accordingly, the
suspect's privacy interests are not advanced by a categorical rule
barring the seizure of contraband plainly detected through the
sense of touch.

															III

															It remains to apply these principles to the facts of this case.
Respondent has not challenged the finding made by the trial court
and affirmed by both the Court of Appeals and the State Supreme
Court that the police were justified under Terry in stopping
him and frisking him for weapons. Thus, the dispositive question
before this Court is whether the officer who conducted the search
was acting within the lawful bounds marked by Terry at the
time he gained probable cause to believe that the lump in
respondent's jacket was contraband. The State District Court did
not make precise findings on this point, instead finding simply
that the officer, after feeling "a small, hard object wrapped in
plastic" in respondent's pocket, "formed the opinion that the
object ... was crack ... cocaine." App. to Pet. for Cert. C-2.
The

															Court rejected that argument on the grounds that "[t]he initial
frisk of Ybarra was simply not supported by a reasonable belief
that he was armed and presently dangerous," as required by Terry. 444 U. S., at 92-93. The Court added: "[s]ince we
conclude that the initial patdown of Ybarra was not justified under
the Fourth and Fourteenth Amendments, we need not decide whether or
not the presence on Ybarra's person of 'a cigarette pack with
objects in it' yielded probable cause to believe that Ybarra was
carrying any illegal substance." Id., at 93, n. 5. The
Court's analysis does not suggest, and indeed seems inconsistent
with, the existence of a categorical bar against seizures of
contraband detected manually during a Terry patdown
search. 378 District Court also noted that the officer made "no claim that
he suspected this object to be a weapon," id., at C-5, a finding
affirmed on appeal, see 469 N. W. 2d, at 464 (the officer "never
thought the lump was a weapon"). The Minnesota Supreme Court, after
"a close examination of the record," held that the officer's own
testimony "belies any notion that he 'immediately'" recognized the
lump as crack cocaine. See 481 N. W. 2d, at 844. Rather, the court
concluded, the officer determined that the lump was contraband only
after "squeezing, sliding and otherwise manipulating the contents
of the defendant's pocket"-a pocket which the officer already knew
contained no weapon. Ibid. Under the State Supreme Court's interpretation of the record
before it, it is clear that the court was correct in holding that
the police officer in this case overstepped the bounds of the
"strictly circumscribed" search for weapons allowed under Terry. See Terry, 392 U. S., at 26. Where, as here,
"an officer who is executing a valid search for one item seizes a
different item," this Court rightly "has been sensitive to the
danger ... that officers will enlarge a specific authorization,
furnished by a warrant or an exigency, into the equivalent of a
general warrant to rummage and seize at will." Texas v. Brown, 460 U. S., at 748 (STEVENS, J., concurring in
judgment). Here, the officer's continued exploration of
respondent's pocket after having concluded that it contained no
weapon was unrelated to "[t]he sole justification of the search
[under Terry:] ... the protection of the police officer and
others nearby." 392 U. S., at 29. It therefore amounted to the sort
of evidentiary search that Terry expressly refused to
authorize, see id., at 26, and that we have condemned in subsequent
cases. See Michigan v. Long, 463 U. S., at 1049, n.
14; Sibron, 392 U. S., at 65-66.

															Once again, the analogy to the plain-view doctrine is apt.

															In Arizona v. Hicks, 480 U. S. 321 (1987),
this Court held invalid the seizure of stolen stereo equipment
found by police while executing a valid search for other evidence.
Although 379 the police were lawfully on the premises, they obtained probable
cause to believe that the stereo equipment was contraband only
after moving the equipment to permit officers to read its serial
numbers. The subsequent seizure of the equipment could not be
justified by the plain-view doctrine, this Court explained, because
the incriminating character of the stereo equipment was not
immediately apparent; rather, probable cause to believe that the
equipment was stolen arose only as a result of a further search-the
moving of the equipment-that was not authorized by a search warrant
or by any exception to the warrant requirement. The facts of this
case are very similar. Although the officer was lawfully in a
position to feel the lump in respondent's pocket, because Terry entitled him to place his hands upon respondent's
jacket, the court below determined that the incriminating character
of the object was not immediately apparent to him. Rather, the
officer determined that the item was contraband only after
conducting a further search, one not authorized by Terry or
by any other exception to the warrant requirement. Because this
further search of respondent's pocket was constitutionally invalid,
the seizure of the cocaine that followed is likewise
unconstitutional. Horton, 496 U. S., at 140.

															IV

															For these reasons, the judgment of the Minnesota Supreme Court
is

															Affirmed.

															JUSTICE SCALIA, concurring.

															I take it to be a fundamental principle of constitutional
adjudication that the terms in the Constitution must be given the
meaning ascribed to them at the time of their ratification. Thus,
when the Fourth Amendment provides that "[t]he right of the people
to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated"
(emphasis added), it "is 380 to be construed in the light of what was deemed an unreasonable
search and seizure when it was adopted," Carroll v. United States, 267 U. S. 132 , 149
(1925); see also California v. Acevedo, 500 U. S. 565 , 583-584
(1991) (SCALIA, J., concurring in judgment). The purpose of the
provision, in other words, is to preserve that degree of respect
for the privacy of persons and the inviolability of their property
that existed when the provision was adopted-even if a later, less
virtuous age should become accustomed to considering all sorts of
intrusion "reasonable."

															My problem with the present case is that I am not entirely sure
that the physical search-the "frisk"-that produced the evidence at
issue here complied with that constitutional standard. The decision
of ours that gave approval to such searches, Terry v. Ohio, 392 U. S.
1 (1968), made no serious attempt to determine compliance with
traditional standards, but rather, according to the style of this
Court at the time, simply adjudged that such a search was
"reasonable" by current estimations. Id., at 22-27.

															There is good evidence, I think, that the "stop" portion of the Terry "stop-and-frisk" holding accords with the common
law-that it had long been considered reasonable to detain
suspicious persons for the purpose of demanding that they give an
account of themselves. This is suggested, in particular, by the
so-called night-walker statutes, and their common-law antecedents.
See Statute of Winchester, 13 Edw. I, Stat. 2, ch. 4 (1285);
Statute of 5 Edw. III, ch. 14 (1331); 2 W. Hawkins, Pleas of the
Crown, ch. 13, § 6, p. 129 (8th ed. 1824) ("It is holden that this
statute was made in affirmance of the common law, and that every
private person may by the common law arrest any suspicious
night-walker, and detain him till he give a good account of
himself"); 1 E. East, Pleas of the Crown, ch. 5, § 70, p. 303
(1803) ("It is said ... that every private person may by the common
law arrest any suspicious night-walker, and detain him till he give
a good account of himself"); see also M. Dalton, The Country 381 Justice, ch. 104, pp. 352-353 (1727); A. Costello, Our Police
Protectors: History of the New York Police 25 (1885) (citing 1681
New York City regulation); 2 Perpetual Laws of Massachusetts
1788-1798, ch. 82, §2, p. 410 (1797 Massachusetts statute).

