Opinion
GRODIN, J. We recently concluded that, unless a warrant is obtained, our state Constitution forbids intensive aerial inspection of an individual enclosed backyard based on prior suspicions that marijuana cultivation will be found within the enclosure. (People v. Cook (1985) 41 Cal.3d 373 [221 Cal.Rptr. 499, 710 P.2d 299].)1 In this case, we confront a different type of police activity. Under a program designed to curb widespread commercial marijuana farming in rural and semirural areas, law enforcement officials took to the air, in fixed-wing aircraft, to identify the locations of marijuana crops being grown in open fields. Flying at elevations from which the details of human activity could not be observed, they saw indications of what they believed to be marijuana growing in a remote area. While there were signs of human habitation nearby, and the officers took photographs to show the relationship between that habitation and the growing crop, it was the crop in the open field, and not defendant’s residence or curtilage, [1308]that was the principal focus of their attention. Under these circumstances we will conclude that defendant had no reasonable expectation that his land would be immune from such limited aerial surveillance, and that the surveillance was permissible under the United States and California Constitutions.
While we uphold the instant search on its facts, we recognize that a random surveillance and eradication program presents difficult constitutional and regulatory problems. Certain practices of the program operating in defendant’s locale have already led to a successful class injunction suit. We invite the Legislature to participate in establishing standards which will balance the needs of law enforcement against the legitimate privacy expectations of affected citizens.
Facts
Aerial surveillance by the police revealed what they suspected were marijuana gardens growing on appellant Mayoff’s land. Based on the aerial views, the police obtained a warrant for a ground search of the property. Under its authority, they seized a portion of appellant’s marijuana crop. He was charged with one count of cultivation of marijuana. (Health & Saf. Code, § 11358.) He moved to set aside the information and suppress the evidence against him (Pen. Code, §§ 995, 1538.5), urging that the aerial surveillance of his property violated his constitutional rights of privacy, and against unreasonable searches and seizures. (U.S. Const., Amend. IV; Cal. Const., art. I, §§ 1, 13.) The trial court denied appellant’s motions after a hearing, and he entered a plea of guilty. He was sentenced to six months in county jail and two years’ probation. He now appeals, solely on the constitutional grounds rejected below.
The surveillance which led to discovery of appellant’s crop was part of a program operated in several rural northern California counties where widespread commercial marijuana farming has taken root. The program is run jointly by local, state, and federal law enforcement personnel; it has been in effect in Humboldt County, where appellant resides, for approximately eight years. Fundamental to the scheme is a random pattern of warrantless flights over the entire county, focusing on rural areas. The flights are undertaken for the purpose of identifying plots of land on which it appears marijuana is being cultivated.2 The viewing officers note such factors as the [1309]color and spacing of plants, their relationship to nearby structures, signs of cultivation, and the location and general characteristics of the terrain under scrutiny. The vast majority of flights are made without prior information about the existence of marijuana at a particular location. The areas surveyed during a particular flight are selected almost entirely at random. “There is no exact pattern,” one of the participating officers said at a preliminary hearing. “I mean, I just fly wherever I feel like flying. ... No set pattern.” During each flight, the viewing officer is “looking constantly” at the ground below.
Much of Humboldt County’s terrain is extremely rugged and isolated. Appellant, like roughly one-tenth of the county’s rural population of about 29,000, lives in territory so remote that it can be examined only from the air. His 40-acre parcel is in a mountainous, wooded region, almost a mile from the nearest paved road. It cannot be seen from the road, and is connected to it by a dirt path which winds its way toward the portion of the property on which appellant resides. Only the top of one of appellant’s buildings is visible from the path, which abruptly ends shortly after connecting with a turnoff to his residence. This turnoff is so rocky it is difficult to traverse without benefit of a four-wheel-drive vehicle.
On July 23, 1980, Agent Brown of the California Department of Justice and Detective Vulich of the Humboldt County Sheriff’s Department made an antimarijuana surveillance flight from Eureka to the Garberville area in southern Humboldt County. They had no search warrant and no prior suspicion marijuana was being grown on appellant’s property. From an altitude of at least 1,000 feet, one of the officers noticed what he believed to be marijuana growing on appellant’s land.
Nearly two weeks later, on August 4, 1980, Detective Vulich flew again over appellant’s property in order to photograph the land below. Again, it appears that an altitude between 1,000 and 2,000 feet was maintained. Vulich still had no search warrant. Apparently using an 80-200 millimeter telephoto lens, he photographed the suspicious vegetation, two trailers parked on the property, and the surrounding area. On his return to police headquarters he showed the snapshots to Agent Brown, who then executed an affidavit in support of a search warrant. On August 15, 1980, the warrant [1310]was served, and marijuana was in fact discovered on appellant’s property, in two separate gardens and in one of the inhabited trailers. At least one garden was fenced, and both were surrounded by steep slopes and wilderness. There was no public vantage point on land from which the gardens or the trailers could be seen.
