Observations from above: unmanned aircraft systems and privacy.

• Author: Villasenor, John
• Position: III. Government Unmanned Aircraft and the Fourth Amendment through Conclusion, with footnotes, p. 475-517 - Privacy, Security, and Human Dignity in the Digital Age

3. GOVERNMENT UNMANNED AIRCRAFT AND THE FOURTH AMENDMENT

   The Fourth Amendment is central to the privacy issues with respect to government UAS operation. Although the Supreme Court has never explicitly considered the question of UAS privacy, there is a long list of relevant precedents. (90) Among them are several cases from the 1980s that specifically considered aerial observations and the Fourth Amendment. The 2001 Kyllo v. United States (91) and 2012 United States v. Jones (92) decisions are also pertinent.

   1. Dow Chemical Co. v. United States

      In 1978, the Environmental Protection Agency, without Dow Chemical's consent, contracted with a commercial aerial photographer to provide images of a 2000-acre Dow Chemical manufacturing facility from altitudes of 1200, 3000, and 12,000 feet. (93) When Dow Chemical became aware of this, it filed suit in Federal District Court, which granted summary judgment, finding the aerial photography to be a search in violation of the Fourth Amendment. (94) The Sixth Circuit reversed the decision, ruling that even though the company had taken precautions, including installing a perimeter fence and alarm system (95) that provided a subjective expectation of privacy from ground-level intrusions, it did not have such an expectation with respect to aerial surveillance. (96) Thus, the Sixth Circuit concluded, the acquisition of aerial images without a warrant was not a Fourth Amendment search. (97)

      In reviewing this ruling on certiorari, the Supreme Court affirmed the Sixth Circuit's decision, concluding in a 1986 ruling that the open areas in the 2000-acre industrial facility were more akin to an "open field" (98) than to the curtilage of a home, and, as a result, were "open to the view and observation of persons in aircraft lawfully in the public airspace immediately above or sufficiently near the area for the reach of cameras." (99) The Court also noted the role of technology diffusion as a factor, writing that "surveillance of private property by using highly sophisticated surveillance equipment not generally available to the public, such as satellite technology, might be constitutionally proscribed absent a warrant." (100) However, the Court observed, "[a]ny person with an airplane and an aerial camera could readily duplicate" (101) the photographs at issue. "[T]he taking of aerial photographs of an industrial plant complex from navigable airspace is not a search prohibited by the Fourth Amendment." (102)

   2. California v. Ciraolo

      Ciraolo (103) was decided in 1986, on the same day as Dow Chemical. On September 2, 1982, police in Santa Clara, California, received a tip regarding backyard marijuana cultivation. (104) After finding the yard surrounded by high fencing obscuring the view from the street, they obtained a small airplane and flew over the residence at 1000 feet. (105) The officers on the airplane observed and photographed what they concluded to be marijuana plants growing in the backyard. (106) This evidence was used to obtain a search warrant to seize the plants. (107)

      The Supreme Court granted certiorari after the California Court of Appeal ruled that the warrantless aerial observations violated the Fourth Amendment. (108) In May 1986, the Supreme Court issued a five-to-four decision reversing the lower court. (109) Writing for the majority, Chief Justice Burger framed the analysis in terms of the "reasonable expectation of privacy" (110) articulated in Justice Harlan's concurrence in Katz. (111) For an expectation of privacy to be "reasonable" under Katz, two separate criteria must be satisfied. First, the person must "have exhibited an actual (subjective) expectation of privacy." (112) Second, the expectation must "be one that society is prepared to recognize as 'reasonable."' (113)

      With respect to the first criterion, the Ciraolo Court wrote that although the presence of fences clearly conveyed a "desire to maintain privacy," and indeed successfully did so with respect to "normal sidewalk traffic," the marijuana plants might well have been visible from a truck or two-level bus. (114) Thus, it was unclear that the respondent had "a subjective expectation of privacy from all observations of his backyard." (115)

      With respect to the second criterion, the Court did not dispute that the backyard was in the curtilage of the home, (116) but noted that police observations of curtilage are not necessarily unconstitutional. "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." (117) Moreover, "the mere fact that an individual has taken measures to restrict some views of his activities [does not] preclude an officer's observations from a public vantage point where he has a right to be and which renders the activities clearly visible." (118) Because the observations were made from "public navigable airspace ... in a physically nonintrusive manner," the respondent's expectation of privacy from such aerial observations was not one "that society is prepared to honor." (119) The Court concluded that "[i]n 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." (120)

      The dissent, delivered by Justice Powell, criticized the Court's reliance on the absence of a "physical invasion of the curtilage" in finding no constitutional violation: "Since Katz, we have consistently held that the presence or absence of physical trespass by police is constitutionally irrelevant to the question whether society is prepared to recognize an asserted privacy interest as reasonable." (121) The dissent also disagreed with the Court's view that conducting an overflight with the specific goal of enabling trained officers to observe a suspect's backyard raised no more constitutional questions than overflights by members of the flying public: "IT]he actual risk to privacy from commercial or pleasure aircraft is virtually nonexistent. Travelers on commercial flights, as well as private planes used for business or personal reasons, normally obtain at most a fleeting, anonymous, and nondiscriminating glimpse of the landscape and buildings over which they pass." (122) And, in an observation that would foreshadow the Kyllo decision fifteen years later, Justice Powell warned that "[r]apidly advancing technology now permits police to conduct surveillance in the home itself, an area where privacy interests are most cherished in our society, without any physical trespass." (123)

   3. Florida v. Riley

      Just under three years after Ciraolo, the Supreme Court once again ruled on the constitutionality of aerial observations of a home's curtilage by law enforcement. Like Ciraolo, Florida v. Riley (124) arose from a tip involving marijuana cultivation behind a house, where the plants could not be seen from the street. In Riley, the observations were made from a helicopter at 400 feet, enabling officers to see the plants through openings in the roof and sides of a greenhouse located behind a mobile home. (125) A majority of the justices in Riley found these observations constitutional.

      Writing for the plurality, (126) Justice White wrote that "our decision in California v. Ciraolo controls this case." (127) While Riley took steps that "protected against ground-level observation," "the sides and roof of his greenhouse were left partially open" and "what was growing in the greenhouse was subject to viewing from the air." (128) "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." (129)

      Despite Justice White's statement that "[w]e would have a different case if flying at that altitude had been contrary to law or regulation," (130) his opinion also provided an important qualifier: "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." (131) Specifically, in ruling that there was no violation of the Fourth Amendment in the present case, Justice White found it of note that "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." (132)

      In her opinion concurring in the judgment, Justice O'Connor raised concerns about relying on "compliance with FAA regulations alone" as a litmus test for privacy from overhead surveillance. (133) Rather, she wrote, "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."' (134) She then concluded that because there is "considerable public use of airspace at altitudes of 400 feet and above," Riley did not have a reasonable expectation of privacy from naked-eye observations from that altitude. (135) However, she wrote, "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." (136)

      Justice Brennan's dissent also took issue with the tie between FAA safety regulations and privacy: "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," (137) He observed that the police officer's "ability to see over Riley's fence depended on...