															I am unaware, however, of any precedent for a physical search of
a person thus temporarily detained for questioning. Sometimes, of
course, the temporary detention of a suspicious character would be
elevated to a full custodial arrest on probable cause-as, for
instance, when a suspect was unable to provide a sufficient
accounting of himself. At that point, it is clear that the common
law would permit not just a protective "frisk," but a full physical
search incident to the arrest. When, however, the detention did not
rise to the level of a full-blown arrest (and was not supported by
the degree of cause needful for that purpose), there appears to be
no clear support at common law for physically searching the
suspect. See Warner, The Uniform Arrest Act, 28 Va. L. Rev. 315,
324 (1942) ("At common law, if a watchman came upon a suspiciously
acting nightwalker, he might arrest him and then search him for
weapons, but he had no right to search before arrest"); Williams,
Police Detention and Arrest Privileges-England, 51 J. Crim. L., C.
& P. S. 413, 418 (1960) ("Where a suspected criminal is also
suspected of being offensively armed, can the police search him for
arms, by tapping his pockets, before making up their minds whether
to arrest him? There is no English authority ... ").

															I frankly doubt, moreover, whether the fiercely proud men who
adopted our Fourth Amendment would have allowed themselves to be
subjected, on mere suspicion of being armed and dangerous,
to such indignity-which is described as follows in a police
manual: "Check the subject's neck and collar. A check should be made
under the subject's arm. Next a check should be made of the upper
back. The lower back should also be checked. 382 "A check should be made of the upper part of the man's chest and
the lower region around the stomach. The belt, a favorite
concealment spot, should be checked. The inside thigh and crotch
area also should be searched. The legs should be checked for
possible weapons. The last items to be checked are the shoes and
cuffs of the subject." J. Moynahan, Police Searching Procedures 7
(1963) (citations omitted). On the other hand, even if a "frisk" prior to arrest would have
been considered impermissible in 1791, perhaps it was considered
permissible by 1868, when the Fourteenth Amendment (the basis for
applying the Fourth Amendment to the States) was adopted. Or
perhaps it is only since that time that concealed weapons capable
of harming the interrogator quickly and from beyond arm's reach
have become common-which might alter the judgment of what is
"reasonable" under the original standard. But technological changes
were no more discussed in Terry than was the original state
of the law.

															If I were of the view that Terry was (insofar as the
power to "frisk" is concerned) incorrectly decided, I might-even if
I felt bound to adhere to that case-vote to exclude the evidence
incidentally discovered, on the theory that half a constitutional
guarantee is better than none. I might also vote to exclude it if I
agreed with the original-meaning-isirrelevant,
good-policy-is-constitutional-Iaw school of jurisprudence that the Terry opinion represents. As a policy matter, it may be
desirable to permit "frisks" for weapons, but not to encourage "frisks" for drugs by admitting evidence other
than weapons.

															I adhere to original meaning, however. And though I do not favor
the mode of analysis in Terry, I cannot say that its result
was wrong. Constitutionality of the "frisk" in the present case was
neither challenged nor argued. Assuming, therefore, that the search
was lawful, I agree with the Court's premise that any evidence
incidentally discovered in 383 the course of it would be admissible, and join the Court's
opinion in its entirety.

															CHIEF JUSTICE REHNQUIST, with whom JUSTICE BLACKMUN and JUSTICE
THOMAS join, concurring in part and dissenting in part.

															I join Parts I and II of the Court's opinion. Unlike the Court,
however, I would vacate the judgment of the Supreme Court of
Minnesota and remand the case to that court for further
proceedings.

															The Court, correctly in my view, states that "the dispositive
question before this Court is whether the officer who conducted the
search was acting within the lawful bounds marked by Terry [v. Ohio, 392 U.
S. 1 (1968),] at the time he gained probable cause to believe
that the lump in respondent's jacket was contraband." Ante, at 377. The Court then goes on to point out that the state trial
court did not make precise findings on this point, but accepts the
appellate findings made by the Supreme Court of Minnesota. I
believe that these findings, like those of the trial court, are
imprecise and not directed expressly to the question of the
officer's probable cause to believe that the lump was contraband.
Because the Supreme Court of Minnesota employed a Fourth Amendment
analysis which differs significantly from that now adopted by this
Court, I would vacate its judgment and remand the case for further
proceedings there in the light of this Court's opinion.

Summary:
The Supreme Court ruled that police may seize non-threatening contraband detected through touch during a protective pat-down search, as long as the search stays within the bounds set by Terry v. Ohio (1968). The Court upheld the "plain-feel" exception to the Fourth Amendment's warrant requirement, allowing officers to seize contraband if they are lawfully in a position to feel it and it is immediately apparent that the object is contraband. However, the Court emphasized that the protective search must be strictly limited to ensuring the safety of the officer and others.

Justice Scalia concurred, noting the originalist approach to the Fourth Amendment and questioning the "frisk" aspect of Terry. He agreed with the Court's premise that any evidence discovered during a lawful search would be admissible.

Chief Justice Rehnquist, joined by Justices Blackmun and Thomas, concurred in part and dissented in part. They agreed with the Court's analysis but disagreed with the findings of the Minnesota Supreme Court, believing they were imprecise. They would have vacated the judgment and remanded the case for further proceedings.


U.S. Supreme Court Florida v. Riley, 488
U.S. 445 (1989) Florida v. Riley No. 87-764 Argued October 3,
1988 Decided January 23,
1989 488
U.S. 445 CERTIORARI TO THE SUPREME COURT OF
FLORIDA Syllabus A Florida county sheriff's office received an anonymous tip that
marijuana was being grown on respondent's property. When an
investigating officer discovered that he could not observe from
Found level the contents of a greenhouse on the property -- which
was enclosed on two sides and obscured from view on the other, open
sides by trees, shrubs, and respondent's nearby home -- he circled
twice over the property in a helicopter at the height of 400 feet
and made naked-eye observations through openings in the greenhouse
roof and its open sides of what he concluded were marijuana plants.
After a search pursuant to a warrant obtained on the basis of these
observations revealed marijuana growing in the greenhouse,
respondent was charged with possession of that substance under
Florida law. The trial court granted his motion to suppress the
evidence. Although reversing, the State Court of Appeals certified
the case to the State Supreme Court on the question whether the
helicopter surveillance from 400 feet constituted a "search" for
which a warrant was required under the Fourth Amendment. Answering
that question in the affirmative, the court quashed the Court of
Appeals' decision and reinstated the trial court's suppression
order. Held: The judgment is reversed. 511 So. 2d
282 , reversed.

