Structural Sensor Surveillance

• Author: Andrew Guthrie Ferguson
• Position: Professor of Law, American University Washington College of Law
• Pages: 47-112

47

Structural Sensor Surveillance

Andrew Guthrie Ferguson*

ABSTRACT: City infrastructure is getting smarter. Embedded smart sensors

in roads, lampposts, and electrical grids offer the government a way to

regulate municipal resources and the police a new power to monitor citizens.

This structural sensor surveillance, however, raises a difficult constitutional

question: Does the creation of continuously-recording, aggregated, long-term

data collection systems violate the Fourth Amendment? After all, recent

Supreme Court cases suggest that technologies that allow police to monitor

location, reveal personal patterns, and track personal details for long periods

of time are Fourth Amendment searches which require a probable cause

warrant.

This Article uses the innovation of smart city structural design as a way to

rethink current Fourth Amendment theory. This Article examines the Fourth

Amendment search questions that may render structural surveillance

unconstitutional, and then offers a legal and practical design solution. The

Article argues that Fourth Amendment principles must be built into the

blueprints of urban design. At a micro-level, privacy rules must be embedded

alongside data collection rules. At a macro-level, a comprehensive legal

framework must be integrated with digital design choices. Only by thinking

about municipal code and computer code simultaneously can smart cities

avoid emerging Fourth Amendment challenges.

I.INTRODUCTION ............................................................................... 49

II.STRUCTURAL SENSOR SURVEILLANCE ............................................. 52

A.SMART SENSOR DESIGN .............................................................. 54

1.Built Environment ........................................................... 55

2.Utilities ............................................................................. 58

3.Public Safety .................................................................... 60

*

Professor of Law, American University Washington College of Law. Thank you to Steve

Bellovin, Marc Blitz, Danielle Citron, Andrew Crespo, David Gray, Stephen Henderson, Orin

Kerr, Mary Leary, Cynthia Lee, Ron Lee, Rebecca Lipman, Wayne Logan, Richard Re, Andrew

Selbst, Katherine Strandburg, Matt Tokson, Kate Weisburd, Jordan Woods, and the University of

Maryland School of Law Legal Theory Workshop participants, the AALS/ABA Criminal Justice

Section workshop, and friends at the Privacy Law Scholars Conference for reading an earlier

version of this Article.

48 IOWA LAW REVIEW [Vol. 106:47

4.City-Wide Application Programming Interface ............ 64

B.SMART SENSOR PRIVACY ............................................................ 67

III.THE FOURTH AMENDMENT & SMART SENSORS IN PUBLIC .............. 70

A.A DIGITAL REASONABLE EXPECTATION OF PRIVACY TEST

IN PUBLIC ................................................................................. 70

1.Reasonable Expectation of Privacy Principles .............. 72

i.Principle #1: Digital is Different .................................. 75

ii.Principle #2: The Court Disfavors Arbitrary and

“Too Permeating” Surveillance ..................................... 76

iii.Principle #3: Aggregating and Permanent

Tracking Technologies Raise Fourth Amendment

Concerns ..................................................................... 77

2.Fourth Amendment Principles for Structural

Surveillance...................................................................... 79

B.THE FOURTH AMENDMENT APPLIED TO SMART SENSORS ............ 79

1.Integrated Data Collection Systems: API ....................... 80

2.Visual Surveillance & Object Recognition .................... 82

3.Public Utilities ................................................................. 84

4.Smart Streetlights ............................................................ 86

C.RESPONSES TO THE REASONABLE EXPECTATION OF PRIVACY

PUZZLE ..................................................................................... 87

1.Public Exposure .............................................................. 87

2.Consent–Assumption of Risk .......................................... 88

3.Type of Data .................................................................... 90

4.Acquisition of Data .......................................................... 90

D.CONCLUSION: REASONABLY SMART EXPECTATIONS OF

PRIVACY IN PUBLIC .................................................................... 91

IV.THE FOURTH AMENDMENT & SMART SENSORS AS TRESPASS

SEARCHES ........................................................................................ 91

V.FOURTH AMENDMENT IN THE DIGITAL CITY: EXCEPTIONS? ........... 95

A.SPECIAL NEEDS EXCEPTION ........................................................ 95

B.REASONABLENESS ...................................................................... 97

VI. A DIGITAL PRIVACY-FOCUSED POSITIVE LAW ................................ 100

A.THE POSITIVE LAW MODEL ...................................................... 102

B.DIGITAL PROPERTY: FOURTH AMENDMENT PROTECTIONS

THROUGH PROPERTY RIGHTS .................................................. 104

C.POSITIVE LAW: FOURTH AMENDMENT PROTECTIONS

THROUGH LAW ....................................................................... 106

D.DIGITAL PRIVACY RIGHTS: FOURTH AMENDMENT

EXPECTATIONS THROUGH COMPUTER CODE ............................. 108

2020] STRUCTURAL SENSOR SURVEILLANCE 49

E.DESIGNING THE “LEGAL LAYER” .............................................. 111

VII. CONCLUSION ................................................................................ 112

I. INTRODUCTION

Sensors are now embedded in the infrastructure of American cities.

Smart roads, smart streetlights, smart homes, and smart electrical grids offer

entirely new means of monitoring citizens living in “smart cities.”1 This

municipal data collection involves state actors surveilling citizens, literally

tagging them, touching them, and tracking them—all the while aggregating

personal data for government purposes over long periods of time.

Unfortunately, and a bit awkwardly, these digital contacts collide with

Fourth Amendment “search”2 principles because the modern Fourth

Amendment turns on issues such as tracking, touch, aggregated personal data

collection, and “too permeating police surveillance.”3 Physical intrusion,4

expectations of privacy,5 and a fear of arbitrary surveillance6 rest at the core

of Fourth Amendment search cases.

This Article asks the question of what happens when the architecture of

a digital future is built on an analog Fourth Amendment framework. Are

smart city sensors unconstitutional because they inadvertently allow for

aggregated government collection of personal data without a probable-cause

search warrant? Will smart cities become Fourth Amendment-free zones with

ubiquitous tracking and no expectations of privacy? Or can design principles

1. See, e.g., BEN GREEN, THE SMART ENOUGH CITY: PUTTING TECHNOLOGY IN ITS PLACE TO

RECLAIM OUR URBAN FUTURE 1–14 (2019).

2. The Fourth Amendment provides that

[t]he right of the people to be secure in their persons, houses, papers, and effects,

against unreasonable searches and seizures, shall not be violated, and no Warrants

shall issue, but upon probable cause, supported by Oath or affirmation, and

particularly describing the place to be searched, and the persons or things to be

seized.

U.S. CONST. amend. IV.

3. Carpenter v. United States, 138 S. Ct. 2206, 2214 (2018) (quoting United States v. Di

Re, 332 U.S. 581, 595 (1948)); see id. at 2211–20.

4. United States v. Jones, 565 U.S. 400, 404–05 (2012) (finding that “[t]he

Government[’s] physically occup[ying] private property for the purpose of obtaining

information” was a search for Fourth Amendment purposes).

5. Katz v. United States, 389 U.S. 347, 361 (1967) (Harlan, J., concurring) (“My

understanding of the rule that has emerged from prior decisions is that there is a twofold

requirement, first that a person have exhibited an actual (subjective) expectation of privacy and,

second, that the expectation be one that society is prepared to recognize as ‘reasonable.’”).

6. See United States v. Martinez-Fuerte, 428 U.S. 543, 554 (1976) (articulating that the

purpose of the Fourth Amendment is to protect against “arbitrary and opp ressive interference by

enforcement officials with the privacy and personal security of individuals”).