Does the Fourth Amendment, which protects against “unreasonable searches and seizures,” prohibit warrantless drone surveillance? The Supreme Court has yet to answer that question, but an appeals court in Michigan recently considered the question, and in an opinion written by Judge Kathleen Jansen answered “Yes.” The court’s analysis is particularly noteworthy in that it relied heavily on Fourth Amendment cases besides those dealing specifically with aerial surveillance and may encourage other judges to do likewise when considering the constitutionality of warrantless drone surveillance.

The facts of the case, Long Lake Township v. Todd Maxon, are as follows: officials in Long Lake Township, Michigan alleged that a couple, Todd and Heather Maxon, had violated local zoning ordinances by keeping an excessive number of junk cars and other materials on their property. To support its case against the Maxons, Long Lake Township attached photographs of the Maxon property taken via drone. The Maxons moved to suppress these photos, arguing that Long Lake Township’s warrantless photography of their property from the air constituted a violation of the Fourth Amendment.

Since 1967, the touchstone of Fourth Amendment has been the so‐​called Katz test, codified by Justice Harlan in his solo Katz v. United States concurrence. Under the test, a government official is deemed to have conducted a Fourth Amendment search if two conditions are met: 1) the subject of surveillance has exhibited a subjective expectation of privacy, and 2) that subjective expectation is one society as a whole is prepared to accept as reasonable.

The Supreme Court has considered the constitutionality of aerial surveillance in three cases from the 1980s (California v. Ciraolo, Florida v. Riley, Dow Chemical v. United States) and held in all three that that manned warrantless aerial surveillance does not violate the Fourth Amendment.

As Chief Justice Burger wrote in the majority opinion in California v. Ciraolo, a case involving police using an airplane to snoop on a backyard:

The observations by Officers Shutz and Rodriguez 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. That the observation from aircraft was directed at identifying the plants and the officers were trained to recognize marijuana is irrelevant. Such observation is precisely what a judicial officer needs to provide a basis for a warrant. 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 respondent’s expectation that his garden was protected from such observation is unreasonable, and is not an expectation that society is prepared to honor.

The Supreme Court has yet to modify or overrule this precedent in response to the rapidly evolving technology of aerial surveillance. When confronted with the issue in Long Lake, Judge Jansen relied on another set of cases that didn’t involve aerial surveillance at all: Kyllo v. United States (2001), which considered the warrantless use of a thermal scanner, and Carpenter v. United States (2018), a case concerning the warrantless collection of cell site locator information (CSLI).

In Kyllo, the Supreme Court ruled that the warrantless use of a thermal imaging device on a suspected marijuana grower’s home violated the Fourth Amendment. Writing for the majority in his Kyllo, Justice Scalia explained that:

Where, as here, the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a ‘search’ and is presumptively unreasonable without a warrant.

The Supreme Court ruled in Carpenter that the government cannot access days worth of CSLI without a warrant. Although the facts of Carpenter appear at first blush to have little in common with the aerial drone surveillance at issue in Long Lake, Judge Jansen noted Chief Justice Roberts’ reasoning in Carpenter that someone can retain a reasonable expectation of privacy in public even if the government develops cheaper ways to conduct mass surveillance. Thus, the mere fact that cell site location information is often used for commercial purposes does not mean that cell‐​phone users have surrendered to the government an expectation of privacy regarding their physical location.

Marshalling the reasoning in Kyllo and Carpenter, Judge Jansen concludes that new technologies do not in and of themselves negate a reasonable expectation of privacy in what can be observed from a public space.

The Long Lake majority distinguishes the Supreme Court’s aerial‐​surveillance precedent by noting that drone surveillance is qualitatively different from surveillance conducted by airplane (Ciraolo) or helicopter (Riley), just as the thermal scanner in Kyllo was qualitatively different from earlier, less capable surveillance devices.

While placing substantial emphasis on the particular nature of technology used to conduct the surveillance, Judge Jansen gave little weight to the fact that the drone operator photographing the Maxon property did so within Federal Aviation Administration (FAA) guidelines. Indeed, as Judge Jansen sees it, the fact that the FAA has specific drone rules argues in favor of their qualitative differences from airplanes and helicopters. She goes on to point out that even if the drone flights in this case were a trespass the Fourth Amendment does not prohibit all government trespass into “open fields.”

Rejecting an altitude test, the she concludes: “[P]ersons have a reasonable expectation of privacy in their property against drone surveillance, and therefore a governmental entity seeking to conduct drone surveillance must obtain a warrant or satisfy a traditional exception to the warrant requirement.”

This analysis has many attractive features for civil libertarians. For one, it curbs intrusive warrantless surveillance via a relatively new technology without having to overturn long‐​standing Supreme Court precedent and seeks to ensure that the Fourth Amendment is not left in tatters by advances in technology. Yet the opinion is not without its issues. Its analysis of Kyllo is especially dubious, as the dissenting Judge Karen Fort Hood explains in her dissent. As I noted above, Scalia wrote in Kyllo (emphasis mine): “uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a ‘search’ and is presumptively unreasonable without a warrant.”

But the drone at issue in Long Lake Township is hardly a rare piece of surveillance equipment “not in general public use.” To the contrary, drones are increasingly common and being used by a range of professionals and hobbyists. As Judge Hood noted in her dissent:

Defendants have not provided any evidence that the type of drone used in this case was a technology unavailable to the general public. Contrarily, drones are generally widely available to the public, there is reason to believe that the public commonly flies them at altitudes of 400 feet and below, and there is no evidence in this case that the drone in question was flying at a particularly invasive altitude or in a particularly invasive manner, or that the drone contained or used any particularly invasive technology. Similar to Ciraolo and Riley, there is reason to believe that any member of the public could have used their own drone and plainly viewed the property at issue in this case.

Kyllo may well be a case civil libertarians should keep in mind for controversies involving new and emerging surveillance technologies, but when it comes to drone surveillance its reliance on “general public use” seems to render it unworkable.

That should not leave civil libertarians complacent. Almost twenty state legislatures have already passed drone warrant requirements, another reminder that the Supreme Court sets the floor, not the ceiling. Supreme Court precedent may not require warrants for drone surveillance, but state lawmakers can improve upon that standard.

Whether the analysis in Judge Janesen’s majority opinion will prove influential with other courts remains to be seen. Thanks to drones being increasingly in “general public use,” more courts across the country will no doubt be tackling cases similar to Long Lake Township v. Maxon. It will be interesting to see how many of these courts adopt a similar Kyllo sidestep around the Supreme Court’s less privacy‐​friendly aerial‐​surveillance case law.