The aerial photographs introduced in evidence indicate that the gardens were at least 200 feet from the closest of the trailers. No fences formed a common enclosure around the trailers and the garden area.
Discussion
1. Warrantless aerial surveillance.
In California, the legality of a warrantless police intrusion into allegedly private zones of activity depends on whether the government has “unreasonably” invaded an actual expectation of privacy which society is prepared to recognize as reasonable. (E.g., Cook, supra, 41 Cal.3d at p. 379; Lorenzana v. Superior Court (1973) 9 Cal.3d 626, 638 [108 Cal.Rptr. 585, 511 P.2d 33]; see Katz v. United States (1967) 389 U.S. 347, 350-352 [19 L.Ed.2d 576, 581-583, 88 S.Ct. 507].) All parties concede that defendant sought privacy for his residence and his marijuana gardens. They were on his private property in a remote area, away from ground-level vantage points open to the public. The gardens themselves, while not immediately adjacent to the residential structures, were carefully enclosed by fences and trees. The only issues, therefore, are whether defendant’s wishes were objectively reasonable and, if so, whether the warrantless aerial observation invaded his expectations unreasonably.
Three recent cases bear on these questions but do not resolve them. The first such decision is United States v. Oliver (1984) 466 U.S. 170 [80 L.Ed.2d 214, 104 S.Ct. 1735]. In two separate incidents there under review, law enforcement agents, acting without warrants or probable cause, entered remote rural private property to look for marijuana cultivation. Noting that the land inspected in each instance was some distance from any home or business, the high court found no violation of the Fourth Amendment.
The Oliver majority conceded that the Fourth Amendment provides a high degree of privacy protection to the “curtilage” of a residence—“the land immediately surrounding and associated with the home.” (P. 180 [80 L.Ed.2d p. 225].) However, it affirmed the long-standing rule (see Hester v. United States (1924) 265 U.S. 57 [68 L.Ed. 898, 44 S.Ct. 445]) that the federal Constitution allows the authorities to inspect areas beyond the curtilage—so-called “open fields”—at will, even where they trespass on private [1311]property which was clearly intended to be shielded from the view of outsiders. (Pp. 176-184 [80 L.Ed.2d pp. 222-228].)
The five majority justices concluded that open fields are not among the “persons, houses, papers, and effects” described in the Fourth Amendment. (Pp. 176-177 [80 L.Ed.2d p. 223]; see Hester, supra, 265 U.S. at p. 59 [68 L.Ed. at p. 900].) Moreover, the Oliver majority reasoned, society is not prepared to recognize such areas as protected zones of intimate privacy, even where the individuals who seek privacy in such places have made that intention clear. (466 U.S. at pp. 179-184 [80 L.Ed.2d at pp. 224-228].)3 Under Oliver, police observation of an open field, at least from the ground, simply is not a “search” subject to federal constitutional limitations.4
In Cook, supra, we subsequently confirmed that the California Constitution, like its federal counterpart, protects with special zeal the legitimate expectation of privacy within a residential curtilage. Law enforcement agents may not defeat that expectation, we ruled, by spying at will on a private yard from an aircraft.
We were not persuaded that police officers who examine a residence from the air are simply observing what is in “plain view” from a lawful public vantage point. Such reasoning, we explained, ignores the essential difference between ground and aerial surveillance. One can take reasonable steps to ensure his yard’s privacy from the street, sidewalk, or neighborhood, and police on the ground may not broach such barriers to gain a view of the enclosed area. But there is no practical defense against aerial spying, and precious constitutional privacy rights would mean little if the government could defeat them so easily.
Even if members of the public may casually see into his yard when a routine flight happens over the property, we concluded, a householder does not thereby consent to focused examination of the curtilage by airborne police officers looking for evidence of crime. No law enforcement interest justifies such intensive warrantless government intrusion into a zone of heightened constitutional privacy. (41 Cal.3d at pp. 379-385.)
[1312]Cook was decided exclusively under the California Constitution. A more recent United States Supreme Court decision, California v. Ciraolo, supra, — U.S. — [90 L.Ed.2d 210], has ruled that warrantless aerial surveillance of the curtilage does not contravene the Fourth Amendment.
