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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 The beeper gave way to the flip phone, which has largely been replaced by the “smart­phone,” a mini-computer that fits in the palm of your hand and is more power­ful than the desktop machine of the 1980s.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