CRS R42701 Drones in Domestic Surveillance Operations Fourth Amendment Implications and Legislative Responses

Drones in Domestic Surveillance Operations:
Fourth Amendment Implications and
Legislative Responses

Richard M. Thompson II
Legislative Attorney

April 3, 2013

Congressional Research Service
7-5700
www.crs.gov
R42701
CRS Report for Congress
Prepared for Members and Committees of Congress

Drones in Domestic Surveillance Operations

Summary
The prospect of drone use inside the United States raises far-reaching issues concerning the extent
of government surveillance authority, the value of privacy in the digital age, and the role of
Congress in reconciling these issues.

Drones, or unmanned aerial vehicles (UAVs), are aircraft that can fly without an onboard human
operator. An unmanned aircraft system (UAS) is the entire system, including the aircraft, digital
network, and personnel on the ground. Drones can fly either by remote control or on a
predetermined flight path; can be as small as an insect and as large as a traditional jet; can be
produced more cheaply than traditional aircraft; and can keep operators out of harm’s way. These
unmanned aircraft are most commonly known for their operations overseas in tracking down and
killing suspected members of Al Qaeda and related organizations. In addition to these missions
abroad, drones are being considered for use in domestic surveillance operations to protect the
homeland, assist in crime fighting, disaster relief, immigration control, and environmental
monitoring.

Although relatively few drones are currently flown over U.S. soil, the Federal Aviation
Administration (FAA) predicts that 30,000 drones will fill the nation’s skies in less than 20 years.
Congress has played a large role in this expansion. In February 2012, Congress enacted the FAA
Modernization and Reform Act (P.L. 112-95), which calls for the FAA to accelerate the
integration of unmanned aircraft into the national airspace system by 2015. However, some
Members of Congress and the public fear there are insufficient safeguards in place to ensure that
drones are not used to spy on American citizens and unduly infringe upon their fundamental
privacy. These observers caution that the FAA is primarily charged with ensuring air traffic safety,
and is not adequately prepared to handle the issues of privacy and civil liberties raised by drone
use.

This report assesses the use of drones under the Fourth Amendment right to be free from
unreasonable searches and seizures. The touchstone of the Fourth Amendment is reasonableness.
A reviewing court’s determination of the reasonableness of a drone search would likely be
informed by location of the search, the sophistication of the technology used, and society’s
conception of privacy in an age of rapid technological advancement. While individuals can expect
substantial protections against warrantless government intrusions into their homes, the Fourth
Amendment offers less robust restrictions upon government surveillance occurring in public
places including areas immediately outside the home, such as in driveways or backyards.
Concomitantly, as technology advances, the contours of what is reasonable under the Fourth
Amendment may adjust as people’s expectations of privacy evolve.

In the 113th Congress, several measures have been introduced that would restrict the use of drones
at home. Several of the bills would require law enforcement to obtain a warrant before using
drones for domestic surveillance, subject to several exceptions. Others would establish a regime
under which the drone user must file a data collection statement stating when, where, how the
drone will be used and how the user will minimize the collection of information protected by the
legislation.



Contents
Introduction...................................................................................................................................... 1
Background, Uses, and Drone Technology ............................................................................... 2
Fourth Amendment “Search” Jurisprudence.................................................................................... 4
Privacy in the Home .................................................................................................................. 6
Curtilage and Open Fields ......................................................................................................... 7
Manned Aerial Surveillance ...................................................................................................... 7
Government Tracking ................................................................................................................ 8
Border Searches ....................................................................................................................... 10
Warrants, Suspicionless Searches, and Special Needs ............................................................ 11
Application of Fourth Amendment to Drone Surveillance ............................................................ 12
Location of Search ................................................................................................................... 13
Technology Used ..................................................................................................................... 14
Warrant Requirement and Suspicionless Drone Searches ....................................................... 17
Legislative Proposals in the 113th Congress to Constrain Domestic Use of Drones...................... 18
Preserving Freedom from Unwarranted Surveillance Act of 2013 (H.R. 972) ....................... 18
Preserving American Privacy Act of 2013 (H.R. 637) ............................................................ 18
Drone Aircraft Privacy and Transparency Act of 2013 (H.R. 1262) ....................................... 20
Conclusion ..................................................................................................................................... 21

Contacts
Author Contact Information........................................................................................................... 21



Introduction
The prospect of drone use in domestic surveillance operations has engendered considerable debate
among Americans of various political ideologies.1 Opponents of drone surveillance have complained
that the use of unmanned aircraft on American soil infringes upon fundamental privacy interests and
the ability to freely associate with others.2 Some are specifically concerned about the possibility of
turning military technology inward to surveil American citizens.3 Proponents have responded by
emphasizing their potential benefits, which may include protecting public
safety, patrolling our nation’s borders, and investigating and enforcing The tension between
environmental and criminal law violations.4 security and privacy
interests is not new, but
The tension between security and privacy interests is not new, but has has been heightened by
the explosion of
been heightened by the explosion of surveillance technology in recent surveillance technology in
decades. Police officers who were once relegated to naked eye recent decades.
observations may soon have, or in some cases already possess, the
capability to see through walls or track an individual’s movements from the sky.5 One might
question, then: What is the proper balance between the necessity of the government to keep
people safe and the privacy needs of individuals? As some polls suggest, while the public
supports drone usage in certain circumstances, they are less enthusiastic about using them as part
of routine law enforcement activity.6

1
The term “domestic drone surveillance” as used in this report is designed to cover a wide range of government uses
including, but not limited to, investigating and deterring criminal or regulatory violations; conducting health and safety
inspections; performing search and rescue missions; patrolling the national borders; and conducting environmental
investigations.
2
Letter from Representatives Edward J. Markey and Joe Barton, Co-Chairmen of the Congressional Bi-Partisan
Privacy Caucus, to Michael P. Huerta, Acting Administrator of the Federal Aviation Administration (April 19, 2012)
(“[I]n addition to benefits, there is also the potential for drone technology to enable invasive and pervasive surveillance
without adequate privacy protections.”), available at http://markey.house.gov/sites/markey.house.gov/files/documents/
4-19-12.Letter%20FAA%20Drones%20.pdf; AMERICAN CIVIL LIBERTIES UNION, PROTECTING PRIVACY FROM AERIAL
SURVEILLANCE: RECOMMENDATIONS FOR GOVERNMENT USE OF DRONE AIRCRAFT 1 (2011), available at
https://www.aclu.org/files/assets/protectingprivacyfromaerialsurveillance.pdf.
3
Mark Brunswick, Spies in the sky signal new age of surveillance, STARTRIBUNE (July 22, 2012, 6:26 a.m.), available
at http://www.startribune.com/local/163304886.html?refer=y.
4
Some state and local officials have expressed interest in employment of drones for public safety and law enforcement
purposes. See, e.g., Brianne Carter, Gov. Bob McDonnell supports drones policing Virginia, ABC NEWS (May 30,
2012), available at http://www.wjla.com/articles/2012/05/gov-bob-mcdonnell-supports-drones-policing-virginia-
76464.html; Unmanned Aircraft Systems Within the Homeland: Security Game Changer? Hearing Before the
Subcomm. on Oversight, Investigations, and Management of the H. Comm. on Homeland Sec., 112th Cong. 3 (2012)
(statement of William R. McDaniel, Chief Deputy, Montgomery County Sheriff’s Office, Conroe, TX) (“UAV systems
for public safety agencies are extremely viable, effective, and economical means to enhance the public safety response
to critical incidents.”).
5
The Supreme Court remarked in Kyllo v. United States, 533 U.S. 27, 37 (2001):
The ability to ‘see’ through walls and other opaque barriers is a clear, and scientifically feasible,
goal of law enforcement research and development. The National Law Enforcement and
Corrections Technology Center, a program within the United States Department of Justice, features
on its Internet Website projects that include a ‘Radar-Based Through-the-Wall Surveillance
System,’ ‘Handheld Ultrasound Through the Wall Surveillance,’ and a ‘Radar Flashlight’ that ‘will
enable law officers to detect individuals through interior building walls.’
6
U.S. Supports Some Domestic Drone Use, But Public Registers Concern About Own Privacy 1, Monmouth University
Polling Institute (June 12, 2012), available at http://www.monmouth.edu.