															JUSTICE WHITE, joined by THE CHIEF JUSTICE, JUSTICE SCALIA, and
JUSTICE KENNEDY, concluded that the Fourth Amendment does not
require the police traveling in the public airways at an altitude
of 400 feet to obtain a warrant in order to observe what is visible
to the naked eye. California v. Ciraolo, 476 U.
S. 207 -- which held that a naked-eye police inspection
of the backyard of a house from a fixed-wing aircraft at 1,000 feet
was not a "search" -- is controlling. Thus, respondent could not
reasonably have expected that the contents of his greenhouse were
protected from public or official inspection from the air, since he
left the greenhouse's sides and roof partially open. The fact that
the inspection was made from a helicopter is irrelevant, since, as
in the case of fixed-wing planes, private and commercial flight by
helicopter is routine. Nor, on the facts of this case, does it make
a difference for Fourth Amendment purposes that the helicopter was
flying below 500 feet, the Federal Aviation Administration's lower
limit upon the navigable airspace for fixed-wing craft. Since the
FAA permits helicopters to fly Page 488 U. S. 446 below that limit, the helicopter here was not violating the law,
and any member of the public or the police could legally have
observed respondent's greenhouse from that altitude. Although an
aerial inspection of a house's curtilage may not always pass muster
under the Fourth Amendment simply because the aircraft is within
the navigable airspace specified by law, there is nothing in the
record here to suggest that helicopters flying at 400 feet are
sufficiently rare that respondent could have reasonably anticipated
that his greenhouse would not be observed from that altitude.
Moreover, there is no evidence that the helicopter interfered with
respondent's normal use of his greenhouse or other parts of the
curtilage, that intimate details connected with the use of the home
or curtilage were observed, or that there was undue noise, wind,
dust, or threat of injury. Pp. 488 U. S.
449 -452.

															JUSTICE O'CONNOR concluded that the plurality's approach rests
the scope of Fourth Amendment protection too heavily on compliance
with FAA regulations, which are intended to promote air safety, and
not to protect the right to be secure against unreasonable searches
and seizures. Whether respondent had a reasonable expectation of
privacy from aerial observation of his curtilage does not depend on
whether the helicopter was where it had a right to be, but, rather,
on whether it was in the public airways at an altitude at which
members of the public travel with sufficient regularity that
respondent's expectation was not one that society is prepared to
recognize as "reasonable." Because there is reason to believe that
there is considerable public use of airspace at altitudes of 400
feet and above, and because respondent introduced no evidence to
the contrary before the state courts, it must be concluded that his
expectation of privacy here was not reasonable. However, public use
of altitudes lower than 400 feet -- particularly public
observations from helicopters circling over the curtilage of a home
-- may be sufficiently rare that police surveillance from such
altitudes would violate reasonable expectations of privacy, despite
compliance with FAA regulations. Pp. 488 U. S.
452 -455.

															WHITE, J., announced the judgment of the Court and delivered an
opinion in which REHNQUIST, C.J., and SCALIA and KENNEDY, JJ.,
joined. O'CONNOR, J., filed an opinion concurring in the judgment, post, p. 488 U. S. 452 .
BRENNAN, J., filed a dissenting opinion, in which MARSHALL and
STEVENS, JJ., joined, post, p. 488 U. S. 456 .
BLACKMUN, J., filed a dissenting opinion, post, p. 488 U. S.
467 . Page 488 U. S. 447 JUSTICE WHITE announced the judgment of the Court and delivered
an opinion, in which THE CHIEF JUSTICE, JUSTICE SCALIA, and JUSTICE
KENNEDY join.

															On certification to it by a lower state court, the Florida
Supreme Court addressed the following question:

															"Whether surveillance of the interior of a partially covered
greenhouse Page 488 U. S. 448 in a residential backyard from the vantage point of a helicopter
located 400 feet above the greenhouse constitutes a 'search' for
which a warrant is required under the Fourth Amendment and Article
I, § 12 of the Florida Constitution." 511 So. 2d
282 (1987). The court answered the question in the affirmative,
and we granted the State's petition for certiorari challenging that
conclusion. 484 U.S. 1058 (1988). [ Footnote 1 ]

															Respondent Riley lived in a mobile home located on five acres of
rural property. A greenhouse was located 10 to 20 feet behind the
mobile home. Two sides of the greenhouse were enclosed. The other
two sides were not enclosed, but the contents of the greenhouse
were obscured from view from surrounding property by trees, shrubs,
and the mobile home. The greenhouse was covered by corrugated
roofing panels, some translucent and some opaque. At the time
relevant to this case, two of the panels, amounting to
approximately 10% of the roof area, were missing. A wire fence
surrounded the mobile home and the greenhouse, and the property was
posted with a "DO NOT ENTER" sign.

															This case originated with an anonymous tip to the Pasco County
Sheriff's office that marijuana was being grown on respondent's
property. When an investigating officer discovered that he could
not see the contents of the greenhouse from the road, he circled
twice over respondent's property in a helicopter at the height of
400 feet. With his naked eye, he was able to see through the
openings in the roof and one or more of the open sides of the
greenhouse and to identify what he thought was marijuana growing in
the structure. A warrant Page 488 U. S. 449 was obtained based on these observations, and the ensuing search
revealed marijuana growing in the greenhouse. Respondent was
charged with possession of marijuana under Florida law. The trial
court granted his motion to suppress; the Florida Court of Appeals
reversed, but certified the case to the Florida Supreme Court,
which quashed the decision of the Court of Appeals and reinstated
the trial court's suppression order.

															We agree with the State's submission that our decision in California v. Ciraolo, 476 U. S. 207 (1986), controls this case. There, acting on a tip, the police
inspected the backyard of a particular house while flying in a
fixed-wing aircraft at 1,000 feet. With the naked eye the officers
saw what they concluded was marijuana growing in the yard. A search
warrant was obtained on the strength of this airborne inspection,
and marijuana plants were found. The trial court refused to
suppress this evidence, but a state appellate court held that the
inspection violated the Fourth and Fourteenth Amendments to the
United States Constitution, and that the warrant was therefore
invalid. We in turn reversed, holding that the inspection was not a
search subject to the Fourth Amendment. We recognized that the yard
was within the curtilage of the house, that a fence shielded the
yard from observation from the street, and that the occupant had a
subjective expectation of privacy. We held, however, that such an
expectation was not reasonable, and not one "that society is
prepared to honor." Id. at 476 U. S. 214 .
Our reasoning was that the home and its curtilage are not
necessarily protected from inspection that involves no physical
invasion. " What a person knowingly exposes to the public, even
in his own home or office, is not a subject of Fourth Amendment
protection.'" Id. at 213, quoting Katz v. United
States, 389 U. S. 347 , 389 U. S. 351 (1967). As a general proposition, the police may see what may be
seen "from a public vantagepoint where [they have] a right to be,"
476 U.S. at 476 U. S. 213 .
Thus the police, like the public, would have been free to inspect
the backyard garden from Page 488 U. S. 450 the street if their view had been unobstructed. They were
likewise free to inspect the yard from the vantage point of an
aircraft flying in the navigable airspace as this plane was.

															"In an age where private and commercial flight in the public
airways is routine, it is unreasonable for respondent to expect
that his marijuana plants were constitutionally protected from
being observed with the naked eye from an altitude of 1,000 feet.
The Fourth Amendment simply does not require the police traveling
in the public airways at this altitude to obtain a warrant in order
to observe what is visible to the naked eye." Id. at 476 U. S.
215 .