In Ciraolo, as in Cook, one convicted on a marijuana charge urged that the police violated his constitutional rights when they examined his enclosed backyard from an airplane to confirm vague suspicions that he was engaged in illegal cultivation. Over a vigorous dissent, a bare majority of the high court disagreed. However private the curtilage in other contexts, the majority said, the realities of air travel force a modern householder to assume that his yard and anything in it are in plain view from the air. (— U.S. at pp. — — [90 L.Ed.2d at pp. 215-218] [see also dis. opn. by Powell, J., at p. — et seq. (90 L.Ed.2d at p. 218 et seq.)]; cf., Dow Chemical Co. v. United States (1986) — U.S. — [90 L.Ed.2d 226, 235-238, — S.Ct. —].)
Our state charter is a “document of independent force” (People v. Brisendine (1975) 13 Cal.3d 528, 549-550 [119 Cal.Rptr. 315, 531 P.2d 1099]), and its guarantees “are not dependent on those [provided] by the United States Constitution” unless a contrary intent appears. (Cal. Const., art. I, § 24.) We grant “respectful consideration” to constitutional interpretations of the United States Supreme Court, but they are to be followed in California “only where they provide no less individual protection than is guaranteed by California law.” (People v. Longwill (1975) 14 Cal.3d 943, 951, fn. 4 [123 Cal.Rptr. 297, 538 P.2d 753].) On many occasions, we have concluded that the California Constitution accords greater protection to individual rights within our borders than federal law guarantees throughout the nation. (E.g., People v. Bustamonte (1981) 30 Cal.3d 88, 102 [177 Cal.Rptr. 576, 634 P.2d 927]; People v. Pettingill (1978) 21 Cal.3d 231, 246-252 [145 Cal.Rptr. 861, 578 P.2d 108]; People v. Disbrow (1976) 16 Cal.3d 101, 113 [127 Cal.Rptr. 360, 545 P.2d 272].)
Having carefully examined the majority decisions in Ciraolo and Dow Chemical, cited supra, we find ourselves unconvinced by their reasoning. We adhere to our holding in Cook. The question remains whether the federal and state Constitutions nonetheless permit the “random” rural aerial surveillance at issue in this case.
Before Oliver was decided, California courts displayed some uncertainty about whether the “open fields” doctrine had survived the intervening principle of Katz, supra, that “the [Constitution] protects people, not places” and may shield “what [a person] seeks to preserve as private, even in an area accessible to the public . . . .” (389 U.S. at p. 350 [19 L.Ed.2d at p. 582]; compare, e.g., People v. Krivda (1971) 5 Cal.3d 357, 364-365 [1313][96 Cal.Rptr. 62, 486 P.2d 1262] [what person seeks to preserve as private, even in public area, may be constitutionally protected]; People v. Edwards (1969) 71 Cal.2d 1096, 1101 [80 Cal.Rptr. 633, 458 P.2d 713] [whether place such as “open field” is or is not “constitutionally protected area” does not necessarily determine reasonable expectation of privacy]; Burkholder v. Superior Court (1979) 96 Cal. App.3d 421, 425-430 [158 Cal.Rptr. 86] [secluded “open field” on private property protected from ground, but not air, inspection]; and Phelan v. Superior Court (1979) 90 Cal.App.3d 1005, 1011 [153 Cal.Rptr. 738] [expectation of privacy in remote rural marijuana garden is reasonable if desire for privacy is exhibited] with People v. Dumas (1973) 9 Cal.3d 871, 881-882, fn. 9 [109 Cal.Rptr. 304, 512 P.2d 1208] [“open fields” are among places so public that search is justified without warrant or exigency]; People v. Scheib (1979) 98 Cal.App.3d 820, 826-827 [159 Cal.Rptr. 665] [citing Dumas]; and People v. Ketchum (1975) 45 Cal.App.3d 328, 330 [119 Cal.Rptr. 368] [same].)
However, pre-Oliver California cases consistently upheld warrantless surveillance of rural marijuana gardens from airplanes flying at normal altitudes, even when surveillance was part of a “random” overflight program, employed optical aids, and inspected homes or human activities near the gardens. Interpreting Katz in a manner which anticipated Oliver, the Courts of Appeal reasoned that common habits in the use of agricultural and woodland property preclude any reasonable expectation that crops growing there will not be seen from legal aerial vantage points by the public or the police. (Dean v. Superior Court (1973) 35 Cal.App.3d 112, 114, 117 [110 Cal.Rptr. 585] [patch located “in an isolated area of the Sierra foothills, . . . hidden from view by the surrounding hills and woods”]; see also People v. Egan (1983) 141 Cal.App.3d 798, 800, 806 [190 Cal.Rptr. 546] [overflight of ranch prompted by rumors of marijuana cultivation; “[t]he appellate courts of this state have consistently upheld aerial surveillance from lawful altitudes over rural and relatively unpopulated property. . . .”]; Tuttle v. Superior Court (1981) 120 Cal.App.3d 320, 327 [174 Cal.Rptr. 576], cert, den., 454 U.S. 1033 [70 L.Ed.2d 477, 102 S.Ct. 571] [“Tents, ‘other structures,’ vehicles, and people . . . observed” near rural garden area; trails led from structures to garden]; People v. Joubert (1981) 118 Cal.App.3d 637, 640-641 [173 Cal.Rptr. 428] [binoculars used; “outbuildings resembling barns [and a] ‘predominant house’” observed within 29-acre parcel; house was “focus of particular attention” by observers]; People v. St. Amour (1980) 104 Cal.App.3d 886, 889-893 [163 Cal.Rptr. 187] [Humboldt County random surveillance program; plants seen “on a mountain slope in a deserted area” a mile and a half from nearest town; though “no business or other human activities were observable,” the site included a tent]; Burkholder, supra, 96 Cal.App.3d at pp. 423-425 [Santa Cruz County random surveil[1314]lance program; binoculars and telephoto camera used; garden observed “in a heavily wooded, mountainous area”].)