Congressional Research Service 1


The Fourth Amendment to the United States Constitution safeguards Americans’ privacy and
prevents excessive government intrusion by prohibiting “unreasonable searches and seizures.”7
Courts have long grappled with how to apply the text of this 18th century provision to 20th century
technologies. Although the Supreme Court has the final say in the interpretation of the Fourth
Amendment and other constitutional safeguards,8 Congress and, in many cases, the President are
free to institute more stringent restrictions upon government surveillance operations.9

This report first explores the potential uses of drones in the domestic sphere by federal, state, and
local governments. It then surveys current Fourth Amendment jurisprudence, including cases
surrounding privacy in the home, privacy in public spaces, location tracking, manned aerial
surveillance, and those involving the national border. Next, it considers how existing
jurisprudence may inform current and proposed drone uses. It then describes the various
legislative measures introduced in the 113th Congress to address the legal and policy issues
surrounding drones. Finally, it briefly identifies several alternative approaches that may constrain
the potential scope of drone surveillance.

Background, Uses, and Drone Technology
Drones, also known as unmanned aerial vehicles (UAVs), are aircraft that do not carry a human
operator and are capable of flight under remote control or autonomous programming.10 An
unmanned aircraft system (UAS) is the entire system, including the aircraft, digital network, and
personnel on the ground.11 Drones can range from the size of an insect—sometimes called nano
drones or micro UAVs—to the size of a traditional jet.12

Drones are perhaps most commonly recognized from their missions abroad, including to target
and kill suspected members of Al Qaeda and related groups, but they might be used for a variety
of other purposes, including for both commercial and law enforcement activities within the
United States. In fact, the FAA predicted that 30,000 unmanned aircraft could be flying in U.S.
skies in less than 20 years.13 One reason for this expansion has been a push by Congress for a

7
U.S. CONST. amend IV.
8
Cooper v. Aaron, 358 U.S. 1, 18 (1958) (“[Marbury v. Madison] declared the basic principle that the federal judiciary
is supreme in the exposition of the law of the Constitution, and that principle has ever since been respected by this
Court and the Country as a permanent and indispensable feature of our constitutional system.”).
9
In reaction to the Supreme Court’s ruling in United States v. Miller, 425 U.S. 435 (1976), that the privacy of an
individual’s bank records were generally not protected by the Fourth Amendment, Congress enacted the Right to
Financial Privacy Act, P.L. 95-630, 92 Stat. 3697 (codified at 12 U.S.C. §3401-3422), creating a statutory protection
for such records.
10
DEP’T OF DEFENSE, DICTIONARY OF MILITARY AND ASSOCIATED TERMS 331 (2012). Unless expressly mentioned, the
terms “unmanned aerial vehicle,” “UAV,” “unmanned aircraft system,” “UAS,” and “drone” are used interchangeably
in this report.
11
Id.
12
See CRS Report R42136, U.S. Unmanned Aerial Systems, by Jeremiah Gertler, for a description of the various types
of drones currently operated in the United States.
13
FEDERAL AVIATION ADMINISTRATION, FAA AEROSPACE FORECAST: FISCAL YEARS 2010-2030, at 48 (2010), available
at http://www.faa.gov/data_research/aviation/aerospace_forecasts/2010-2030/media/2010%20Forecast%20Doc.pdf.
The FAA has noted that “Federal agencies are planning to increase their use of UAS’s. State and local governments
envision using UAS’s to aid in law enforcement and firefighting. Potential commercial uses are also possible, for
example, in real estate photography or pipeline inspection. UAS’s could perform some manned aircraft missions with
less noise and fewer emissions.” Id.



faster integration of UAVs into U.S. airspace.14 Most recently, as part of the FAA Modernization
and Reform Act of 2012, Congress mandated that the Federal Aviation Administration (FAA)
“develop a comprehensive plan to safely accelerate the integration of civil unmanned aircraft
systems into the national airspace system.”15 This plan shall provide for integration of UAVs by
September 2015.

Drones have been employed domestically by federal, state, and local governments in a range of
circumstances. The Department of Homeland Security (DHS) uses them to police the nation’s
borders to deter unlawful border crossings by unauthorized aliens, criminals, and terrorists, and to
detect and interdict the smuggling of weapons, drugs, and other contraband into the country.16
Within DHS, Customs and Border Protection’s (CBP’s) Office of Air and Marine (OAM) has
flown missions to support federal and state agencies such as the Federal Bureau of Investigation
(FBI), the Department of Defense (DOD), Immigration and Customs Enforcement (ICE), the U.S.
Secret Service, and the Texas Rangers.17 According to a recent disclosure by the FAA, several
local police departments, state and private colleges, and small cities and towns have also received
FAA Certificates of Authorization (COAs) to fly unmanned aircraft domestically.18 Recently, a
police force in North Dakota conducted the nation’s first drone-assisted arrest.19 DHS, in
conjunction with local law enforcement agencies, has been testing drone capabilities in a host of
other situations including detecting radiation, monitoring a hostage situation, tracking a gun
tossed by a fleeing suspect, firefighting, and finding missing persons.20

Currently, drones can be outfitted with high-powered cameras,21 thermal imaging devices,22
license plate readers,23 and laser radar (LADAR).24 In the near future, law enforcement

14
See, e.g., Intelligence Reform and Terrorism Prevention Act of 2004, P.L. 108-458, §5102, 118 Stat. 3638, 3732
(requesting that DHS test the feasibility of using unmanned aircraft to patrol the northern border of the United States).
15
FAA Modernization and Reform Act of 2012, P.L. 112-95, §332, 126 Stat. 11, 73.
16
See CRS Report RS21698, Homeland Security: Unmanned Aerial Vehicles and Border Surveillance, by Chad C.
Haddal and Jeremiah Gertler.
17
The OAM mission is to “protect the American people and the Nation’s critical infrastructure through the coordinated
use of integrated air and marine forces.” DEP’T OF HOMELAND SECURITY, OFFICE OF INSPECTOR GENERAL, CBP’S USE OF
UNMANNED AIRCRAFT SYSTEMS IN THE NATION’S BORDER SECURITY 2 (2012). These forces are used to “detect,
interdict, and prevent acts of terrorism and the unlawful movement of people, illegal drugs, and other contraband
toward or across U.S. borders.” Id.
18
There are over 300 total, including those issued to the following entities: City of Herrington, KS; Cornell University;
Department of Energy Idaho National Laboratory; Eastern Gateway College Community College—Steubenville, OH;
Miami-Dade Police Department; Mississippi Department of Marine Resources; North Little Rock Police Department,
AR; Ogden Police Department, UT; Ohio University; Seattle Police Department; Texas A&M—Texas Engineering
Experiment Station; Texas Department of Public Safety; Texas State University; University of Connecticut; University
of Florida; U.S. Department of Agriculture Agricultural Research Service; Utah State University; Virginia Tech. See
Unmanned Aircraft Systems, Federal Aviation Administration, http://www.faa.gov/about/initiatives/uas/.
19
New age of surveillance, supra note 3.
20
Brian Bennett, Drones Tested as Tools for Police and Firefighters, LOS ANGELES TIMES (August 5, 2012 5:00 A.M.),
http://www.latimes.com/news/nationworld/nation/la-na-drones-testing-20120805,0,6483617.story.
21
The U.S. Army recently acquired a 1.8 gigapixel camera for use on its drones. This camera offers 900 times the
pixels of a 2 megapixel camera found in some cell phones. It can track objects on the ground 65 miles away from an
altitude of 20,000 feet. US Army unveils 1.8 gigapixel camera helicopter drone, BBC NEWS (December 29, 2011 6:11
p.m.), http://www.bbc.com/news/technology-16358851.
22
Infrared cameras, also known as thermal imaging, can see objects through walls based on the relative levels of heat
produced by the objects. See Draganflyer X6, Thermal Infrared Camera, http://www.draganfly.com/uav-helicopter/
draganflyer-x6/features/flir-camera.php.
23
This sensor can recognize and permit drones to track vehicles based on license plate numbers. Customs and Border
(continued...)



organizations might seek to outfit drones with facial recognition or soft biometric recognition,
which can recognize and track individuals based on attributes such as height, age, gender, and
skin color.25 As explained below, the relative sophistication of drones contrasted with traditional
surveillance technology may influence a court’s decision whether domestic drone use is lawful
under the Fourth Amendment.

Fourth Amendment “Search” Jurisprudence
The Fourth Amendment’s story is one of continuity and change. Core values such as privacy and
protection from excessive and arbitrary government intrusion are always within its sweep. A
continuing question, though, is how the demands of its protection apply to an ever-changing
society in which new and pervasive forms of technology are increasingly common. Although
there are numerous rules and exceptions throughout the Supreme Court’s Fourth Amendment
jurisprudence, this section will explore those most pertinent to domestic drone use.