															We arrive at the same conclusion in the present case. In this
case, as in Ciraolo, the property surveyed was within the
curtilage of respondent's home. Riley no doubt intended and
expected that his greenhouse would not be open to public
inspection, and the precautions he took protected against
ground-level observation. Because the sides and roof of his
greenhouse were left partially open, however, what was growing in
the greenhouse was subject to viewing from the air. Under the
holding in Ciraolo, Riley could not reasonably Page 488 U. S. 451 have expected the contents of his greenhouse to be immune from
examination by an officer seated in a fixed-wing aircraft flying in
navigable airspace at an altitude of 1,000 feet or, as the Florida
Supreme Court seemed to recognize, at an altitude of 500 feet, the
lower limit of the navigable airspace for such an aircraft. 511 So.
2d at 288. Here, the inspection was made from a helicopter, but, as
is the case with fixed-wing planes, "private and commercial flight
[by helicopter] in the public airways is routine" in this country, Ciraolo, supra, at 476 U. S. 215 ,
and there is no indication that such flights are unheard of in
Pasco County, Florida. [ Footnote
2 ] Riley could not reasonably have expected that his greenhouse
was protected from public or official observation from a helicopter
had it been flying within the navigable airspace for fixed-wing
aircraft.

															Nor on the facts before us, does it make a difference for Fourth
Amendment purposes that the helicopter was flying at 400 feet when
the officer saw what was growing in the greenhouse through the
partially open roof and sides of the structure. We would have a
different case if flying at that altitude had been contrary to law
or regulation. But helicopters are not bound by the lower limits of
the navigable airspace allowed to other aircraft. [ Footnote 3 ] Any member of the public could
legally have been flying over Riley's property in a helicopter at
the altitude of 400 feet, and could have observed Riley's
greenhouse. The police officer did no more. This is not to say that
an inspection of the curtilage of a house from an aircraft will
always pass muster under the Fourth Amendment simply because the
plane is within the navigable airspace specified by law. But it is
of obvious importance that the helicopter in this case was not violating the law, and there is nothing in the record
or before us to suggest that helicopters flying at 400 feet are
sufficiently rare in this country to lend substance to respondent's
claim that he reasonably anticipated that his greenhouse would not
be subject to Page 488 U. S. 452 observation from that altitude. Neither is there any intimation
here that the helicopter interfered with respondent's normal use of
the greenhouse or of other parts of the curtilage. As far as this
record reveals, no intimate details connected with the use of the
home or curtilage were observed, and there was no undue noise, and
no wind, dust, or threat of injury. In these circumstances, there
was no violation of the Fourth Amendment.

															The judgment of the Florida Supreme Court is accordingly
reversed. So ordered. [ Footnote 1 ]

															The Florida Supreme Court mentioned the State Constitution in
posing the question, once in the course of its opinion, and again
in finally concluding that the search violated the Fourth Amendment
and the State Constitution. The bulk of the discussion, however,
focused exclusively on federal cases dealing with the Fourth
Amendment, and there being no indication that the decision "clearly
and expressly . . . is alternatively based on bona fide separate,
adequate, and independent grounds," we have jurisdiction. Michigan v. Long, 463 U. S. 1032 , 463 U. S.
1041 (1983).

															[ Footnote 2 ]

															The first use of the helicopter by police was in New York in
1947, and today every State in the country uses helicopters in
police work. As of 1980, there were 1,500 such aircraft used in
police work. E. Brown, The Helicopter in Civil Operations 79
(1981). More than 10,000 helicopters, both public and private, are
registered in the United States. Federal Aviation Administration,
Census of U.S. Civil Aircraft, Calendar Year 1987, p. 12. See
also 1988 Helicopter Annual 9. And there are an estimated
31,697 helicopter pilots. Federal Aviation Administration,
Statistical Handbook of Aviation, Calendar Year 1986, p. 147.

															[ Footnote 3 ]

															While Federal Aviation Administration (FAA) regulations permit
fixed-wing aircraft to be operated at an altitude of 1,000 feet
while flying over congested areas and at an altitude of 500 feet
above the surface in other than congested areas, helicopters may be
operated at less than the minimums for fixed-wing aircraft

															"if the operation is conducted without hazard to persons or
property on the surface. In addition, each person operating a
helicopter shall comply with routes or altitudes specifically
prescribed for helicopters by the [FAA] Administrator."

															14 CFR § 91.79 (1988).

															JUSTICE O'CONNOR, concurring in the judgment.

															I concur in the judgment reversing the Supreme Court of Florida
because I agree that police observation of the greenhouse in
Riley's curtilage from a helicopter passing at an altitude of 400
feet did not violate an expectation of privacy "that society is
prepared to recognize as reasonable.'" Katz v. United
States, 389 U. S. 347 , 389 U. S. 361 (1967) (Harlan, J., concurring). I write separately, however, to
clarify the standard I believe follows from California v.
Ciraolo, 476 U. S. 207 (1986). In my view, the plurality's approach rests the scope of
Fourth Amendment protection too heavily on compliance with FAA
regulations whose purpose is to promote air safety, not to protect
"[t]he right of the people to be secure in their persons, houses,
papers, and effects, against unreasonable searches and seizures."
U.S.Const., Amdt. 4. Ciraolo involved observation of curtilage by officers
flying in an airplane at an altitude of 1,000 feet. In evaluating
whether this observation constituted a search for which a warrant
was required, we acknowledged the importance of curtilage in Fourth
Amendment doctrine:

															"The protection afforded the curtilage is essentially a
protection of families and personal privacy in an area intimately
linked to the home, both physically and psychologically, where
privacy expectations are most heightened."

															476 U.S. at 476 U. S.
212 -213. Although the curtilage is an area to which the
private activities Page 488 U. S. 453 of the home extend, all police observation of the curtilage is
not necessarily barred by the Fourth Amendment. As we observed:

															"The Fourth Amendment protection of the home has never been
extended to require law enforcement officers to shield their eyes
when passing by a home on public thoroughfares." Id. at 476 U. S. 213 .
In Ciraolo, we likened observation from a plane traveling
in "public navigable airspace" at 1,000 feet to observation by
police "passing by a home on public thoroughfares." We held that
"[i]n an age where private and commercial flight in the public
airways is routine," it is unreasonable to expect the curtilage to
be constitutionally protected from aerial observation with the
naked eye from an altitude of 1,000 feet. Id. at 476 U. S.
215 .

															Ciraolo's expectation of privacy was unreasonable not because
the airplane was operating where it had a "right to be," but
because public air travel at 1,000 feet is a sufficiently routine
part of modern life that it is unreasonable for persons on the
ground to expect that their curtilage will not be observed from the
air at that altitude. Although "helicopters are not bound by the
lower limits of the navigable airspace allowed to other aircraft," ante at 488 U. S. 451 ,
there is no reason to assume that compliance with FAA regulations
alone determines " whether the government's intrusion infringes
upon the personal and societal values protected by the Fourth
Amendment.'" Ciraolo, supra, at 476 U. S. 212 (quoting Oliver v. United States, 466 U.
S. 170 , 466 U. S.
182 -183 (1984)). Because the FAA has decided that
helicopters can lawfully operate at virtually any altitude so long
as they pose no safety hazard, it does not follow that the
expectations of privacy "society is prepared to recognize as
`reasonable'" simply mirror the FAA's safety concerns. Observations of curtilage from helicopters at very low altitudes
are not perfectly analogous to ground-level observations from
public roads or sidewalks. While in both cases the police may have
a legal right to occupy the physical space from which their
observations are made, the two situations Page 488 U. S. 454 are not necessarily comparable in terms of whether expectations
of privacy from such vantage points should be considered
reasonable. Public roads, even those less traveled by, are clearly
demarked public thoroughfares. Individuals who seek privacy can
take precautions, tailored to the location of the road, to avoid
disclosing private activities to those who pass by. They can build
a tall fence, for example, and thus ensure private enjoyment of the
curtilage without risking public observation from the road or
sidewalk. If they do not take such precautions, they cannot
reasonably expect privacy from public observation. In contrast,
even individuals who have taken effective precautions to ensure
against ground-level observations cannot block off all conceivable
aerial views of their outdoor patios and yards without entirely
giving up their enjoyment of those areas. To require individuals to
completely cover and enclose their curtilage is to demand more than
the "precautions customarily taken by those seeking privacy." Rakas v. Illinois, 439 U. S. 128 , 439 U. S. 152 (1978) (Powell, J., concurring). The fact that a helicopter could
conceivably observe the curtilage at virtually any altitude or
angle, without violating FAA regulations, does not in itself mean
that an individual has no reasonable expectation of privacy from
such observation.