Courts in other jurisdictions have applied similar principles to uphold, under a wide variety of circumstances, warrantless aerial surveillance for marijuana in rural areas. (United States v. Allen (9th Cir. 1980) 675 F.2d 1373, 1380-1381, cert. den. (1981) 454 U.S. 833 [70 L.Ed.2d 112, 102 S.Ct. 133] [helicopter surveillance with binoculars and telephoto lenses; seacoast ranch routinely traversed by Coast Guard helicopters for law enforcement purposes; prior site-specific suspicion of drug smuggling]; United States v. DeBacker (W.D.Mich. 1980) 493 F.Supp. 1078, 1081 [“isolated” episodes of surveillance over farm in “boondocks” at altitudes as low as 50 feet and distances as near as 40 feet to one of working farmhands; public overflights at low altitudes “not uncommon”]; Diehl v. State (Fla.App. 1984) 461 So.2d 157, 158 [no reasonable expectation of privacy from aerial observation of “open field” (citing Oliver)]; State v. Bigler (1983) 100 N.M. 515 [673 P.2d 140, 141] [unaided aerial view of cornfield containing marijuana; no reasonable expectation of privacy from airplanes; municipal airport nearby and low-altitude cropduster flights common]; State v. Stachler (1981) 58 Hawaii 412 [570 P.2d 1323, 1325-1329] [random surveillance; binocular-aided helicopter view of marijuana patch 15 feet from house on remote and secluded 4-acre parcel; helicopter’s maintenance of legal altitude (300 feet) and frequency of overflights by other aircraft contribute to finding of no reasonable privacy expectation]; State v. Davis (1981) 51 Ore.App. 827 [627 P.2d 492, 493-494] [airplane flying at 600-700 feet observed marijuana patch 150-300 feet from dwellings on defendant’s locked, posted, and secluded land in somewhat populated area; no reasonable expectation of privacy even though aircraft’s altitude violated F.A.A. regulations]; State v. Layne (Tenn.Crim.App. 1981) 623 S.W.2d 629, 632-636 [helicopter surveillance of rural field containing 5 persons from altitude of 1,800 feet; marijuana observed by police from legal aerial vantage point is in “open view”]; see People v. Lashmett (1979) 71 Ill.App.3d 429 [27 Ill.Dec. 657, 389 N.E.2d 888, 890-894], cert. den. (1980) 444 U.S. 1081 [62 L.Ed.2d 765, 100 S.Ct. 1034] [observation of stolen tractor from legal height of 2,400 feet; rural field away from house and curtilage; “open field” doctrine applies].)
For state as well as federal purposes, we accept Oliver’s premise that there is a greater legitimate expectation of privacy within the home and curtilage than in “open fields.” We agree that the “curtilage,” under both the state and federal Constitutions, is confined to those outdoor areas “immediately adjacent to the home” to which extend “the intimate activity associated with the ‘sanctity of a [person’s] home and the privacies of life’ [citation omitted] . . .”; outdoor places beyond this adjacent and intimate [1315]zone are “open fields.” (Oliver, supra, 466 U.S. at p. 180 [80 L.Ed.2d at p. 225]; see also p. 182, fn. 12 [80 L.Ed.2d at p. 226].)
Moreover, we conclude, as prior cases have suggested, that there can be no reasonable expectation of absolute privacy from warrantless aerial surveillance by the police of crops growing in open fields. Insofar as the open fields are observed from sufficient altitude to prevent disruption or detailed observation of individual activities below, the fields are in “plain view” from the air, and aerial surveillance for illegal cultivation there is not a “search” governed by either Constitution.5
In our view, the crop at issue here lay outside the curtilage, in an open field. We recognize that some decisions have defined rural curtilages expansively. Yet we are not persuaded that the cultivation which drew the officers’ attention here was within a zone of heightened privacy.