In short, the Fourth Amendment regulates when, where, and how the government may conduct
searches and seizures. The Amendment provides, in relevant part: “The right of the people to be
secure in their persons, houses, papers, and effects, against unreasonable searches and seizures,
shall not be violated[.]”26 The Fourth Amendment does not apply to all government acts, but only
to those that constitute a search. So when does government monitoring constitute a Fourth
Amendment “search” for which a warrant is generally required? Initially, courts’ assessment
focused on the specific area being investigated. Consider the 1928 case Olmstead v. United
States.27 There, the Supreme Court held that police wiretaps of the defendant’s home telephone
did not constitute a Fourth Amendment search because the police did not trespass onto
Olmstead’s property to intercept his conversation.28 The Court’s thinking at the time was that if
the person’s home, tangible property, or papers were not physically invaded, then no search in the
constitutional sense occurred. Almost 40 years later, the Court shifted focus from property to
privacy interests.29 In Katz v. United States, decided in 1967, the Court held that an FBI agent’s
use of a bug to listen to the private conversations of Mr. Katz while in a telephone booth violated
his Fourth Amendment rights.30 Although he was in a public telephone booth and there was no
physical invasion, the Court noted that what a person “seeks to preserve private, even in an area
accessible to the public, may be constitutionally protected.”31 One of the modern Fourth

(...continued)
Protection Today, Unmanned Aerial Vehicles Support Border Security (July 2004), http://www.cbp.gov/xp/
CustomsToday/2004/Aug/other/aerial_vehicles.xml.
24
This sensor produces three-dimensional images, and has the capability to see through trees and foliage. U.S. ARMY,
UAS CENTER FOR EXCELLENCE, “EYES OF THE ARMY” US ARMY ROADMAP FOR UNMANNED AIRCRAFT SYSTEMS 2010-
2035, at 83 (2010).
25
See Clay Dillow, Army Developing Drones that Can Recognize Your Face from a Distance, POPSCI (September 28,
2011), 5:01 p.m.), available at http://www.popsci.com/technology/article/2011-09/army-wants-drones-can-recognize-
your-face-and-read-your-mind.
26
27
Olmstead v. United States, 277 U.S. 438, 466 (1928).
28
Id.
29
Katz v. United States, 389 U.S. 347, 351 (1967).
30
Id. at 359.
31
Id. at 351.



Amendment tests relied upon by courts in assessing whether government monitoring constitutes a
“search” derives from Justice Harlan’s concurrence in Katz. It considers whether the person has a
subjective expectation of privacy in the area to be searched and whether society is prepared to
deem that expectation reasonable.32

Although the Court said in Katz that the Fourth Amendment “protects people not places,”33
Justice Harlan noted that determining what “protection it affords people ... requires reference to a
‘place.’”34 And as Justice Scalia observed when writing for a majority of the Court in United
States v. Jones, a Fourth Amendment search occurs, “at a minimum,” where “the Government
obtains information by physically intruding on a constitutionally protected area.”35 The majority
in Jones indicated that the reasonable expectation of privacy test was never intended to replace
the property-based approach used in earlier cases, but merely augment it.36 So where do
individuals enjoy the most Fourth Amendment protection? The least? Why does the location
dictate the level of protection? And how does technology affect society’s expectation of privacy?

When analyzing domestic drone use under the Fourth Amendment, a reviewing court may be
informed by cases surrounding privacy in the home, privacy in public spaces, location tracking,
manned aerial surveillance, those involving the national border, and warrantless searches under
the special needs doctrine.

32
Id. at 361 (Harlan, J., concurring).
33
Id. at 351.
34
Id. at 361 (Harlan, J., concurring); see also Oliver v. United States, 466 U.S. 170 (1984).
We have frequently acknowledged that privacy interests are not coterminous with property rights.
E. g., United States v. Salvucci, 448 U.S. 83, 91 (1980). However, because “property rights reflect
society’s explicit recognition of a person’s authority to act as he wishes in certain areas, [they]
should be considered in determining whether an individual’s expectations of privacy are
reasonable.” Rakas v. Illinois, 439 U.S. 128, 153 (1978) (Powell, J., concurring). Indeed, the Court
has suggested that, insofar as “[one] of the main rights attaching to property is the right to exclude
others, ... one who owns or lawfully possesses or controls property will in all likelihood have a
legitimate expectation of privacy by virtue of this right to exclude.” Id., at 144, n. 12.
Oliver, 466 U.S. at 189-90.
35
United States v. Jones, 132 S. Ct. 945, 950 n.3 (2012).
36
Id.



Privacy in the Home
The home has always held a central place in American life, and remains the area accorded the
greatest Fourth Amendment protection.37 The Fourth Amendment protects this zone of privacy by
ensuring that “the right of the people to be secure in their ... houses ... against unreasonable search
and seizure, shall not be violated[.]”38 In most instances, the Supreme
Court has rigorously adhered to this safeguard.39 For instance, although “The right of the people to
police officers may make a warrantless arrest of an individual for a be secure in their ... houses
... against unreasonable
felony offense committed in public,40 they may not step inside his home search and seizure, shall not
41
without a warrant, barring any recognized exception. be violated[.]” U.S. CONST.
amend IV.
In addition to a physical entry and search of the home, police are
likewise prohibited from using certain technology to pierce this zone of privacy. In Kyllo v.
United States, government agents used a thermal-imaging device to determine heat patterns inside
the home of Danny Kyllo.42 The Court began with the presumption that a warrantless search of a
home is unreasonable.43 Ultimately, the Court protected this “realm of guaranteed privacy” by
holding that obtaining information about the inside of a home that could not otherwise be
obtained except by entering the home, through the use of technology not in “general public use,”
is a “search” covered by the Fourth Amendment.44

The home, however, does not provide an absolute shield against government surveillance. As
Justice Harlan emphasized in Katz, “[A] man’s home is, for most purposes, a place where he
expects privacy, but objects, activities, or statements that he exposes to the plain view of outsiders
are not ‘protected’ because no intention to keep them to himself has been exhibited.” Indeed, in
certain instances, police may use their natural senses to conduct warrantless searches of the inside
of a home.45 To fall under this exception—known as the “plain view” doctrine—the police must
be in a lawful vantage point when they conduct the surveillance, and the incriminating nature of
the evidence must be readily apparent.46

37
DANIEL SOLOVE, UNDERSTANDING PRIVACY 59 (2008).
38
39
Silverman v. United States, 365 U.S. 505, 512 (1961) (“At the very core stands the right of a man to retreat into his
own home and be free from unreasonable government intrusion.”).
40
United States v. Watson, 423 U.S. 411 (1976).
41
Payton v. New York, 445 U.S. 573, 603 (1980). This protection not only covers traditional houses, but apartments,
Clinton v. Virginia, 377 U.S 158 (1963), and motel rooms, Stoner v. California, 376 U.S. 483 (1964).
42
Kyllo v. United States, 533 U.S. 27, 29-30 (2001).
43
Id. at 31.
44
Id. at 34.
45
In one case, police observation of marijuana plants through a crack in the house’s siding did not constitute an
unlawful search. United States v. Hammett, 236 F.3d 1054, 1061 (9th Cir. 2001). In another, the court held that the
police officer’s observation of contraband through the front dining room window was not unlawful. United States v.
Taylor, 90 F.3d 903, 909 (4th Cir. 1996).
46
Coolidge v. New Hampshire, 403 U.S. 443, 466 (1971).



Curtilage and Open Fields
Once an individual moves from the confines of the home, he is entitled to different Fourth
Amendment considerations. Depending on a host of varying factors, areas outside of the home
may be considered “curtilage” or “open fields.”47 The curtilage is the area immediately
surrounding the home—an area the Court has granted similar protections as the inside of the
home.48 To determine if an area is curtilage, a court will look at how close the area is to the home;
whether the area is within a fence surrounding the home; how the area is used; and whether the
area is protected from observation by passersby.49 Although an area may be deemed curtilage—as
with the home—it is not veiled with unconditional constitutional protection. As the Court noted in
one aerial surveillance case:

The Fourth Amendment protection of the home has never been extended to require law
enforcement officers to shield their eyes when passing by a home on public thoroughfares.
Nor does the mere fact that an individual has taken measures to restrict some views of his
activities preclude an officer’s observations from a public vantage point where he has a right
to be and which renders the activities clearly visible.50

On the other hand, the area outside the curtilage is sometimes considered “open fields,” which
“do not provide the setting for those intimate activities that the Amendment is intended to shelter
from governmental interference or surveillance,”51 and thus are not given similar Fourth
Amendment protections. Differentiating between the two is no easy task. In one case, for
example, the Ninth Circuit Court of Appeals determined that the defendant’s driveway was not
curtilage as he had taken no affirmative steps to block it from observation by passers-by.52
Furthermore, in the fly-over cases discussed infra, the Supreme Court has permitted similar
searches in both open fields and the curtilage, to some extent eliminating any constitutional
difference between the two.

