476 U.S. 207 (1986)
On September 2, 1982, Santa Clara Police received an anonymous telephone tip that marijuana was growing in respondent's backyard.1 Police were unable to observe the contents of respondent's yard from ground level because of a 6-foot outer fence and a 10-foot inner fence completely enclosing the yard.2
Later that day, Officer Shutz, who was assigned to investigate, secured a private plane and flew over respondent's house at an altitude of 1,000 feet, within navigable airspace; he was accompanied by Officer Rodriguez.3 Both officers were trained in marijuana identification.4 From the overflight, the officers readily identified marijuana plants 8 feet to 10 feet in height growing in a 15- by 25-foot plot in respondent's yard; they photographed the area with a standard 35mm camera.5
On September 8, 1982, Officer Shutz obtained a search warrant on the basis of an affidavit describing the anonymous tip and their observations; a photograph depicting respondent's house, the backyard, and neighboring homes was attached to the affidavit as an exhibit.6 The warrant was executed the next day and 73 plants were seized; it is not disputed that these were marijuana.7
After the trial court denied respondent's motion to suppress the evidence of the search, respondent pleaded guilty to a charge of cultivation of marijuana.8 The California Court of Appeal reversed, however, on the ground that the warrantless aerial observation of respondent's yard which led to the issuance of the warrant violated the Fourth Amendment.9 The California Supreme Court denied the State's petition for review.10 The Supreme Court granted the State's petition for certiorari.11
Whether the Fourth Amendment is violated by aerial observation without a warrant from an altitude of 1,000 feet of a fenced-in backyard within the curtilage of a home?12
The touchstone of Fourth Amendment analysis is whether a person has a constitutionally protected reasonable expectation of privacy.13 Katz posits a two-part inquiry: first, has the individual manifested a subjective expectation of privacy in the object of the challenged search? Second, is society willing to recognize that expectation as reasonable.14 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.15 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. This is true where he has a right to be and the activities are clearly visible.16
No. Respondent took steps to shield his yard with fences, manifesting a subjective expectation of privacy from ground level views.17 However, the officers conducted the observation from public navigable airspace at 1,000 feet in a physically nonintrusive manner, observing plants readily discernible to the naked eye as marijuana.18 Any member of the public flying in this airspace who glanced down could have seen everything that these officers observed.19 Therefore, respondent's expectation that his garden was protected from such observation is unreasonable and is not an expectation that society is prepared to honor.20
The aerial observation without a warrant did not violate the Fourth Amendment.21
Related opinions on this issue
Joined by Justice Brennan, Justice Marshall, And Justice Blackmun
Justice Powell, joined by Justices Brennan, Marshall, and Blackmun, dissented.22 He argued that the Court's holding rests on only one obvious fact, namely, that the airspace generally is open to all persons for travel in airplanes, but this single fact does not deprive citizens of their privacy interest in outdoor activities in an enclosed curtilage.23
Powell contended that the actual risk to privacy from commercial or pleasure aircraft is virtually nonexistent, as travelers normally obtain at most a fleeting, anonymous, and nondiscriminating glimpse.24 He emphasized that purposeful police surveillance from the air into the curtilage is qualitatively different from public use of the airspace and requires a warrant under the Fourth Amendment.25