The suspicious vegetation was seen in a secluded, mountainous area, some 200 or more feet from trailers which might be residences. While the cultivated area was shielded from ground-level vantage points outside appellant’s property, it was not in an area “immediately adjacent” to the trailers “to which . . . the intimate activity associated with the ‘sanctity of a man’s home and the privacies of life’ ” could be expected to extend. There was no physical indication, such as a common enclosure, that the trailers and gardens were considered a common zone of private residential activity.
Appellant urges that, even if his crop was therefore in an open field, the officers’ simultaneous scrutiny of his house and curtilage was an invalid warrantless search. That impropriety, appellant asserts, requires suppression of the marijuana discovery. For several reasons, we cannot accept this premise.
The surveying officers admitted that they did not avert their eyes from the terrain surrounding the suspicious cultivation, and the aerial photos presented to the magistrate depict not only the garden itself, but the nearby trailers, hillsides, trails, and roads. One officer conceded he unavoidably [1316]examined the apparently inhabited zone, since “the eye did encompass quite a bit.”
It is clear, however, that the focus of the examination for criminal activity was the cultivated area outside the curtilage. The officers saw nothing criminal within the curtilage, and it appears that their primary interest in noticing this area was to establish its relationship, if any, to the outlying crops. The observations took place from over 1,000 feet above defendant’s property. The officers testified that the photographs presented to the magistrate, though some may have been taken with telephoto equipment, accurately show the scale of objects as they appeared to the naked eye.6 If that is so, the details of human activity could scarcely have been discernible from the aircraft. All the photographs reveal is evidence that inhabited structures exist in the vicinity, and that they may be related to cultivation in open fields. The most casual passing airplane could see as much.
We think that observation of crops growing in open fields is not transformed into an unconstitutional search when the officers incidentally and unavoidably observe the existence of a nearby home and curtilage, and its relationship to the fields, from a visual altitude at which the possibility of intrusion on private activities below is remote.7
Our holding here is distinguishable from that of Cook, supra. There we prohibited all warrantless aerial scrutiny of a residential curtilage for the particular purpose of confirming a suspicion that criminal activity is taking place there. There is a difference, significant for constitutional purposes, between surveillance focused on a particular residential yard, on [1317]the one hand, and, on the other, surveillance which concentrates on open fields and merely notices their relationship to nearby habitation. In the former case, represented by Cook, there is no independent justification for the overflight; in the latter, the open fields doctrine provides an initial justification for the officers’ airborne presence. Moreover, in the Cook situation, the intensity and focused nature of the observation, even if it occurs from substantial altitudes, enhances the danger that innocent activities occurring within a legitimate zone of protected privacy will be unreasonably infringed.
Finally, we cannot ignore the differing law enforcement interests involved. The inquiry whether particular privacy expectations are “reasonable,” and whether government has intruded upon them “unreasonably,” involves a weighing of the competing privacy and law enforcement interests. (See, e.g., New Jersey v. T.L.O. (1985) 469 U.S. 325, 336 [83 L.Ed.2d 720, 731, 105 S.Ct. 733] and conc. opn. of Blackmun, J., at 469 U.S. at p. 351 [83 L.Ed.2d at p. 741]; United States v. Martinez-Fuente (1976) 428 U.S. 543, 560-567 [49 L.Ed.2d 1116, 1129-1134, 96 S.Ct. 3074]; United States v. Brignoni-Ponce (1974) 422 U.S. 873, 883-884 [45 L.Ed.2d 607, 617-618, 95 S.Ct. 2574]; Terry v. Ohio (1968) 392 U.S. 1, 21 [20 L.Ed.2d 889, 905-906, 88 S.Ct. 1868]; People v. Scott (1978) 21 Cal.3d 284, 292-293 [145 Cal.Rptr. 876, 578 P.2d 123].)
The People advise, and appellant does not dispute, that Humboldt County’s random surveillance program was prompted by the rise of a large-scale illegal marijuana cultivation industry in remote areas of the county. There have been serious consequences, the People suggest, for the safety of law-abiding residents and visitors. Precisely in order to avoid discovery, the growers have retreated to places where detection from the ground is difficult or impossible. Persons who do approach a cultivated plot face the prospect of armed resistance. (See fn. 1, ante.) Secure in their weapon-enforced privacy, the farmers pursue their illicit trade unhindered.
Aerial surveillance of these remote, inaccessible, and dangerous areas may be the only feasible means of confronting this extraordinary law enforcement problem. Aerial surveillance also seems the least intrusive way of doing so, since it does not physically impinge at close range upon persons or private premises. (See discussion, ante.)
