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Expert Brief

Hiding in Plain Sight

Over the last several decades, the range and capabilities of easily available technologies that enable a granular view of citizens’ movements and associations in public, over long periods of time and at a relatively cheap cost, have expanded at an astonishing pace. Where law enforcement is involved, these powerful new technologies raise questions about how their use can be harmonized with the U.S. Constitution.

Published: March 21, 2017

This first appeared as a law review article, “Hiding in Plain Sight: A Fourth Amendment Framework for Analyzing Government Surveillance in Public,” published in the Emory Law Journal in March 2017.

As the sophistication and availability of digital technologies that enable government surveillance reach unprecedented levels, Courts are increasingly finding that the Fourth Amendment must be adapted to protect Americans from new forms of “unreasonable searches and seizures.”

In this article for the Emory Law Review, Rachel Levinson-Waldman reviews the courts’ evolution on the Fourth Amendment implications of surveillance in the public space, outlines a new approach for courts and law enforcement to use in assessing Fourth Amendment implications of surveillance, and examines several cases studies to explore the practical implications of this approach.

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Over the last several decades, the range and capabilities of easily available technologies have expanded at an astonishing pace. The beeper gave way to the flip phone, which has largely been replaced by the “smartphone,” a mini-computer that fits in the palm of your hand and is more powerful than the desktop machine of the 1980s. Paper maps are increasingly rare, replaced by built-in Global Positioning System (GPS) devices or the ubiquitous smartphone. The days of having to keep change in a glove compartment to pay a toll attendant are long past; instead, an EZ-Pass reader enables drivers to travel seamlessly across multiple states and pay the charges directly from an online account.

These and other technologies, which are valuable to civilians and law enforcement alike, also enable a granular view of citizens’ movements and associations in public over long periods of time at a relatively cheap cost. The 2002 movie Minority Report, which seemed wildly futuristic at the time, effectively predicted many of the technologies now available to police at the click of a button: drones, facial recognition scanners, vehicle trackers, and more.

Where law enforcement is involved, these powerful new technologies also raise questions about how their use can be harmonized with the U.S. Constitution. The Fourth Amendment guarantees “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” Under what circumstances does an eye in the sky (or on a pole, or inside your phone) constitute a search under the Fourth Amendment—and thus presumptively require a warrant—when it is used for public surveillance?

It seems inconceivable that the Founders, who could fairly be described as obsessed with Americans’ right to be let alone, could have envisioned, let alone endorsed, the degree and depth of intrusion into individuals’ lives that is enabled by present-day surveillance technologies.  At the same time, it is notoriously difficult to articulate when surveillance in public works a constitutional violation and when it is simply the price for leaving the house. While the judiciary is nowhere near consensus, courts are finding that some public manifestations of this new, digitally-enabled tracking are so inimical to any standard notions of privacy that the Fourth Amendment imposes limits on their use, as discussed in further detail below.

The home has always been sacrosanct territory for the Fourth Amendment. In the late 1960s, the Supreme Court began to expand its conceptions of the Fourth Amendment’s protections beyond the doorstep. In United States v. Katz, involving a payphone (then a cutting-edge technology), the Court laid the groundwork for a doctrine holding that the Fourth Amendment protects individuals from police intrusion when the intrusion violates a “reasonable expectation of privacy.”  A couple of decades later, the Supreme Court confronted another novel technology, which police were using to tail criminal suspects: the beeper.

In two key Supreme Court cases, police officers planted beeper devices in suspects’ cars and used their signals to follow the car when a close physical tail was impractical or would have revealed the surveillance. In these cases, the Court concluded that because the police could have freely followed and observed the suspects on public roads and highways without getting a warrant, using a beeper to make the job a little easier did not sound constitutional alarms. Although the Court warned that its analysis might not hold if the police undertook dragnet surveillance, its reasoning has long been used as support for the broad proposition that there is no reasonable expectation of privacy in one’s movements in public space. 

Of course, the stock-in-trade of good policing often involves the real-time observation of people going about their daily business. This kind of visual observation, while potentially intrusive or discomfiting to the subject or passersby, does not raise constitutional issues. It is also, however, cost- and resource-intensive. These costs have historically required law enforcement agencies to make critical judgments about what types of police work and surveillance to undertake, and they have acted as an effective brake on at least some kinds of government overreach. Practical limitations on government surveillance in public offered “structural privacy,” privacy arising not from legislative or judicial decisionmaking, but from the physical and technical limitations on carrying out long-term, wide-range surveillance of multiple persons or areas.

Enter digital technology. As surveillance techniques grow ever more technologically sophisticated, the quantum of data that is easily available grows as well, while the cost of obtaining, keeping, and analyzing it generally drops. At the same time, “our historical expectations of privacy do not change or somehow weaken simply because we now happen to use modern technology to engage in activities in which we have historically maintained protected privacy interests.” How, then, is the judiciary “to adapt traditional Fourth Amendment concepts to the Government’s modern, more sophisticated investigative tools”?

This Article proposes one way to meet this challenge. Existing case law, seen through a new lens, provides the blueprint for a workable, comprehensive mechanism for applying the Fourth Amendment to digital age public surveillance technologies. This approach aggregates factors courts have already identified as relevant to their Fourth Amendment analysis, but in an ad hoc manner, and transforms them into a more rigorous, replicable approach.

These factors are: (1) the duration of the surveillance; (2) the lowering of structural barriers to pervasive surveillance, reflected in the greatly reduced cost of tracking; (3) the recording of an individual’s or group’s movements; (4) the elicitation of information from within a protected space such as a home; and, as appropriate, (5) whether the technology undermines core constitutional rights and (6) whether surveillance technologies are piggy-backed on each other. Pulling out and articulating these factors, and analyzing how and why they should be considered, seeks to add rigor to the improvisatory method that has defined the judiciary’s consideration of these questions.

Once the Fourth Amendment is triggered, the Constitution generally requires police to get a warrant, which must meet the particularity standard. That will usually be possible through careful ex ante and ex post tailoring; where it is not, that use of the surveillance technology may not be compatible with the Constitution. In addition, courts must be alert to attempts to justify a wide swath of surveillance activities on the grounds that they satisfy a “special need,” an exception to the warrant requirement that could quickly swallow the rule.

* * *

This Article proceeds as follows: Part I provides a brief overview of the courts’ evolution on the Fourth Amendment implications of surveillance in the public space, from initial hints that dragnet surveillance might be problematic to growing recognition that modern methods of information capture and public space surveillance pose privacy concerns of constitutional magnitude. Part II outlines a new, multi-factor approach for both courts and law enforcement to use in assessing whether the Fourth Amendment is implicated by surveillance in public, drawing on existing case law and various scholarly approaches. It assesses how a warrant for surveillance in public can meet the Fourth Amendment’s particularity standard and explores why the special needs exception to the warrant requirement will rarely come into play. It also briefly addresses the circumstances in which the First Amendment and Fourteenth Amendment may provide avenues for relief. Finally, Part III uses several case studies to explore how this approach plays out in the context of specific technologies that facilitate surveillance in public.


Hiding in Plain Sight: A Fourth Amendment Framework for Analyzing Government Surveillance in Public by The Brennan Center for Justice on Scribd