California v. Ciraolo, 476 U.S. 207; 106 S. Ct. 1809; 90 L. Ed. 2d 210 (1986)

Facts—Policemen acted on a tip that Ciraolo was growing marijuana in his backyard. Because of an inner and outer high fence it was difficult to see anything. The police secured a private plane and at an altitude of 1,000 feet flew over the marijuana patch, made naked-eye observations, and on this basis got a search warrant. The defendant pleaded guilty, the California Court of Appeals reversed and on certiorari the Supreme Court heard the case.

Question—Does a warrantless aerial observation of a marijuana patch violate the Fourth Amendment?

Decision—No.

Reasons—C.J. Burger (5–4). The touchstone of the Fourth Amendment analysis is whether a person has a “constitutionally protected reasonable expectation of privacy.” 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.” The police observations “took place within public navigable airspace . . . any member of the public flying in this airspace who glanced down could have seen everything that these officers observed.” J. Harlan noted that one who enters a telephone booth is entitled to assume that his conversation is not being intercepted; but this does not translate into “a rule of constitutional dimensions that one who grows illicit drugs in his backyard is entitled to assume his unlawful conduct will not be observed by a passing aircraft or by a power company repair mechanic on a pole overlooking the yard.” The Fourth Amendment does not require police flying in public space to obtain a warrant in order to observe what is visible to the naked eye. Reversed.

J. Powell authored a dissent arguing that the Court was reverting to its stance, used prior to Katz v. United States (1967), focusing unduly on whether a physical trespass had occurred.