In our view, mere suspicion that marijuana is growing in the enclosed backyard of a single residence can never justify a warrantless aerial invasion of the enclosure. On the other hand, we do not believe that airborne police officers infringe “unreasonably” on legitimate privacy in homes and curtilages by merely observing the configuration of nearby structures while patrolling open fields for large-scale marijuana cultivation. We conclude [1318]that the surveillance here at issue did not violate appellant’s constitutional rights.8
In so holding on these facts, we do not minimize the difficulties involved in keeping a random surveillance program of this kind within proper bounds. At the behest of irate citizens, a United States District Court has already enjoined certain overreaching surveillance practices of the Humboldt County program. (Nat. Org. for Reform of Marijuana Laws v. Mullen (N.D.Cal. 1985) 608 F.Supp. 945.) In the wake of Proposition 8, such civil actions may prove the most effective bulwark against violations of the state Constitution by agents of law enforcement.9 A principal advantage of this form of enforcement is that all parties will have a full opportunity to present facts bearing on the constitutional reasonableness of a particular surveillance program.
Perhaps the most significant protection for the privacy interest of innocent citizens would be the development of regulatory standards which prescribe and limit the manner in which overflights may be conducted. Such standards would have multiple advantages: they would, among other things, provide law enforcement personnel with a clear guide to the exercise of their discretion; serve as a basis for internal discipline in the event of violation; and [1319]establish a foundation for meaningful judicial review. Most of all, publicly announced standards would reassure householders who seek legitimate privacy in their homes and yards, thus promoting that peace of mind which is an important ingredient of ordered liberty. (See Amsterdam, Perspectives on the Fourth Amendment (1974) 58 Minn.L.Rev. 349, 416 et seq.; Mertens, The Fourth Amendment and the Control of Police Discretion (1984) 17 U. Mich. J.L. Ref. 551, 553-563.) Such standards may of course be established by the Legislature, but we encourage the law enforcement agencies responsible for marijuana surveillance overflights to adopt them as administrative regulations in the first instance. (Cf., Camara v. Municipal Court (1967) 387 U.S. 523, 538 [18 L.Ed.2d 930, 940-941, 87 S.Ct. 1727].) Indeed, in the event of a civil lawsuit aimed at curbing abuse (see discussion, ante), the existence or nonexistence of such standards may be considered an important factor in determining the appropriateness of injunctive relief. (See, e.g., Stark v. Perpich (D.Minn. 1984) 590 F.Supp. 1057 [injunction against drunk driving survey checkpoint denied where promulgation of standards minimized police discretion]; Note, Curbing the Drunk Driver Under the Fourth Amendment: The Constitutionality of Roadblock Seizures (1983) 71 Geo. L.J. 1457.)
2. Aerial identification of marijuana plants.
Appellant urges that probable cause for issuance of the warrant was not established, since it is impossible to identify marijuana plants from altitudes of 1,000 feet and above. Both Agent Brown, who was the warrant affiant, and Detective Vulich testified that their opinions arose from the evidence of cultivation—that the suspected plants were lusher green than the surrounding vegetation, spaced evenly and established in orderly rows in an area of “disturbed” earth. Moreover, the officers noted, the plants were within an enclosed area some distance from the structures on the property and connected to the structures by footpaths. Both officers admitted they could not distinguish the individual shapes or characteristics of the plants.
At the preliminary hearing, a botanist, Dr. Norris, testified that marijuana has no unique color which distinguishes it from other cultivated crops.10 It is impossible, said Dr. Norris, to determine from 1,000 feet the identity of common plants under cultivation.
[1320]However, the officers were permitted to use their experience in marijuana detection,11 and their common sense, to form their opinions. Both emphasized that it was a combination of factors which aroused their suspicions. Agent Brown noted, for example, that the distance from the gardens to the trailer structures was a common pattern for marijuana in particular. The multiple well-worn footpaths connecting the structures to the garden suggested intense activity in the relatively small cultivation area. Moreover, the size and spacing of the plants, the remoteness and ruggedness of the terrain, the temporary look of the structures on the property, and the prevalence of marijuana cultivation in just such settings, all could contribute to a strong inference that this was the crop growing on appellant’s land. The superior court’s resolution of any factual dispute over ability to identify was thus substantially supported, and we cannot disturb it. (People v. Leyba (1981) 29 Cal.3d 591, 596-597 [174 Cal.Rptr. 867, 629 P.2d 961].)12
3. Probable cause to search multiple dwellings.
The warrant affidavit executed by Agent Brown described appellant’s property as including a “structure” with a “light colored roof” and another nearby “structure . . ., possibly a mobil [ízc] trailer.” It indicated that paths ran from each structure to the gardens, leading Brown to believe that the “occupant(s)” controlled the cultivated areas. The affidavit sought permission to search both structures because, in Brown’s experience, commercial marijuana growers typically use “their houses and other outbuildings” to dry, cure, store, and hide their crops. The warrant issued on that basis.