Manned Aerial Surveillance
In a series of cases that provide the closest analogy to UAVs, the Supreme Court addressed the
use of manned aircraft to conduct domestic surveillance over residential and industrial areas. In
each, the Court held that the fly-over at issue was not a search prohibited by the Fourth
Amendment, as the areas surveilled were open to public view.

47
United States v. Hester, 365 U.S 57 (1924) (distinguishing between the doctrines of curtilage and open fields).
48
The Court has defined curtilage as “the area to which extends the intimate activity associated with the ‘sanctity of a
man’s home and the privacies of life.’” Oliver v. United States, 466 U.S. 170, 180 (1984) (quoting Boyd v. United
States, 116 U.S. 616, 630 (1886)).
49
United States v. Dunn, 480 U.S. 294, 301 (1987).
50
California v. Ciraolo, 476 U.S. 207, 213 (1986).
51
Dow Chemical Co. v. United States, 476 U.S. 227, 234-35 (1986) (quoting Oliver, 466 U.S. at 179).
52
Maisano v. Welcher, 940 F.2d 499 (9th Cir. 1991).



In California v. Ciraolo, police received a tip that an individual was growing marijuana in his
backyard next to his suburban home.54 Because two fences blocked their view of the yard, officers
flew a fixed-wing aircraft at an altitude of 1,000 feet over the property to conduct a visual inspection.
From this vantage point, the officers readily identified with the naked eye marijuana plants growing
in the defendant’s yard. The Court held that the defendant’s expectation of privacy in the area
immediately surrounding his home was not reasonable, since “what a person knowingly exposes to
the public ... is not a subject of Fourth Amendment protection.”55 “Any
member of the public flying in this airspace who glanced down could have “What a person knowingly
seen everything these officers observed,” the Court remarked.56 Much exposes to the public ... is
not a subject of Fourth
weight was placed on the fact that the plane was at all times in navigable Amendment protection.”53
airspace as defined by federal statute.57

Similarly, in Florida v. Riley, local police received a tip that an individual was growing marijuana
in a greenhouse located 10 to 20 feet away from his mobile home.58 The officers could not see the
contents of the greenhouse from the ground, so they flew a helicopter over the defendant’s
backyard at an altitude of 400 feet. While overhead, an officer saw marijuana plants through a
crack in the greenhouse roof. Because the helicopter, like the plane in Ciraolo, was in navigable
airspace—where any member of the public could have flown—the Court did not consider this a
search for which a warrant was required.59

In the final case of the series, Dow Chemical v. United States, the Court was asked whether a
theory of “industrial curtilage” would prevent a government agency from conducting aerial
surveillance over a 2,000-acre commercial plant.60 There, after Dow Chemical Co. refused access
to the Environmental Protection Agency (EPA), the EPA hired a commercial aerial photographer
to take photos of the facility using a precision aerial mapping camera. Having ruled out the
argument that the areas surrounding an industrial complex are entitled to the same protection as
similar areas surrounding a home, the Court concluded that photographing the plant from
navigable airspace was not a search.61

Government Tracking
Like the aerial surveillance cases, individuals have reduced—and in some contexts no—Fourth
Amendment protection from government tracking of their travel in public places. This has
permitted the government to conduct warrantless tracking of a vehicle’s movements while
traveling on public streets. However, once people enter a private residence, the tracking must

53
Ciraolo, 476 U.S. at 213.
54
Id. at 207.
55
Id. at 213.
56
Id. at 213-214. It should be noted that although the police did take photographs with a 35-millimeter camera, the
warrant relied on naked-eye observations and not the photographs. Thus, the holding was based on the naked-eye
observations, unaided by the camera.
57
Id. at 213 (citing 49 U.S.C. §1304).
58
Florida v. Riley, 488 U.S. 445, 448 (1989).
59
Id.
60
Dow Chemical Co., 476 U.S. 227.
61
Id. at 239



cease. Also, using technology to perform pervasive tracking might not meet Fourth Amendment
muster.

Consider, for example, these two government tracking cases, United States v. Knotts and United
States v. Karo.62 In both cases, the government hid a location monitoring device in an item that
was then given to the suspects. In Knotts, the police tracked the suspect’s movements solely while
traveling on public roadways.63 The Court held that people have no reasonable expectation of
privacy in their movements on public streets. As such, no Fourth Amendment search occurred,
thus no warrant was required. By contrast, in Karo, the police tracked a beeper device on public
streets and while the beeper was in a private residence—a “location not open to visual
surveillance.”64 “Indiscriminate monitoring of property that has been withdrawn from public
view,” the Court declared, “would present far too serious a threat to privacy interests in the home
to escape entirely some sort of Fourth Amendment oversight.”65 The Court held the search
unlawful.

Although surveillance in public is generally not considered a search, pervasive tracking may cross
the line. Take, for instance, the Supreme Court’s recent decision in the GPS tracking case United
States v. Jones.66 In that case, the Court held that the attachment and monthlong tracking of a GPS
device on an individual’s vehicle constituted a trespass, and hence a Fourth Amendment search.67
The Court grounded its decision in the property-based approach to assessing what constitutes a
“search” under the Fourth Amendment, which had been more prevalent in the late 19th and early
20th century cases involving relatively unsophisticated technology.

The Court’s focus on whether the attachment of a tracking device constitutes a trespass triggering
Fourth Amendment protections is not necessarily applicable to drone surveillance. However, in
two separate concurring opinions that together made up five members of the Court, an alternative
framework was proposed that may have more far-reaching implications for the domestic use of
UAVs.

Justice Alito, concurring in the Court’s judgment, and joined by Justices Ginsburg, Breyer, and
Kagan, would have held that “the use of longer term GPS monitoring in investigations of most
offenses impinges on expectations of privacy. For such offenses, society’s
expectation has been that law enforcement agents and others would not— Tracking an individual for
an extended period
and indeed, in the main, simply could not—secretly monitor and catalogue
“reflects a wealth of detail
every single movement of an individual’s car for a very long period.” about her familial, political,
Justice Sotomayor, joining the controlling opinion in Jones, but also professional, religious, and
concurring separately, noted that although following people for a short sexual associations.”68
period of time conveys little information about them, tracking an

62
United States v. Knotts, 460 U.S. 276 (1983); United States v. Karo, 468 U.S. 705 (1984).
63
Knotts, 460 U.S. at 279. The Court reiterated that its analysis was based on the fact that the beeper was tracked
within the vicinity of a home, not actually in the home. Id
64
Karo, 468 U.S. at 714.
65
Id. at 715.
66
United States v. Jones, 132 S. Ct. 945 (2012).
67
Id. at 949. See generally CRS Report R42511, United States v. Jones: GPS Monitoring, Property, and Privacy, by
Richard M. Thompson II.
68
Jones, 132 S. Ct. at 955 (Sotomayor, J., concurring).



individual for an extended period “reflects a wealth of detail about her familial, political,
professional, religious, and sexual associations.”69 Thus, the length of time an individual is kept under
surveillance and the breadth of data collected through such surveillance may inform a reviewing
court whether a particular surveillance practice constitutes a Fourth Amendment search.70

Border Searches
Even more so than surveillance of public places generally, law enforcement agencies are granted
significant deference to conduct surveillance at or near American borders. The federal
government has a significant interest in protecting American borders from crossings by persons
attempting to enter unlawfully, drug trafficking, and, perhaps most importantly, the transit of
weapons and persons seeking to do harm to American people and infrastructure.