															In determining whether Riley had a reasonable expectation of
privacy from aerial observation, the relevant inquiry after Ciraolo is not whether the helicopter was where it had a
right to be under FAA regulations. Rather, consistent with Katz, we must ask whether the helicopter was in the public
airways at an altitude at which members of the public travel with
sufficient regularity that Riley's expectation of privacy from
aerial observation was not "one that society is prepared to
recognize as reasonable.'" Katz, supra, at 361. Thus,
in determining "`whether the government's intrusion infringes upon
the personal and societal values protected by the Fourth
Amendment,'" Ciraolo, supra, at 476 U. S. 212 (quoting Oliver, supra, at 466 U. S.
182 -183), it is not conclusive to observe, Page 488 U. S. 455 as the plurality does, that "[a]ny member of the public could
legally have been flying over Riley's property in a helicopter at
the altitude of 400 feet, and could have observed Riley's
greenhouse." Ante at 451. Nor is it conclusive that police
helicopters may often fly at 400 feet. If the public rarely, if
ever, travels overhead at such altitudes, the observation cannot be
said to be from a vantage point generally used by the public, and
Riley cannot be said to have "knowingly expose[d]" his greenhouse
to public view. However, if the public can generally be expected to
travel over residential backyards at an altitude of 400 feet, Riley
cannot reasonably expect his curtilage to be free from such aerial
observation.

															In my view, the defendant must bear the burden of proving that
his expectation of privacy was a reasonable one, and thus that a
"search" within the meaning of the Fourth Amendment even took
place. Cf. Jones v. United States, 362 U.
S. 257 , 362 U. S. 261 (1960) ("Ordinarily, then, it is entirely proper to require of one
who seeks to challenge the legality of a search as the basis for
suppressing relevant evidence that he allege, and if the allegation
be disputed that he establish, that he himself was the victim of an
invasion of privacy"); Nardone v. United States, 308 U. S. 338 , 308 U. S. 341 (1939).

															Because there is reason to believe that there is considerable
public use of airspace at altitudes of 400 feet and above, and
because Riley introduced no evidence to the contrary before the
Florida courts, I conclude that Riley's expectation that his
curtilage was protected from naked-eye aerial observation from that
altitude was not a reasonable one. However, public use of altitudes
lower than that -- particularly public observations from
helicopters circling over the curtilage of a home -- may be
sufficiently rare that police surveillance from such altitudes
would violate reasonable expectations of privacy, despite
compliance with FAA air safety regulations Page 488 U. S. 456 JUSTICE BRENNAN, with whom JUSTICE MARSHALL and JUSTICE STEVENS
join, dissenting.

															The Court holds today that police officers need not obtain a
warrant based on probable cause before circling in a helicopter 400
feet above a home in order to investigate what is taking place
behind the walls of the curtilage. I cannot agree that the Fourth
Amendment to the Constitution, which safeguards "[t]he right of the
people to be secure in their persons, houses, papers, and effects,
against unreasonable searches and seizures," tolerates such an
intrusion on privacy and personal security. I The opinion for a plurality of the Court reads almost as if Katz v. United States, 389 U. S. 347 (1967), had never been decided. Notwithstanding the disclaimers of
its final paragraph, the opinion relies almost exclusively on the
fact that the police officer conducted his surveillance from a
vantage point where, under applicable Federal Aviation
Administration regulations, he had a legal right to be. Katz teaches, however, that the relevant inquiry is
whether the police surveillance "violated the privacy upon which
[the defendant] justifiably relied," id. at 389 U. S. 353 -- or, as Justice Harlan put it, whether the police violated an
"expectation of privacy . . . that society is prepared to recognize
as reasonable.'" Id. at 389 U. S. 361 (concurring opinion). The result of that inquiry in any given case
depends ultimately on the judgment "whether, if the particular form of surveillance practiced by
the police is permitted to go unregulated by constitutional
restraints, the amount of privacy and freedom remaining to citizens
would be diminished to a compass inconsistent with the aims of a
free and open society."

															Amsterdam, Perspectives on the Fourth Amendment, 58 Minn.L.Rev.
349, 403 (1974); see also 1 W. LaFave, Search and Seizure
§ 2.1(d), pp. 310-314 (2d ed.1987).

															The plurality undertakes no inquiry into whether low-level
helicopter surveillance by the police of activities in an
enclosed Page 488 U. S. 457 backyard is consistent with the "aims of a free and open
society." Instead, it summarily concludes that Riley's expectation
of privacy was unreasonable because

															"[a]ny member of the public could legally have been flying over
Riley's property in a helicopter at the altitude of 400 feet and
could have observed Riley's greenhouse." Ante at 488 U. S. 451 .
This observation is, in turn, based solely on the fact that the
police helicopter was within the airspace within which such craft
are allowed by federal safety regulations to fly.

															I agree, of course, that "[w]hat a person knowingly exposes to
the public . . . is not a subject of Fourth Amendment protection." Katz, supra, at 389 U. S. 351 .
But I cannot agree that one "knowingly exposes [an area] to the
public" solely because a helicopter may legally fly above it. Under
the plurality's exceedingly grudging Fourth Amendment theory, the
expectation of privacy is defeated if a single member of the public
could conceivably position herself to see into the area in question
without doing anything illegal. It is defeated whatever the
difficulty a person would have in so positioning herself, and
however infrequently anyone would in fact do so. In taking this
view, the plurality ignores the very essence of Katz. The
reason why there is no reasonable expectation of privacy in an area
that is exposed to the public is that little diminution in "the
amount of privacy and freedom remaining to citizens" will result
from police surveillance of something that any passerby readily
sees. To pretend, as the plurality opinion does, that the same is
true when the police use a helicopter to peer over high fences is,
at best, disingenuous. Notwithstanding the plurality's statistics
about the number of helicopters registered in this country, can it
seriously be questioned that Riley enjoyed virtually complete
privacy in his backyard greenhouse, and that that privacy was
invaded solely by police helicopter surveillance? Is the
theoretical possibility that any member of the public (with
sufficient means) could also have hired a helicopter and looked
over Riley's fence of any relevance at all in determining Page 488 U. S. 458 whether Riley suffered a serious loss of privacy and personal
security through the police action?