When the warrant was executed, both structures turned out to be trailers used as residences. Both were searched; in the larger, used by appellant and his wife, marijuana and documents were found. Appellant argues that the warrant was fatally defective because the affidavit failed to establish independent probable cause for the search of multiple dwellings.
We cannot agree. In the first place, contrary to appellant’s assertion, there is no indication that Agent Brown negligently or intentionally omitted the [1321]fact of multiple dwellings from the warrant affidavit. (See People v. Kurland (1980) 28 Cal.3d 376, 387-388 [168 Cal.Rptr. 667, 618 P.2d 213], cert. den., 451 U.S. 987 [68 L.Ed.2d 844, 101 S.Ct. 2321].) Detective Vulich testified that both structures looked like dwellings to him from the air, but there is no evidence that this opinion was shared with, or by, Agent Brown. (Cf., United States v. Rios (10th Cir. 1979) 611 F.2d 1335, 1347.)
Moreover, any omission in that regard neither undermined probable cause nor made the warrant affidavit “materially misleading.” (Kurland, supra, 28 Cal. 3d at p. 385.) There was ample information from which the magistrate could reasonably conclude that both structures were connected to the cultivation activities on the parcel, and that both were likely to contain criminal evidence. (Compare People v. Joubert, supra, 118 Cal.App.3d 637, 649-650 [affidavit described “dwelling places and/or outbuildings” on a 28-acre parcel but stated affiant’s opinion only that “the dwelling house” contained criminal evidence]; People v. Sheehan (1972) 28 Cal.App.3d 21, 24-26 [103 Cal.Rptr. 201] [warrant to search “all structures, tents, lean-tos, and campsites” on 315-acre communal ranch, based on discovery of marijuana patch not near any dwelling].)
The judgment is affirmed.
Mosk, J., and Reynoso, J., concurred.
Broussard, J., concurred in the judgment.
The United States Supreme Court has since reached a contrary conclusion on the backyard aerial surveillance issue under the Fourth Amendment. (California v. Ciraolo (1986) — U.S. — [90 L.Ed.2d 210, 106 S.Ct. 1809].) The high court’s ruling is discussed in greater detail below.
The Attorney General explains that this massive law enforcement effort stems from the magnitude of the cultivation problem, related incidents of violence, and the consequent dangers to normal recreational use of California’s back country. As he notes, the 1983 final report of the joint state-federal Campaign Against Marijuana Planting (CAMP) estimates that 80 percent or more of rural marijuana growers in 14 participating counties guard their [1309]plots with firearms during the cultivation and harvest seasons to prevent “poaching.” A number of deaths and serious injuries have resulted. (See, e.g., People v. Dillon (1983) 34 Cal.3d 441 [194 Cal.Rptr. 390, 668 P.2d 697].) Some have involved innocent and accidental intruders. Moreover, precisely because the growers seek to operate in secret, they have retreated into remote areas, including public lands, traditionally frequented by hikers, campers, fishermen, and hunters. The transformation of rural tracts formerly open to recreational use into illegal armed camps posing a danger to innocent wanderers is a major social and environmental problem which itself implicates precious personal freedoms.
Justice Powell’s majority opinion was joined by the Chief Justice and by Justices Black-mun, Rehnquist, and O’Connor. The sixth member of the majority, Justice White, concurred only in the “persons, houses, papers, and effects” analysis. He declined to reach the issue whether one could have a reasonable expectation of privacy in an open field. (Id., at p. 184 [80 L.Ed.2d at p. 228].)
Oliver did not present the issue whether the police may survey open fields at will from the air. However, the majority found little merit in the landowners’ complaints about ground inspection of their open fields, since they conceded “that the public and police lawfully may survey lands from the air.” (P. 179, fn. omitted [80 L.Ed.2d p. 224]; see discussion post.)
For federal purposes, our conclusion seems virtually compelled by Oliver's remark that appellants there had “concedefd]” the right of the police to “survey lands from the air” (466 U.S. at p. 179 [80 L.Ed.2d at p. 224]; see fn. 4, ante), and by the recent holding in Ciraolo that the right of aerial surveillance extends even to the curtilage. However, we do not necessarily accept, for purposes of the California Constitution, Oliver’s ruling that law enforcement agents may constitutionally conduct warrantless ground searches of open fields even where they physically trespass upon private land. Aerial surveillance of crops in fields, from the visual distances we suggest, is not a trespass, and it is substantially less likely than a ground search to infringe on legitimate private activities taking place within open fields.