Congress has granted federal law enforcement agencies significant search powers at the border.
Section 287 of the Immigration and Nationality Act (INA), codified at 8 U.S.C. Section 1357,
authorizes immigration officers to conduct warrantless searches of any vessel within a reasonable
distance from the United States border and any vehicle within 25 miles from a border for the
“purpose of patrolling the border to prevent the illegal entry of aliens into the United States.”71
Similarly, 19 U.S.C. Section 482 authorizes customs officers to search vehicles and persons on
which or whom they have reasonable cause to believe are carrying goods unlawfully into the
United States.72

The Supreme Court has likewise acknowledged this federal interest in the borders, observing that
“[t]he Government’s interest in preventing the entry of unwanted persons and effects is at its
zenith at the international border.”73 Again, the touchstone in every Fourth Amendment case is
whether the search is reasonable.74 The Court observed in United States v. Montoya De
Hernandez that “the Fourth Amendment balance of reasonableness is qualitatively different at the
international border.”75 “Routine searches,” the Court continued, “are not subject to any
requirement of reasonable suspicion, probable cause, or warrant.”76 “Routine” searches have
included pat downs for weapons or contraband,77 the use of drug sniffing dogs,78 and the

69
Id.
70
Although the two concurring opinions in Jones arguably do not constitute binding precedent, lower courts have
combined them as a possible alternative holding. See United States v. Hanna, No. 11-20678-CR, 2012 WL 279435, at
*3 (S.D. Fla. Jan. 3, 2012) (analyzing the issue of Fourth Amendment standing to contest GPS surveillance under both
the trespass theory and Katz’s privacy test); State v. Zahn, No. 25584, 2012 WL 862707 (S.D. Mar. 14, 2012) (holding
that both the trespass approach and the mosaic theory can apply to GPS tracking); but see United States v. Bradshaw,
No. 1:11-CR-257, 2012 WL 774964 (N.D. Ohio Mar. 8, 2012) (noting that the Jones majority did not adopt the mosaic
theory).
71
8 U.S.C. 1357.
72
19 U.S.C. §482. In the 112th Congress, the House of Representatives introduced H.R. 1505, which would enlarge
CBP’s authority to secure U.S. borders on federal land. H.R. 1505; see also John S. Adams, Border bill would expand
Homeland Security powers, USA TODAY (September 26, 2011).
73
United States v. Flores-Montano, 541 U.S. 149, 152 (2004).
74
Cady v. Dombrowski, 413 U.S. 433, 439 (1973).
75
United States v. Montoya De Hernandez, 473 U.S. 531, 538 (1985).
76
Id.
77
United States v. Beras, 183 F.3d 22, 24 (1st Cir. 1999) (ruling that pat down of defendant’s legs was routine search).
78
United States v. Kelly, 302 F.3d 291, 294-95 (5th Cir. 2002).



inspection of luggage.79 By contrast, “non-routine” searches are those that go beyond a limited
intrusion, and require the government official to have (at a minimum) “reasonable suspicion” of
wrongdoing.80 Prolonged detentions,81 strip searches,82 and body cavity searches83 have all been
considered non-routine searches.

Unlike searches directly at the border, the Court has shown more reticence in granting law
enforcement unfettered discretion to conduct searches near, but not directly at, the border. In
Almeida-Sanchez v. United States, the defendant’s vehicle was stopped and searched by U.S.
Border Patrol agents 25 miles north of the U.S.-Mexico border.84 The agents had neither a warrant
nor probable cause, nor even reasonable suspicion, to conduct the search. The government argued
that the search was permissible under Section 287 of the Immigration and Nationality Act. A
federal statute, the Court noted, cannot trump the Constitution. The Court refused to permit this
suspicionless search, as it was conducted neither at the border nor at its “functional equivalent.”85

Warrants, Suspicionless Searches, and Special Needs
The baseline rule in Fourth Amendment cases is that police must obtain a warrant to search an
individual or their property in all but a few limited instances.86 This rule ensures that an
independent judicial officer, rather than a police officer in the field, is determining whether there
is probable cause to conduct a search or seizure.87 Over time, however, the Court has loosened
this warrant requirement in instances where a strict showing of individualized suspicion of
probable cause would hinder the government from addressing health and safety concerns.88 In
two lines of overlapping cases—administrative searches and “special needs” cases—the Court
has balanced the individual’s privacy interest against the government’s interest to determine if a

79
United States v. Okafor, 285 F.3d 842 (9th Cir. 2002).
80
Montoya De Hernandez, 473 U.S. at 541.
81
Id.
82
United States v. Asbury, 586 F.2d 973, 975 (1978).
83
United States v. Ogberaha, 771 F.2d 655, 657 (2d Cir. 1985).
84
Almeida-Sanchez v. United States, 413 U.S. 266, 267-68 (1973).
85
Id. at 272-73 (“For example, searches at an established station near the border, at a point marking the confluence of
two or more roads that extend from the border, might be functional equivalents from border searches. For another
example, a search of the passengers and cargo of an airplane arriving at a St. Louis airport after a nonstop flight from
Mexico would clearly be the functional equivalent of a border search.”). Like Almeida-Sanchez, Border Patrol agents in
United States v. Brignoni-Ponce stopped an individual’s vehicle as part of a roving patrol solely because the occupants
appeared to be of Mexican descent, with no proof of illegal activity. United States v. Brignoni-Ponce, 422 U.S. 873,
874-75 (1975). Again, the Court struck down this practice of suspicionless stops, remarking that “[i]n the context of
border area stops, the reasonableness requirement of the Fourth Amendment demands something more than the broad
and unlimited discretion sought by the Government. Roads near the border carry not only aliens seeking to enter the
country illegally, but a large volume of legitimate traffic as well.” Id. at 882.
86
Mincey v. Arizona, 437 U.S. 385, 390 (1978) (citation omitted).
87
Johnson v. Untied States, 333 U.S. 10, 14 (1948) (“The right of officers to thrust themselves into a home is also a
grave concern, not only to the individual but to a society which chooses to dwell in reasonable security and freedom
from surveillance. When the right of privacy must reasonably yield to the right of search is, as a rule, to be decided by a
judicial officer, not by a policeman or government enforcement agent.”). Probable cause is found when, looking at the
“totality-of-the-circumstances” there “is a fair probability that contraband or evidence of a crime will be found in a
particular place.” Illinois v. Gates, 462 U.S. 213, 238 (1983).
88
Eve Brensike Primus, Disentangling Administrative Searches, 111 COLUM. L. REV. 254, 256 (2011).



warrant or any individualized suspicion is required.89 These two theories permit law enforcement
to conduct dragnet searches in certain instances.

Suspicionless general searches are ones “in which the government searches or seizes every
person, place, or thing in a specific location or involved in a specific activity based only on a
showing of a generalized government interest.”90 Suspicionless searches have been conducted at
the national border,91 private businesses,92 and police roadblocks.93 In the roadblock cases, the
Court has balanced the government’s interest against the individual’s privacy interest to determine
whether police may stop and question drivers without a warrant or any suspicion of criminal
wrongdoing. In Michigan Dep’t of State Police v. Sitz, the Court upheld the suspicionless stopping
and examination of drivers for intoxication at sobriety checkpoints.94 The Court reasoned that the
high incidence of drunk driving balanced against the minimal intrusion on drivers permitted
suspicionless checkpoints. In City of Indianapolis v. Edmund, however, law enforcement was not
permitted to set up a drug interdiction checkpoint.95 The Court held that searches such as this
violated the Fourth Amendment when their “primary purpose” is “to uncover evidence of
ordinary criminal wrongdoing.”96 Justice O’Connor observed that if this type of roadblock were
allowed “the Fourth Amendment would do little to prevent such intrusions from becoming a
routine part of American life.”97

Application of Fourth Amendment to Drone
Surveillance
As evidenced by the foregoing, the constitutionality of domestic drone surveillance may depend
upon the context in which such surveillance takes place. Whether a targeted individual is at home,
in his backyard, in the public square, or near a national border will play a large role in
determining whether he is entitled to privacy. Equally important is the sophistication of the
technology used by law enforcement and the duration of the surveillance. Both of these factors
will likely inform a reviewing court’s reasoning as to whether the government’s surveillance
constitutes an unreasonable search in violation of the Fourth Amendment.

89
Nat’l Treasury Employees Union v. Von Raab, 489 U.S. 656, 665-66 (1989).
90
Primus, supra note 88, at 263.
91
United States v. Martinez-Fuerte, 428 U.S. 543, 566 (1976).
92
United States v. Biswell, 406 U.S 311, 317 (inspection of gun dealer’s storeroom) (“We have little difficulty in
concluding that where, as here, regulatory inspections further urgent federal interest, and the possibilities of abuse and
the threat to privacy are not of impressive dimensions, the inspection may proceed without a warrant where specifically
authorized by statute.”).
93
Mich. Dep’t of State Police v. Sitz, 496 U.S. 444, 455 (1990).
94
Id. at 455.
95
City of Indianapolis v. Edmund, 531 U.S. 32 (2000).
96
Id. at 42.
97
Id.



