Can the Fourth Amendment Survive Digital Surveillance?

Advances in technology used by law enforcement to gather information about people without a warrant has eroded Americans’ right to privacy.

(Composite /Photos: GettyImages / Shutterstock)

The Fourth Amendment guarantees “the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” The Founders opposed the British practice of issuing “general warrants”—edicts that allowed government officers to undertake sweeping searches without suspicion. As Justice Robert Jackson put it: “The forefathers, after consulting the lessons of history, designed our Constitution to place obstacles in the way of a too permeating police surveillance.”

The advance of technology has long bedeviled Fourth Amendment jurisprudence. A century ago, in Olmstead v. United States (1928), a case involving the warrantless wiretapping of telephones, Louis Brandeis urged his fellow justices not to let the amendment wither as “subtler and more far-reaching means of invading privacy” become “available to the government.” They did not listen. The Supreme Court permitted the wiretaps, reasoning that the Fourth Amendment cares only about searches of “material things.” Brandeis saw that the “progress of science” would continue, making that position increasingly untenable. At length it became too embarrassing to maintain. The Court overturned Olmstead in 1967.

Increasingly effective tools of surveillance could grind the Fourth Amendment into dust. The issue is more pressing than ever. Consider the outside of your home. Because it is open to public view, the Fourth Amendment, as traditionally understood, affords it no protection. The authorities may keep an eye on it for (almost) any reason or for no reason. In the past, though, the state would have needed a good reason, since keeping up a watch would have required assigning policemen to conduct a stakeout. Now all it has to do is hide a small video camera across the street.

That’s what happened to Daphne Moore. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) suspected Moore’s daughter of selling guns and drugs out of Moore’s home in Springfield, Massachusetts. So ATF agents (no warrant in hand) placed a digital camera high on a utility pole, trained it down on the house, and proceeded to track the goings-on there, via a 24/7 livestream, for the next eight months.

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After being indicted on drug charges, Moore and her daughter moved to suppress evidence obtained from the pole camera. Though the effort failed, three judges on the U.S. Court of Appeals for the First Circuit accepted the argument that the surveillance amounted to an unreasonable search under the Fourth Amendment. The ACLU has petitioned the Supreme Court for review, and the Court has directed the government to submit a response (a sign that the justices are interested in hearing the case).

Over the last quarter century, the Court has taken some half-hearted stabs at applying the Fourth Amendment to new technology. If the police use an infrared thermal imaging device to measure the heat coming off your house, that (absent a warrant) is an unreasonable search (Kyllo v. United States [2001]). Ditto if they attach a GPS device to your car (United States v. Jones [2012]). The police generally can’t ransack your smartphone without a warrant when you’re arrested (Riley v. California [2014]), and they likewise need a warrant to obtain records of your smartphone’s location (Carpenter v. United States [2018]).

These rulings are limited in scope. In Kyllo, it mattered to the Court that the heat detector was “not in general public use.” It mattered in Jones that the state attached the GPS device to—and thus “physically occupied” a piece of—the vehicle. Riley protects your smartphone data only from a search incident to arrest. And Carpenter is a “narrow” decision that does not “call into question conventional surveillance techniques and tools, such as security cameras.”

Why has the Court been so hesitant? One reason is that, while many of the justices subscribe to originalism, the Fourth Amendment does not lend itself to a straightforward originalist reading. The Founders worried about the government breaking down their doors and rifling through their desks. Today people worry about it mapping their public movement and their online habits. Trying to analogize from the text of the Fourth Amendment, with its focus on one’s material possessions, to modern concerns about digitized surveillance is an intellectually fraught task.

In Jones, for example, the justices agreed that the use of the GPS device was an unreasonable search; but they disagreed about why that was so. The majority stressed that the government had “trespassorily inserted” the device onto the suspect’s Jeep, in contravention of ancient principles of tort law. In a concurrence, Justice Samuel Alito (no progressive) maligned this approach, calling it “highly artificial.” “It is almost impossible,” he complained, “to think of late 18th-century situations that are analogous to what took place in this case.” Writing for the majority, Justice Antonin Scalia responded that placing a GPS device on a car perhaps resembles “a constable’s concealing himself in the target’s coach.” To which Alito retorted: “this would have required either a gigantic coach, a very tiny constable, or both.”