															In California v. Ciraolo, 476 U.
S. 207 (1986), we held that whatever might be observed
from the window of an airplane flying at 1,000 feet could be deemed
unprotected by any reasonable expectation of privacy. That decision
was based on the belief that airplane traffic at that altitude was
sufficiently common that no expectation of privacy could inure in
anything on the ground observable with the naked eye from so high.
Indeed, we compared those airways to "public thoroughfares," and
made the obvious point that police officers passing by a home on
such thoroughfares were not required by the Fourth Amendment to
"shield their eyes." Id. at 476 U. S. 213 .
Seizing on a reference in Ciraolo to the fact that the
police officer was in a position "where he ha[d] a right to be," ibid., today's plurality professes to find this case
indistinguishable because FAA regulations do not impose a minimum
altitude requirement on helicopter traffic; thus, the officer in
this case too made his observations from a vantage point where he
had a right to be. [ Footnote
2/1 ]

															It is a curious notion that the reach of the Fourth Amendment
can be so largely defined by administrative regulations issued for
purposes of flight safety. [ Footnote
2/2 ] It is more curious still Page 488 U. S. 459 that the plurality relies to such an extent on the legality of
the officer's act, when we have consistently refused to equate
police violation of the law with infringement of the Fourth
Amendment. [ Footnote 2/3 ] But the
plurality's willingness to end its inquiry when it finds that the
officer was in a position he had a right to be in is misguided for
an even more fundamental reason. Finding determinative the fact
that the officer was where he had a right to be is, at bottom, an
attempt to analogize surveillance from a helicopter to surveillance
by a police officer standing on a public road and viewing evidence
of crime through an open window or a gap in a fence. In such a
situation, the occupant of the home may be said to lack any Page 488 U. S. 460 reasonable expectation of privacy in what can be seen from that
road -- even if, in fact, people rarely pass that way.

															The police officer positioned 400 feet above Riley's backyard
was not, however, standing on a public road. The vantage point he
enjoyed was not one any citizen could readily share. His ability to
see over Riley's fence depended on his use of a very expensive and
sophisticated piece of machinery to which few ordinary citizens
have access. In such circumstances, it makes no more sense to rely
on the legality of the officer's position in the skies than it
would to judge the constitutionality of the wiretap in Katz by the legality of the officer's position outside the
telephone booth. The simple inquiry whether the police officer had
the legal right to be in the position from which he made his
observations cannot suffice, for we cannot assume that Riley's
curtilage was so open to the observations of passersby in the skies
that he retained little privacy or personal security to be lost to
police surveillance. The question before us must be not whether the
police were where they had a right to be, but whether public
observation of Riley's curtilage was so commonplace that Riley's
expectation of privacy in his backyard could not be considered
reasonable. To say that an invasion of Riley's privacy from the
skies was not impossible is most emphatically not the same as
saying that his expectation of privacy within his enclosed
curtilage was not "one that society is prepared to recognize as reasonable.'" Katz, 389 U.S. at 389 U. S. 361 (Harlan, J., concurring). [ Footnote
2/4 ] While, as we held in Ciraolo, air traffic at
elevations of 1,000 feet or more may be so common that whatever
could be seen with the naked eye from that elevation is unprotected
by the Fourth Amendment, it is a large step from there to say that
the Amendment offers no protection against low-level helicopter
surveillance of enclosed curtilage Page 488 U. S. 461 areas. To take this step is error enough. That the plurality
does so with little analysis beyond its determination that the
police complied with FAA regulations is particularly
unfortunate.

															Equally disconcerting is the lack of any meaningful limit to the
plurality's holding. It is worth reiterating that the FAA
regulations the plurality relies on as establishing that the
officer was where he had a right to be set no minimum flight
altitude for helicopters. It is difficult, therefore, to see what,
if any, helicopter surveillance would run afoul of the plurality's
rule that there exists no reasonable expectation of privacy as long
as the helicopter is where it has a right to be.

															Only in its final paragraph does the plurality opinion suggest
that there might be some limits to police helicopter surveillance
beyond those imposed by FAA regulations:

															"Neither is there any intimation here that the helicopter
interfered with respondent's normal use of the greenhouse or of
other parts of the curtilage. As far as this record reveals, no
intimate details connected with the use of the home or curtilage
were observed, and there was no undue noise, and no wind, dust, or
threat of injury. In these circumstances, there was no violation of
the Fourth Amendment." Ante at 488 U. S. 452 .
[ Footnote 2/5 ] I will deal with the
"intimate details" below. For the rest, one wonders what the
plurality believes the purpose of the Fourth Amendment to be. If
through noise, wind, dust, and threat of injury from helicopters
the State "interfered with respondent's normal use of the
greenhouse or of other parts Page 488 U. S. 462 of the curtilage," Riley might have a cause of action in inverse
condemnation, but that is not what the Fourth Amendment is all
about. Nowhere is this better stated than in JUSTICE WHITE's
opinion for the Court in Camara v. Municipal Court, 387 U. S. 523 , 387 U. S. 528 (1967):

															"The basic purpose of this Amendment, as recognized in countless
decisions of this Court, is to safeguard the privacy and security
of individuals against arbitrary invasions by governmental
officials." See also Marshall v. Barlow's, Inc., 436 U.
S. 307 , 436 U. S. 312 (1978) (same); Schmerber v. California, 384 U.
S. 757 , 384 U. S. 767 (1966) ("The overriding function of the Fourth Amendment is to
protect personal privacy and dignity against unwarranted intrusion
by the State"); Wolf v. Colorado, 338 U. S.
25 , 338 U. S. 27 (1949) ("The security of one's privacy against arbitrary intrusion
by the police . . . is at the core of the Fourth Amendment . . ."), overruled on other grounds, Mapp v. Ohio, 367 U.
S. 643 (1961); Boyd v. United States, 116 U. S. 616 , 116 U. S. 630 (1886) ("It is not the breaking of his doors, and the rummaging of
his drawers, that constitutes the essence of the offence; but it is
the invasion of his indefeasible right of personal security. . .
.").

															If indeed the purpose of the restraints imposed by the Fourth
Amendment is to "safeguard the privacy and security of
individuals," then it is puzzling why it should be the helicopter's
noise, wind, and dust that provides the measure of whether this
constitutional safeguard has been infringed. Imagine a helicopter
capable of hovering just above an enclosed courtyard or patio
without generating any noise, wind, or dust at all -- and, for good
measure, without posing any threat of injury. Suppose the police
employed this miraculous tool to discover not only what crops
people were growing in their greenhouses, but also what books they
were reading and who their dinner guests were. Suppose, finally,
that the FAA regulations remained unchanged, so that the police
were undeniably "where they had a right to be." Would today's Page 488 U. S. 463 plurality continue to assert that "[t]he right of the people to
be secure in their persons, houses, papers, and effects, against
unreasonable searches and seizures" was not infringed by such
surveillance? Yet that is the logical consequence of the
plurality's rule that, so long as the police are where they have a
right to be under air traffic regulations, the Fourth Amendment is
offended only if the aerial surveillance interferes with the use of
the backyard as a garden spot. Nor is there anything in the
plurality's opinion to suggest that any different rule would apply
were the police looking from their helicopter, not into the open
curtilage, but through an open window into a room viewable only
from the air. III Perhaps the most remarkable passage in the plurality opinion is
its suggestion that the case might be a different one had any
"intimate details connected with the use of the home or curtilage
[been] observed." Ante at 488 U. S. 452 .
What, one wonders, is meant by "intimate details"? If the police
had observed Riley embracing his wife in the backyard greenhouse,
would we then say that his reasonable expectation of privacy had
been infringed? Where in the Fourth Amendment or in our cases is
there any warrant for imposing a requirement that the activity
observed must be "intimate" in order to be protected by the
Constitution?