While we are concerned with the use of optical enhancers, it does not appear feasible to impose a blanket rule prohibiting their employment from aircraft. We establish the principle that the aircraft must maintain a visual distance sufficient to obscure the details of human activity below. Optical enhancers may not be used to shorten that visual distance. (Cf., People v. Arno (1979) 90 Cal.App.3d 505, 510-512 [153 Cal.Rptr. 624].) On the other hand, the safest, most practical, and least intrusive method of surveillance may sometimes be to fly well above the minimum permissible altitude for naked-eye observations, then to utilize magnifying devices to compensate for the increased distance. Here, we are persuaded that use of the telephoto lens did not unreasonably infringe on legitimate privacy on defendant’s property.
Nor do we accept defendant’s suggestion that use of a camera is impermissible, since it allows scrutiny of the photographed area “at leisure.” For federal purposes, the United States Supreme Court has recently concluded that an optical device which “enhanced somewhat” the details visible to the naked eye from a passing aircraft did not raise constitutional concerns. (Dow Chemical, supra, — U.S. at p. — [90 L.Ed.2d at p. 238].) The photos here, taken with a garden-variety 35 millimeter camera, show no potential for useful enhancement or magnification.
But cf., Ciraolo, supra, dissenting opinion of Powell, J., — U.S. at page — [90 L.Ed.2d at page 224] (citing necessarily “indiscriminate” nature of aerial surveillance and photography as “serious threat” to “privacy interests in the home”).
Appellant suggests another means by which the competing law enforcement and privacy interests might be balanced. He proposes that random aerial surveillance which includes homes and curtilages is a “search” but might be justified by an “area” surveillance warrant obtained under somewhat relaxed standards of probable cause. (Cf., e.g., Camara v. Municipal Court (1967) 387 U.S. 523, 535-539 [18 L.Ed.2d 930, 939-941, 87 S.Ct. 1727].) Under this approach, the authorities would have to persuade a neutral magistrate in advance that particular overflights were constitutionally justified. Officers would not, however, be required to demonstrate probable cause to believe that marijuana was growing on every parcel, or any particular parcel, within the anticipated surveillance zone.
The suggestion is appealing at first glance. The warrant clause is the Constitution’s most important safeguard against overzealous government intrusions on legitimate privacy. Nonetheless, a majority of this court have concluded that the proposal must be rejected. It would impose upon law enforcement agencies a cumbersome two-step procedure, with one warrant necessary to permit the initial aerial surveillance, then, in most cases, another to authorize any subsequent ground search. Moreover, we find it difficult to conceive what advance information the officers could provide that would assist the magistrate, except in the most extreme cases, to evaluate the probable merit of a particular proposed overflight. Nor is a magistrate in a position to prejudge the infinite variations in altitude, distance, flight pattern, and air speed which might arise from conditions faced by the aircraft’s pilot.
Proposition 8, adopted by the voters on June 8, 1982, added section 28, subdivision (d) (hereafter section 28(d)) to article I of the California Constitution. Section 28(d) provides, with certain exceptions, that “relevant evidence” shall not be excluded from a criminal proceeding. One effect of section 28(d) is to prohibit application of the “exclusionary rule” to evidence gathered in violation of the state Constitution’s search and seizure clause (art. I, § 13) unless exclusion is compelled by federal constitutional law. (In re Lance W. (1985) 37 Cal.3d 873, 888-890 [210 Cal.Rptr. 631, 694 P.2d 744].) Proposition 8 applies only to crimes committed after its passage. (People v. Smith (1983) 34 Cal.3d 251, 258 [193 Cal.Rptr. 692, 667 P.2d 149].)
Two suppression hearings were held, one at the preliminary hearing and one in the superior court. (See Pen. Code, § 1538.5, subds. (b), (i).) By stipulation, the preliminary hearing transcript was admitted in the superior court hearing.
Agent Brown testified that he had always been vindicated by any ground examination of his past aerial observations; everything observed as marijuana from the air turned out to be marijuana when later examined on the ground. Detective Vulich reported a similar success rate in numerous cases.
Appellant notes the comment in People v. Joubert, supra, 118 Cal.App.3d 637, that optically aided identification of crops in open fields is permissible because, as the cases demonstrate, “the plants cannot truly be identified as marijuana at reasonable altitudes without the aid of binoculars; ...” (P. 646.) However, probable cause, not certain identification, is the issue. We are not persuaded that officers observing from “reasonable altitudes” with the naked eye alone lack all basis for forming a strong and reasonable suspicion, even if they cannot see each stalk, leaf, and bud. The plants are sizeable; indeed, the record is rife with indications that, at maturity, they can exceed 20 feet in height.