If the authorities may continuously monitor the front of any home without a warrant, nothing, in principle, stops them from continuously monitoring the front of every home without a warrant. And if they may monitor the neighborhood in this way, all the more so may they monitor the parks, streets, squares, and other public spaces. What’s more, the monitoring devices now available to them can identify individuals, read license plates, pick out small items (such as keys), capture facial expressions, and spot various patterns of behavior.

Many cities in China collect unfathomable quantities of such information, feeding it into networked platforms. Even local precincts use those products, often in command centers of the sort once possessed only by organizations like the CIA. Little human supervision is needed; everything is analyzed by artificial intelligence, which flags people of interest (including political dissidents) and undesirable activity (including any whiff of protest). The capacity to store intelligence for later use is now practically infinite. And of course, modern governments in China and elsewhere are not limited to watching the outside world. With publicly available data, as well as input from obliging tech companies, state agencies the world over can use the Internet to trace out a person’s politics, relationships, health, and lifestyle.

Does the Fourth Amendment block any of this? The Supreme Court has granted the state broad authority to monitor “public thoroughfares,” including with “such enhancement” of police officers’ senses “as science and technology afford[] them.” It has placed only very weak checks on the state’s ability to gather information about a person from third parties. And it has put no limits on how the state pools and analyzes information it has lawfully collected. The conservative justices, in particular, remain focused on protecting against the physical invasion of people, their homes, and their belongings (a worthy goal, to be sure) rather than on restraining the government’s power, through data acquisition and manipulation, to make each citizen hyper-legible (potentially an even greater danger, in the long run).

Without needing to search your physical stuff—your person, house, papers, or effects—our government could, in theory, still construct a surveillance state, a digital panopticon akin to what China has imposed on its Uyghur minority. Even a regime that fell far short of achieving such full-blown dystopia could institute a far too permeating surveillance. And yet it is not at all clear whether Fourth Amendment doctrine, as we know it, could respond to the threat. It is a jurisprudence that remains largely blind to what pervasive, cutting-edge sensors, big data, and advanced computing can achieve in the aggregate.

Fortunately, the outcome in Daphne Moore’s case, at least, should be obvious. “The house of every one,” Lord Coke proclaimed in 1604, “is to him as his castle and fortress.” It was in service of this ideal that the Founders sought to preserve the “right of the people to be secure” in their “houses.” Following Brandeis’s lead, the Supreme Court’s liberal justices will not shrink from updating the Constitution, as needed, to keep pace with the progress of science and limit police intrusions on the home. And in this instance, if nowhere else, the conservatives have solid grounds for following a similar path.

Think back to Kyllo, a decision written by that quintessential originalist, Justice Scalia. As technology improves, Scalia contended, the Court must protect “that degree of privacy against government that existed when the Fourth Amendment was adopted.” And “to withdraw protection” from the interior of the home, he reasoned, “would be to permit police technology” to “erode” that “guaranteed” constitutional floor. A “mechanical” reading of the Fourth Amendment, he concluded, “would leave the homeowner at the mercy of advancing technology—including imaging technology that could discern all human activity in the home.” Heat-detection technology might, in time, become similarly invasive. The device at issue in Kyllo was “relatively crude,” but the Court had, Scalia believed, to “take account of more sophisticated systems that are already in use or in development.” So although it technically “captures only heat emanating from a house,” a thermal imager may not, Scalia ruled, be used without a warrant.

This logic easily extends to video monitoring of a house’s front yard. Like heat detection, such surveillance, though technically external, draws out many facts about what occurs inside the home—who is present (and how often), what gets delivered (or discarded), what occurs in view of the windows (or inside an open garage), and more.

As Justice Scalia observed, a judge must construe a text not strictly, and not leniently, but “reasonably, to contain all that it fairly means.” In the years to come, the justices will have to decide whether the text of the Fourth Amendment, reasonably construed, blocks the government from creating general warrants in digital form.