															It is difficult to avoid the conclusion that the plurality has
allowed its analysis of Riley's expectation of privacy to be
colored by its distaste for the activity in which he was engaged.
It is indeed easy to forget, especially in view of current concern
over drug trafficking, that the scope of the Fourth Amendment's
protection does not turn on whether the activity disclosed by a
search is illegal or innocuous. But we dismiss this as a "drug
case" only at the peril of our own liberties. Justice Frankfurter
once noted that

															"[i]t is a fair summary of history to say that the safeguards of
liberty have frequently been forged in controversies involving not
very Page 488 U. S. 464 nice people," United States v. Rabinowitz, 339 U. S.
56 , 339 U. S. 69 (1950) (dissenting opinion), and nowhere is this observation more
apt than in the area of the Fourth Amendment, whose words have
necessarily been given meaning largely through decisions
suppressing evidence of criminal activity. The principle enunciated
in this case determines what limits the Fourth Amendment imposes on
aerial surveillance of any person, for any reason. If the
Constitution does not protect Riley's marijuana garden against such
surveillance, it is hard to see how it will forbid the government
from aerial spying on the activities of a law-abiding citizen on
her fully enclosed outdoor patio. As Professor Amsterdam has
eloquently written:

															"The question is not whether you or I must draw the blinds
before we commit a crime. It is whether you and I must discipline
ourselves to draw the blinds every time we enter a room, under pain
of surveillance if we do not."

															Amsterdam, 58 Minn.L.Rev. at 403. [ Footnote 2/6 ] IV I find little to disagree with in the concurring opinion of
JUSTICE O'CONNOR, apart from its closing paragraphs. A majority of
the Court thus agrees that the fundamental inquiry is not whether
the police were where they had a right to be under FAA regulations,
but rather whether Riley's expectation of privacy was rendered
illusory by the extent of Page 488 U. S. 465 public observation of his backyard from aerial traffic at 400
feet.

															What separates me from JUSTICE O'CONNOR is essentially an
empirical matter concerning the extent of public use of the
airspace at that altitude, together with the question of how to
resolve that issue. I do not think the constitutional claim should
fail simply because "there is reason to believe" that there is
"considerable" public flying this close to earth or because Riley
"introduced no evidence to the contrary before the Florida courts." Ante at 488 U. S. 455 (O'CONNOR, J., concurring in judgment). I should think that this
might be an apt occasion for the application of Professor Davis'
distinction between "adjudicative" and "legislative" facts. See Davis, An Approach to Problems of Evidence in the
Administrative Process, 55 Harv.L.Rev. 364, 402-410 (1942); see
also Advisory Committee's Notes on Fed.Rule Evid. 201, 28
U.S.C.App. pp. 683-684. If so, I think we could take judicial
notice that, while there may be an occasional privately owned
helicopter that flies over populated areas at an altitude of 400
feet, such flights are a rarity, and are almost entirely limited to
approaching or leaving airports or to reporting traffic congestion
near major roadways. And, as the concurrence agrees, ante at 488 U. S. 455 ,
the extent of police surveillance traffic cannot serve as a
bootstrap to demonstrate public use of the airspace.

															If, however, we are to resolve the issue by considering whether
the appropriate party carried its burden of proof, I again think
that Riley must prevail. Because the State has greater access to
information concerning customary flight patterns, and because the
coercive power of the State ought not be brought to bear in cases
in which it is unclear whether the prosecution is a product of an
unconstitutional, warrantless search, cf. Bumper v. North
Carolina, 391 U. S. 543 , 391 U. S. 548 (1968) (prosecutor has burden of proving consent to search), the
burden of proof properly rests with the State, and Page 488 U. S. 466 not with the individual defendant. The State quite clearly has
not carried this burden. [ Footnote
2/7 ] V The issue in this case is, ultimately, "how tightly the fourth
amendment permits people to be driven back into the recesses of
their lives by the risk of surveillance." Amsterdam, supra, at 402. The Court today approves warrantless
helicopter surveillance from an altitude of 400 feet. While JUSTICE
O'CONNOR's opinion gives reason to hope that this altitude may
constitute a lower limit, I find considerable cause for concern in
the fact that a plurality of four Justices would remove virtually
all constitutional barriers to police surveillance from the vantage
point of helicopters. The Fourth Amendment demands that we temper
our efforts to apprehend criminals with a concern for the impact on
our fundamental liberties of the methods we use. I hope it will be
a matter of concern to my colleagues that the police surveillance
methods they would sanction were among those described forty years
ago in George Orwell's dread vision of life in the 1980's:

															"The black-mustachio'd face gazed down from every commanding
corner. There was one on the house front immediately opposite. BIG
BROTHER IS WATCHING YOU, the caption said. . . . In the far
distance, a helicopter skimmed down between the roofs, hovered for
an instant like a bluebottle, and darted away again with a curving
flight. It was the Police Patrol, snooping into people's
windows."

															G. Orwell, Nineteen Eighty-Four 4 (1949) Page 488 U. S. 467 Who can read this passage without a shudder, and without the
instinctive reaction that it depicts life in some country other
than ours? I respectfully dissent.

															[ Footnote 2/1 ]

															What the plurality now states as a firm rule of Fourth Amendment
jurisprudence appeared in Ciraolo, 476 U.S. at 476 U. S. 213 ,
as a passing comment:

															"Nor does the mere fact that an individual has taken measures to
restrict some views of his activities preclude an officer's
observations from a public vantage point where he has a right to be
and which renders the activities clearly visible. E.g., United
States v. Knotts, 460 U. S. 276 , 460 U. S.
282 (1983)."

															This rule for determining the constitutionality of aerial
surveillance thus derives ultimately from Knotts, a case
in which the police officers' feet were firmly planted on the
ground. What is remarkable is not that one case builds on another,
of course, but rather that a principle based on terrestrial
observation was applied to airborne surveillance without any
consideration whether that made a difference.

															[ Footnote 2/2 ]

															The plurality's use of the FAA regulations as a means for
determining whether Riley enjoyed a reasonable expectation of
privacy produces an incredible result. Fixed-wing aircraft may not
be operated below 500 feet (1,000 feet over congested areas), while
helicopters may be operated below those levels. See ante at 488 U. S. 451 ,
n. 3. Therefore, whether Riley's expectation of privacy is
reasonable turns on whether the police officer at 400 feet above
his curtilage is seated in an airplane or a helicopter. This cannot
be the law.