Location of Search
Based on existing case law, it is reasonable to assume that surveillance of an individual while in
his home—an area accorded the greatest Fourth Amendment protection—using technology not in
general public use would be an unlawful search absent a search warrant. The Supreme Court in
Kyllo was particularly concerned about law enforcement’s use of powerful equipment to peer
inside an individual’s home. Currently, UAVs carry high-megapixel cameras and thermal
imaging, and will soon have the capacity to see through walls and ceilings.98 These technologies
are not generally available to the public, and under current jurisprudence, their use by law
enforcement would probably constitute a search covered by the Fourth Amendment. However, the
use of low-powered cameras or other unsophisticated technology to view people and objects in
plain view while in their home might not trigger Fourth Amendment protections. The rationale for
this notion is that officers are not required to avert their eyes when they see illegal activity in
plain view, especially when the subject of the search has taken no affirmative efforts to hide their
activity from public view.

Moving beyond the home, it is unclear whether circumstances exist in which the area
immediately surrounding the home—for instance, a backyard, a swimming pool, a deck, or a
porch—would receive similar protections as the interior of the home if surveilled by drones or
other aerial vehicles.99 Although the Supreme Court has recited on many occasions that a person
located in a home’s curtilage is accorded similar privacy protections as when inside the home, the
aerial surveillance cases arguably constitute an exception to this general principle. In the two
aerial cases, Riley and Ciraolo, the area surveilled was within close proximity of the home, yet
the police surveillance at altitudes of 400 and 1,000 feet were not considered a search.

Based on the aerial surveillance cases, it may be reasonable to presume a warrant would not be
required (nor, perhaps, any suspicion, for that matter) to conduct drone surveillance of most
public places for a relatively short period of time. The Supreme Court remarked in Ciraolo that
the “Fourth Amendment simply does not require the police traveling in the public airways at
[1,000 feet] to obtain a warrant to observe what is visible to the naked eye.”100 However, the
rarity of drone flights may distinguish their use from surveillance by the piloted aircraft used in
the three aerial cases decided by the Court. All three of these cases were premised on the fact that
each aircraft was flying in navigable airspace, and that these flights were not “sufficiently rare” to
provide a reasonable expectation of privacy in the area to be searched. To this point, Justice White
remarked in Riley that “there is nothing in the record or before us to suggest that helicopters
flying at 400 feet are sufficiently rare in this country to lend substance to respondent’s claim that
he reasonably anticipated that his greenhouse would not be subject to observation from that
altitude.”101 Presently, use of UAVs in U.S. airspace is considerably less common. The FAA has
issued only approximately 300 licenses for drone use in U.S. airspace.102 The general public

98
EYES OF THE ARMY, supra note 24.
99
See generally, Paul McBride, Beyond Orwell: The Application of Unmanned Aircraft Systems in Domestic
Surveillance Operations, 74 J. Air. L. & Com. 627, 655-56 (“This implies that although the curtilage does not benefit
from the absolute protection afforded to the interior of the home, there is a close relationship between the two, and that
technology directed at the home and its curtilage will be subjected to a more skeptical analysis than would be applied in
a case involving open fields or industrial areas.”).
100
California v. Ciraolo, 476 U.S. 207, 215 (1986).
101
Florida v. Riley, 488 U.S. 445, 451-52 (1989).
102
Federal Aviation Administration, supra note 18.



would likely find it exceedingly unusual for a drone to fly over their homes taking surveillance
photographs. This rarity might factor into a reviewing court’s determination of whether
individuals have a legitimate expectation of privacy from various forms of drone surveillance
while in a public place.103

The federal government’s authority to use unmanned aircraft is undoubtedly at its maximum near
U.S. borders. One of the federal government’s only affirmative duties is to protect citizens from
external harm.104 This includes securing the borders. The Court has hesitated from interfering
with the performance of this duty, and it would in all likelihood demonstrate the same deference
when it comes to the use of UAVs. Moreover, the Supreme Court’s rulings in border cases have
all involved active searches—either a physical search of a vehicle or stopping and questioning a
vehicle’s passenger. Surveillance by UAVs, on the other hand, may be considered more passive
and therefore may be even less likely to run afoul of Fourth Amendment requirements. Drone
surveillance does not require any physical manipulation of a person or his things. UAVs also do
not require the seizure of a person for any period of time (though drone surveillance may lead to
law enforcement physically apprehending a person who is seen engaging in suspected illegal
activity). However, the Court has shown some reticence about giving law enforcement carte
blanche search power at the border. Roving vehicle patrols and indiscriminate searches in
Almeida-Sanchez v. United States and United States v. Brignoni-Ponce were deemed
unconstitutional.105 It is unclear whether this reticence would extend to drone surveillance along
the border if it were to become significantly widespread.

Technology Used
Like location, the technology used by UAVs may be a decisive factor considered by courts in
determining whether individuals have a legitimate expectation of privacy in the object or area of
the challenged drone search. Technological developments make it increasingly easy to share and
acquire personal information about others, oftentimes without their direct knowledge or consent.
As surveillance technology advances and becomes ever-present in Americans’ lives, people’s
conception of privacy may tend to oscillate. Justice Scalia, writing for the majority in Kyllo v.
United States, remarked on this trend:

It would be foolish to contend that the degree of privacy secured to citizens by the Fourth
Amendment has been entirely unaffected by the advance of technology. For example, ... the
technology enabling human flight has exposed to public view (and hence, we have said, to
official observation) uncovered portions of the house and its curtilage that once were private.
The question we confront today is what limits there are upon this power of technology to
shrink the realm of guaranteed privacy.106

Justice Alito, joined by three other Justices in his United States v. Jones concurrence, likewise
observed:

103
Ciraolo, 476 U.S. at 212. However, in determining society’s privacy expectations, a reviewing court might also take
into consideration the proliferation of aerial mapping such as Google Maps and Google Earth conducted by private
actors. See generally Google Maps, Street View, http://www.google.com/streetview.
104
U.S. CONST. art. IV, §4 (“The United States shall guarantee to every State in this Union a Republican Form of
Government, and shall protect each of them against Invasion[.]”).
105
Almeida-Sanchez v. United States, 413 U.S. 266 (1973); United States v. Brignoni-Ponce, 422 U.S. 873 (1975).
106
Kyllo v. United States, 533 U.S. 27, 33-34 (2001).



The Katz test rests on the assumption that this hypothetical reasonable person has a well-
developed and stable set of privacy expectations. But technology can change those
expectations. Dramatic technological change may lead to periods in which popular
expectations are in flux and may ultimately produce significant changes in popular attitudes.
New technology may provide increased convenience or security at the expense of privacy,
and many people may find the tradeoff worthwhile. And even if the public does not welcome
the diminution of privacy that new technology entails, they may eventually reconcile
themselves to this development as inevitable.107

The crucial question, then, is whether drones have the potential to be significantly more invasive
than traditional surveillance technologies such as manned aircraft or low-powered cameras—
technologies that have been upheld in previous cases. In this vein, some have asked whether
using sophisticated digital platforms on a drone is any different from attaching the same
instrument to a lamppost or traditional aircraft.108 Take, for example, the tracking of license
plates. Currently, many states and municipalities employ automatic license plate readers
(ALPRs), which are usually mounted on police vehicles or stationary objects along the streets, to
take a snapshot of a license plate as a car drives by, and store this information in a large database
for possible later use by law enforcement.109 It is alleged that these devices can be used to track a
person’s movements when police aggregate the data from a multitude of ALPR stations.110 A
majority of the reviewing federal circuit courts have held that a person has no reasonable
expectation of privacy in his license plate number.111

However, it appears that no federal court has addressed the constitutionality of the use of ALPRs
(whether attached to a drone, manned vehicle, or a stationary device), as opposed to plate
numbers collected by a human observer. Nonetheless, the question remains whether attaching an
ALPR—or any similar sophisticated technology—to a drone would alter the constitutionality of
its use by law enforcement. Some say yes, arguing that the sophistication of drone technology in
and of itself “present[s] a unique threat to privacy.”112 Drones are smaller, can fly longer, and can
be built more cheaply than traditional aircraft. For instance, defense firm Lockheed Martin’s
Stalker—a small, electrically powered drone—can be recharged from the ground using a laser.113
It now has a flight time of more than 48 hours. As this technology advances, it is reported that

