Persistent Aerial Surveillance and the Fourth Amendment

The police can fly a plane over your house and look down to see whether you are growing marijuana in your backyard. California v. Ciraolo, 476 U.S. 207 (1986). But can the police fly a plane over everyone’s house, all the time, and record everything visible from the sky? This isn’t a law school hypothetical.

It’s the question central to the business model of a company called Persistent Surveillance Systems. It provides “wide area surveillance” to police departments. In simple terms, it operates planes that circle high above cities, recording everything with a high resolution camera. And now, according to its website, it has a night vision system, so darkness isn’t a problem. The company has received some attention recently, including two excellent Radiolab podcasts, here and here. It did a months-long pilot in Baltimore and has provided services in other cities as well. At least based on the podcasts, it sounds like the technology works and has been used to solve some serious crimes.

Does this violate the Fourth Amendment’s prohibition against unreasonable searches and seizures? It may not be a search at all under Ciraolo, where the Court wrote:

The observations by [the officers] in this case took place within public navigable airspace . . . in a physically nonintrusive manner; from this point, they were able to observe plants readily discernible to the naked eye as marijuana. . . . Any member of the public flying in this airspace who glanced down could have seen everything that these officers observed. On this record, we readily conclude that [the defendant’s] expectation that his garden was protected from such observation is unreasonable, and is not an expectation that society is prepared to honor.

But it is possible to distinguish Ciraolo and develop arguments that persistent aerial surveillance implicates the Fourth Amendment:

  • Different recording technology. In Ciraolo, the officers took at least one picture, using “a standard 35mm camera.” But Persistent Surveillance Systems uses 100+ megapixel cameras that capture multiple square miles in detail. Maybe that matters. In Dow Chemical Co. v. United States, 476 U.S. 227 (1986), a case involving aerial surveillance of an industrial plant, the Supreme Court suggested that extremely powerful imaging from the air might give rise to Fourth Amendment concerns, stating: “It may well be, as the Government concedes, 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. But the photographs here are not so revealing of intimate details as to raise constitutional concerns. Although they undoubtedly give [the government] more detailed information than naked-eye views, they remain limited to an outline of the facility’s buildings and equipment. The mere fact that human vision is enhanced somewhat, at least to the degree here, does not give rise to constitutional problems.” If the surveillance cameras are effective at night, that might also add weight to the constitutional concern. See Kyllo v. United States, 533 U.S. 27 (2001) (ruling that the use of thermal imaging technology on a house was a Fourth Amendment search). But see United States v. Dellas, 355 F. Supp. 2d 1095 (N.D. Cal. 2005) (noting that “several lower courts have held that Kyllo is inapplicable to searches that employ night vision equipment,” because night vision equipment “merely amplif[ies] ambient light to allow the wearer to see in relative darkness”).
  • Different duration. In United States v. Jones, __ U.S. __, 132 S.Ct. 945 (2012), a case about the use of a GPS device to track a suspect’s car, a majority of Justices of the United States Supreme Court appeared to conclude that protracted, long-term surveillance may compromise a reasonable expectation of privacy even when the same type of surveillance, done briefly, does not. I’ve written before about the evolving case law applying the so-called mosaic theory of the Fourth Amendment to body cameras and stationary cameras. Similarly, a court might find that protracted aerial surveillance is not governed by Ciraolo.


I’m not aware of a single case addressing the constitutionality of persistent aerial surveillance, but I am certain that we will have them soon. Persistent Surveillance Systems uses planes, which are expensive, meaning that only a few cities can afford the technology. But every year, better and better cameras can be mounted on cheaper and cheaper drones, bringing similar capabilities within reach of many more law enforcement agencies.

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