															[ Footnote 2/3 ]

															In Oliver v. United States, 466 U.
S. 170 (1984), for example, we held that police officers
who trespassed upon posted and fenced private land did not violate
the Fourth Amendment, despite the fact that their action was
subject to criminal sanctions. We noted that the interests
vindicated by the Fourth Amendment were not identical with those
served by the common law of trespass. See id. at 466 U. S.
183 -184, and n. 15; see also Nester v. United
States, 265 U. S. 57 (1924)
(trespass in "open fields" does not violate the Fourth Amendment).
In Olmstead v. United States, 277 U.
S. 438 , 277 U. S.
466 -469 (1928), the illegality under state law of a
wiretap that yielded the disputed evidence was deemed irrelevant to
its admissibility. And of course Katz v. United States, 389 U. S. 347 (1967), which overruled Olmstead, made plain that the
question whether or not the disputed evidence had been procured by
means of a trespass was irrelevant. Recently, in Dow Chemical
Co. v. United States, 476 U. S. 227 , 476 U. S. 239 ,
n. 6 (1986), we declined to consider trade secret laws indicative
of a reasonable expectation of privacy. Our precedent thus points
not toward the position adopted by the plurality opinion, but
rather toward the view on this matter expressed some years ago by
the Oregon Court of Appeals:

															"We . . . find little attraction in the idea of using FAA
regulations, because they were not formulated for the purpose of
defining the reasonableness of citizens' expectations of privacy.
They were designed to promote air safety." State v. Davis, 51 Ore.App. 827, 831, 627 P.2d
492 , 494 (1981).

															[ Footnote 2/4 ] Cf. California v. Greenwood, 486 U. S.
35 , 486 U. S. 64 (1988) (BRENNAN, J., dissenting) ("The mere possibility that unwelcome meddlers might open and rummage through the
containers does not negate the expectation of privacy in their
contents. . . .").

															[ Footnote 2/5 ]

															Without actually stating that it makes any difference, the
plurality also notes that "there is nothing in the record or before
us to suggest" that helicopter traffic at the 400-foot level is so
rare as to justify Riley's expectation of privacy. Ante at 488 U. S. 451 .
The absence of anything "in the record or before us" to suggest the
opposite, however, seems not to give the plurality pause. It
appears, therefore, that it is the FAA regulation, rather than any
empirical inquiry, that is determinative.

															[ Footnote 2/6 ] See also United States v. White, 401 U.
S. 745 , 401 U. S.
789 -790 (1971) (Harlan, J., dissenting):

															"By casting its 'risk analysis' solely in terms of the
expectations and risks that 'wrongdoers' or 'one contemplating
illegal activities' ought to bear, the plurality opinion, I think,
misses the mark entirely. . . . The interest [protected by the
Fourth Amendment] is the expectation of the ordinary citizen, who
has never engaged in illegal conduct in his life, that he may carry
on his private discourse freely, openly, and spontaneously. . . .
Interposition of a warrant requirement is designed not to shield
'wrongdoers,' but to secure a measure of privacy and a sense of
personal security throughout our society."

															[ Footnote 2/7 ]

															The issue in Jones v. United States, 362 U.
S. 257 , 362 U. S. 261 (1960), cited by JUSTICE O'CONNOR, was whether the defendant had
standing to raise a Fourth Amendment challenge. While I would agree
that the burden of alleging and proving facts necessary to show
standing could ordinarily be placed on the defendant, I fail to see
how that determination has any relevance to the question of where
the burden should lie on the merits of the Fourth Amendment
claim.

															JUSTICE BLACKMUN, dissenting.

															The question before the Court is whether the helicopter
surveillance over Riley's property constituted a "search" within
the meaning of the Fourth Amendment. Like JUSTICE BRENNAN, JUSTICE
MARSHALL, JUSTICE STEVENS, and JUSTICE O'CONNOR, I believe that
answering this question depends upon whether Riley has a
"reasonable expectation of privacy" that no such surveillance would
occur, and does not depend upon the fact that the helicopter was
flying at a lawful altitude under FAA regulations. A majority of
this Court thus agrees to at least this much.

															The inquiry then becomes how to determine whether Riley's
expectation was a reasonable one. JUSTICE BRENNAN, the two Justices
who have joined him, and JUSTICE O'CONNOR all believe that the
reasonableness of Riley's expectation depends, in large measure, on
the frequency of nonpolice helicopter flights at an altitude of 400
feet. Again, I agree.

															How is this factual issue to be decided? JUSTICE BRENNAN
suggests that we may resolve it ourselves without any evidence in
the record on this point. I am wary of this approach. While I, too,
suspect that, for most American communities, it is a rare event
when nonpolice helicopters fly over one's curtilage at an altitude
of 400 feet, I am not convinced that we should establish a per
se rule for the entire Nation based on judicial suspicion
alone. See Coffin, Judicial Balancing, 63 N.Y.U.L.Rev. 16,
37 (1988).

															But we need not abandon our judicial intuition entirely. The
opinions of both JUSTICE BRENNAN and JUSTICE O'CONNOR, by their use
of "cf." citations, implicitly recognize that none of our prior
decisions tells us who has the burden of proving whether Riley's
expectation of privacy was reasonable. In the absence of precedent
on the point, it is appropriate for us to take into account our
estimation of the Page 488 U. S. 468 frequency of nonpolice helicopter flights. See 4 W.
LaFave, Search and Seizure § 11.2(b), p. 228 (2d ed.1987) (burdens
of proof relevant to Fourth Amendment issues may be based on a
judicial estimate of the probabilities involved). Thus, because I
believe that private helicopters rarely fly over curtilages at an
altitude of 400 feet, I would impose upon the prosecution the
burden of proving contrary facts necessary to show that Riley
lacked a reasonable expectation of privacy. Indeed, I would
establish this burden of proof for any helicopter surveillance case
in which the flight occurred below 1,000 feet -- in other words,
for any aerial surveillance case not governed by the Court's
decision in California v. Ciraolo, 476 U.
S. 207 (1986).

															In this case, the prosecution did not meet this burden of proof,
as JUSTICE BRENNAN notes. This failure should compel a finding that
a Fourth Amendment search occurred. But because our prior cases
gave the parties little guidance on the burden of proof issue, I
would remand this case to allow the prosecution an opportunity to
meet this burden.

															The order of this Court, however, is not to remand the case in
this manner. Rather, because JUSTICE O'CONNOR would impose the
burden of proof on Riley, and because she would not allow Riley an
opportunity to meet this burden, she joins the plurality's view
that no Fourth Amendment search occurred. The judgment of the
Court, therefore, is to reverse outright on the Fourth Amendment
issue. Accordingly, for the reasons set forth above, I respectfully
dissent.

Summary: In Florida v. Riley, the Supreme Court held that police observation of a greenhouse from a helicopter at 400 feet, which revealed marijuana plants, did not constitute a Fourth Amendment search, as the contents of the greenhouse were visible to the naked eye and the helicopter was within public airspace. The Court reversed the Florida Supreme Court's decision, which had found the helicopter surveillance to be a search requiring a warrant.