107
United States v. Jones, 132 S. Ct. 945, 962 (2012) (Alito, J., concurring).
108
Stanford Law Review Symposium, Drones—Privacy Paradox: Privacy and its Conflicting Values (February 2,
2012), http://cyberlaw.stanford.edu/multimedia/drones-privacy-paradox-privacy-and-its-conflicting-values-video.
109
ACLU Seeks Details on Automatic License Plate Readers in Massive Nationwide Request, AMERICAN CIVIL
LIBERTIES UNION (July 31, 2012), http://www.aclu.org/technology-and-liberty/aclu-seeks-details-automatic-license-
plate-readers-massive-nationwide-reque-4.
110
Id.
111
See, e.g., Olabisiomotosho v. City of Houston, 185 F.3d 521, 529 (5th Cir. 1999) (“A motorist has no privacy interest
in her license plate number. Like the area outside the cartilage [sic] of a dwelling, a car’s license plate number is
constantly open to the plain view of passersby.”) (internal citation and quotation marks omitted); United States v.
Ellison, 462 F.3d 557, 562 (6th Cir. 2006) (“No argument can be made that a motorist seeks to keep the information on
his license plate private. The very purpose of a license plate number, like that of a Vehicle Identification Number, is to
provide identifying information to law enforcement officials and others.”); United States v. Castaneda, 494 F.3d 1146,
1151 (9th Cir. 2007); United States v. Walraven, 892 F.2d 972, 974 (10th 1989).
112
Using Unmanned Aircraft Systems Within the Homeland: Security Game Changer? Hearing Before the Subcomm.
on Oversight, Investigations, and Management of the H. Comm. on Homeland Sec., 112th Cong. 3 (2012) (statement of
Amie Stepanovich, Counsel, Electronic Privacy Information Center).
113
Mark Brown, Lockheed uses ground-based laser to recharge drone mid-flight, WIRED (July 12, 2012), available at
http://www.wired.co.uk/news/archive/2012-07/12/lockheed-lasers.



some drones could theoretically “stay in the air forever.”114 Unlike a stationary license plate
tracker or video camera, drones can lock on a target’s every move for days, and possibly weeks
and months. This ability to closely monitor an individual’s movements with pinpoint accuracy
may raise more significant constitutional concerns than some other types of surveillance
technology.

Furthermore, the technology and sophistication of drones may mark a considerable departure
from the traditional technologies used in the three manned aerial surveillance cases decided by
the Supreme Court. First, all three holdings in Ciraolo, Riley, and Dow Chemical were premised
on naked-eye searches. Chief Justice Burger remarked in Dow Chemical: “It may well be, as the
government concedes, that surveillance of private property using highly sophisticated
surveillance equipment not generally available to the public, such as satellite technology, might
be constitutionally proscribed absent a warrant.”115 As noted above, the sophistication of
surveillance technology available to drones, such as facial recognition or laser radar which can
“see” through walls, may lead some to question the relevance of prior Fourth Amendment
jurisprudence concerning more rudimentary forms of surveillance technology.

The sophistication of drones also has the ability to break down any practical privacy safeguard. In the
pre-computer age, the greatest privacy protections were neither constitutional nor statutory, but
practical. Putting officers everywhere in the community cost too much for local police departments.
This acted as a natural barrier to excessive police presence. Drones are not hindered by similar
limitations. This is similar to the expansion of GPS technology observed by the five concurring
Justices in United States v. Jones. There, Justice Sotomayor, writing
for herself, noted that because GPS technology was cheaper and This access to inexpensive
performed in a surreptitious manner, it “evades the ordinary checks technology may significantly
that constrain abusive law enforcement practices: limited police reduce budgetary concerns that
once checked the government
resources and community hostility.”116 Justice Alito sounded a similar from widespread surveillance.
note in Jones: “Traditional surveillance for any extended period of
time was difficult and costly and therefore rarely undertaken. [GPS
devices] make long-term monitoring relatively easy and cheap.”117 Instead of putting more officers in
the field, a police force could put drones in the sky for potentially less expense. Already, drones with
video capabilities can be purchased from private vendors for a few hundred dollars.118 This access to
inexpensive technology may significantly reduce budgetary concerns that once checked the
government from widespread surveillance.

The duration and pervasiveness of drone surveillance—two factors closely associated with the
technology employed by law enforcement—may also influence a court’s Fourth Amendment
analysis. Consider the Fifth Circuit Court of Appeals’ ruling in United States v. Cuevas-
Sanchez.119 In that case, federal law enforcement agents suspected the defendant was using his
home as a drop house for drug traffickers. After obtaining a court order, the agents installed a

114
Id. Lockheed has reportedly been working on extending flight times from days to months. Id.
115
Dow Chemical, 476 U.S. at 238.
116
United States v. Jones, 132 S. Ct. 945, 956 (Sotomayor, J., concurring) (internal quotation marks omitted).
117
Id.
118
See, e.g., Apple Store, Parrot AR.Drone 2.0, http://store.apple.com/us/product/H8859ZM/A/parrot-ar-drone-2-0.
This aircraft, is remote-controlled by an iPhone or iPad, and has a high-definition camera that can take both pictures
and videos. Id.
119
United States v. Cuevas-Sanchez, 821 F.2d 248 (5th Cir. 1987).



video camera on a utility pole overlooking the defendant’s 10-foot high fence surrounding his
back yard. The officers observed the removal of drugs from the gas tanks of several cars parked
in the defendant’s yard. Based on these observations, the defendant was arrested whereupon the
police seized a large amount of marijuana. At trial, the defendant moved to suppress the evidence
on the basis that the warrant was defective. However, the court first addressed whether the video
surveillance was a search under the Fourth Amendment. In determining that the video
surveillance was a search, the panel noted that this “was not a one-time overhead flight or a
glance over the fence by a passer-by.... It does not follow that Ciraolo authorizes any type of
surveillance whatever just because one type of minimally-intrusive aerial observation is
possible.”120 Drones have the capability to stay in the air for long periods of time and can hover in
one location. Similar to the mounted camera in Cuevas-Sanchez, this permits law enforcement to
employ drones in prolonged surveillance operations. This capability may sway a court’s
determination of whether certain types of warrantless drone surveillance are compatible with the
Fourth Amendment.

Warrant Requirement and Suspicionless Drone Searches
Applying the Fourth Amendment to drones requires application of the threshold question: was
there a search? Again, this will depend on all the factors discussed above—the area of the search,
the technology used, and whether society would respect the target’s expectation of privacy in the
place searched. If a reviewing court concludes that the drone surveillance was not a search,
neither a warrant nor any degree of individualized suspicion would be required. If, however, the
court concluded there was a search, then a court would ask whether a warrant is required, if one
of the exceptions apply, and what level of suspicion, if any, is necessary to uphold the search.

Unless a meaningful distinction can be made between drone surveillance and more traditional
forms of government tracking, existing jurisprudence suggests that a reviewing court would likely
uphold drone surveillance conducted with no individualized suspicion when conducted for
purposes other than strict law enforcement. The Supreme Court has hesitated from interfering in
what they see as the executive’s function in protecting the health and safety of the American
population. As Chief Justice Rehnquist noted in the Sitz, the Court does not want

to transfer from politically accountable officials to the courts the decision as to which among
reasonable alternative law enforcement techniques should be employed to deal with serious
public danger.... [F]or purposes of Fourth Amendment analysis, the choice among such
reasonable alternatives remains with the governmental officials who have a unique
understanding of, and a responsibility for, limited public resources, including a finite number
of police officers.121

The Court may defer to law enforcement officials in the drone context also. There are countless
instances where the government may seek to utilize drones for health and safety purposes that go
beyond mere law enforcement. These may include firefighting, search and rescue missions, traffic
safety enforcement, or environmental protection. If, on other hand, surveillance is conducted
primarily to enforce the law, a warrant may be required, unless one of the exceptions to the
warrant requirement applies.

120
Id. at 251.
121
Mich. Dep’t of State Police v. Sitz, 496 U.S. 444, 453-54 (1990).



Legislative Proposals in the 113th Congress to
Constrain Domestic Use of Drones
Although the Supreme Court is the final arbiter of the Constitution, Congress and the President
can provide for greater regulation of drones than the Fourth Amendment requires. Congress has
taken such steps over the years to address government surveillance of communications in transit
(commonly known as wiretapping),122 communications in storage such as e-mails,123 bank
records,124 and health records,125 among a host of other private information. Several measures
have been introduced in the 113th Congress that would restrict the domestic use of drones, and
establish arguably greater constraints on their usage than the Fourth Amendment requires. Several
bills were prompted by a general concern for potential privacy intrusions by federal and state law
enforcement and executive agencies.126

Preserving Freedom from Unwarranted Surveillance Act of 2013
(H.R. 972)
In the 113th Congress, Representative Austin Scott has introduced the Preserving Freedom from
Unwarranted Surveillance Act of 2013 (H.R. 972).127 This bill would require any entity acting
under the authority of the federal government to obtain a warrant based upon probable cause
before conducting drone surveillance to investigate violations of criminal law or regulations.
There are, however, several exceptions to this warrant requirement: (1) to prevent or deter illegal
entry of any persons or illegal substances into the United States; (2) when a law enforcement
officer possesses reasonable suspicion that under particular circumstances “swift action to prevent
imminent danger to life or serious damage to property, or to forestall the imminent escape of a
suspect, or destruction of evidence” is necessary; or (3) when the Secretary of Homeland Security
determines credible intelligence indicates a high risk of a terrorist attack by a specific individual
or organization. H.R. 972 would create a right to sue for any violation of its prohibitions.

Preserving American Privacy Act of 2013 (H.R. 637)
Representative Ted Poe introduced the Preserving American Privacy Act of 2013 (H.R. 637),
which would restrict the domestic use of drones.128 To begin, the bill regulates surveillance of
“covered information,” which means “information that is reasonably likely to enable

122
Omnibus Crime Control and Safe Streets Act of 1968, P.L. 90-351, 87 Stat. 197, 211 (codified at 18 U.S.C. §2510-
2522).
123
Electronic Communications Privacy Act of 1986, P.L. 99-508, 100 Stat. 1848 (codified at 18 U.S.C. §2701-2712).
124
Right to Financial Privacy Act, P.L. 95-630, 92 Stat. 3697 (codified at 12 U.S.C. §3401-3422).
125
Health Insurance Portability and Accountability Act of 1996, P.L. 104-191, 110 Stat. 1936.
126
Several bills introduced in the 113th Congress aim to restrict the government’s use of drones to lethally target U.S.
citizens on U.S. soil. See, e.g., No Armed Drones Act of 2013, H.R. 1083, 113th Cong (1st Sess. 2013); S. 505, 113th
Cong. (1st Sess. 2013). These bills, however, are beyond the scope of this report.
127
H.R. 972, 113th Cong. (1st Sess. 2013). Senator Rand Paul filed similar legislation in the 112th Congress, but has not
re-introduced it in the 113th Congress. See S. 3287, 112th Cong. (2d Sess. 2012). Unlike H.R. 972, S. 3287 included an
express exclusionary rule for evidence obtained in violation of the act.
128
H.R. 637, 113th Cong. (1st Sess. 2013).



identification of an individual” or “information about an individual’s property that is not in plain
view.” H.R. 637 would create a general prohibition on the use of drones to collect covered
information or disclose covered information so collected. It does, however, provide the following
exceptions:

• Warrant. Law enforcement obtains a court-issued warrant and serves a copy of
the warrant on the target of the search within 10 days of the surveillance.
However, notice need not be provided if it would jeopardize an ongoing criminal
or national security investigation.
• General Order. Law enforcement obtains a court-issued order based upon
“specific and articulable facts showing a reasonable suspicion of criminal activity
and a reasonable probability” that the operation “will provide evidence of such
criminal activity.” The order may authorize surveillance in a stipulated public
area for no more than 48 hours which may be renewed for a total of 30 days.
Notice of the operation must be provided to the target no later than 10 days after
the operation. Alternatively, notice may be provided not less than 48 hours before
the operation in a major publication, on a government website, or with signs
posted in the area of the operation.
• Border searches. Operation is within 25 miles of national border.
• Consent. The targeted individual has provided prior written consent.
• Emergencies. Emergency situation involves danger of death or serious physical
injury, conspiratorial activities threatening the national security interest, or
conspiratorial activities characteristic of organized crime, where a warrant cannot
be obtained with due diligence. Law enforcement must then obtain a warrant
within 48 hours of such operation.
Any evidence obtained in violation of this act is not admissible in any trial or adjudicative
proceeding. Additionally, H.R. 637 requires any governmental entity applying for a certificate or
license to operate a UAS to also file a data collection statement with the Attorney General. The
statement must include the following:

• Purpose for which the UAS will be used
• Whether the UAS is capable of collecting covered information
• The length of time the information will be retained
• A point of contact for citizen feedback
• The particular unit of governmental entity responsible for safe and appropriate
operation of the UAS
• The rank and title of the individual who may authorize the operation of the UAS
• The applicable data minimization policies barring the collection of covered
information unrelated to the investigation of crime and requiring the destruction
of covered information that is no longer relevant to the investigation of a crime
• Applicable audit and oversight procedures.
Under H.R. 637, the Attorney General may request that the Secretary of Transportation revoke the
license or certificate of any entity that fails to file a data collection statement. Further, H.R. 637



contains a provision permitting administrative discipline against an officer who intentionally
violates a provision of this act.

Drone Aircraft Privacy and Transparency Act of 2013 (H.R. 1262)
Representative Ed Markey introduced the Drone Aircraft Privacy and Transparency Act of 2013
(H.R. 1262).129 This bill would amend the FAA Modernization and Reform Act of 2012 to create
a comprehensive scheme to regulate government actors’ use of drones, including data collection
requirements and enforcement mechanisms.

First, this bill would require the Secretary of Transportation, with input from the Secretary of
Commerce, the Chairman of the Federal Trade Commission, and the Chief Privacy Officer of the
Department of Homeland Security, to study any potential threats to privacy protections posed by
the introduction of drones in the national airspace. Next, the bill would prohibit the FAA from
issuing a license to operate a drone unless the application for such use included a “data collection
statement.” This statement would require the following items:

• A list of individuals who would have the authority to operate the drone
• The location in which the drone will be used
• The maximum period it will be used
• Whether the drone would be collecting information about individuals
If the drone will be used to collect personal information, the statement must include the
following:

• The circumstances in which such information will be used
• The kinds of information collected and the conclusions drawn from it
• The type of data minimization procedures to be employed
• Whether the information will be sold, and if so, under what circumstances
• How long the information would be stored
• Procedures for destroying irrelevant data.
The statement must also include information about the possible impact on privacy protections
posed by the operation under that license and steps to be taken to mitigate this impact.
Additionally, the statement must include the contact information of the drone operator; a process
for determining what information has been collected about an individual; and a process for
challenging the accuracy of such data. Finally, the FAA would be required to post the data
collection statement on the Internet.

In addition to the data collection statement, any law enforcement agency which operates a drone
must file with the FAA a “data minimization statement.” This statement must include policies
adopted by the agency that

129
H.R. 1262, 113th Cong. (2d Sess. 2013).



• minimize the collection of information and data unrelated to the investigation of
a crime under a warrant,
• require the destruction of data that is no longer relevant to the investigation of a
crime,
• establish procedures for the method of such destruction, and
• establish oversight and audit procedures to ensure the agency operates a UAS in
accordance with the data collection statement filed with the FAA.
H.R. 1262 includes several enforcement mechanisms. First, the FAA may revoke a license of a
user that does not comply with these requirements. The Federal Trade Commission would have
the primary authority to enforce the data collection requirements just stated. Additionally, the
Attorney General of each state, or an official or agency of a state, is empowered to file a civil suit
if there is reason to believe that the privacy interests of residents of that state have been
threatened or adversely affected. H.R. 1262 would also create a private right of action for a
person injured by a violation of this legislation.

Conclusion
The introduction of drones into American airspace raises many legal and policy questions. For
instance, how far can the government go in its attempts to maintain security and ensure that laws
are enforced? What level of privacy should Americans expect in an age where technology
facilitating the acquisition of personal information expands at a phenomenal pace? Currently,
there is a vast body of Fourth Amendment law that governs the circumstances in which law
enforcement must obtain a warrant before conducting surveillance. However, the sheer
sophistication of drone technology and the sensors they can carry may remove drones from this
traditional Fourth Amendment framework. Beyond the courts and the Constitution, what role
should Congress and the President play in regulating the introduction of drones inside the United
States? As the integration of drones for domestic surveillance operations quickly accelerates,
these questions and others will be posed to the American people and their political leaders.

Author Contact Information

Richard M. Thompson II
Legislative Attorney
rthompson@crs.loc.gov, 7-8449


CRS R42701 Drones in Domestic Surveillance Operations Fourth Amendment Implications and Legislative Responses

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CRS R42701 Drones in Domestic Surveillance Operations Fourth Amendment Implications and Legislative Responses