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Florida v. Riley: Foreshadowing Fourth Amendment Issues in 21st Century Aerial Surveillance and The Need for Clarity

Florida v. Riley: Foreshadowing Fourth Amendment Issues in 21st Century Aerial Surveillance and The Need for Clarity

By: Christopher Beglinger, Volume 103 Staff Member

At its core, the Fourth Amendment reflects the maxim “every man’s house is his castle.”[1] Founded on the Framer’s opposition to abuses of power in searching private homes,[2] the Fourth Amendment affirms the “right of people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.”[3] Although over the past century the Court has aimed to delineate what constitutes a “search and seizure” for purposes of the Fourth Amendment,[4] recent technological advances have forced the Court to confront more complex and sensitive issues situated near the margins.[5] In light of advances in unmanned aerial vehicle (UAV) technologies, uncertainties regarding the impact of Federal Aviation Administration (FAA) regulations, and inconsistencies among state regulations, the Court will likely be forced to reexamine its holding in Florida v. Riley[6] to address the prevailing Fourth Amendment issues relating to law enforcement’s contemporary use of UAVs in aerial surveillance.


Traditionally, the doctrinal framework surrounding the Fourth Amendment’s prohibition against unreasonable searches and seizures was tied to common law trespass.[7] For most of the 20th century, the Court reasoned that “the Fourth Amendment [is] understood to embody a particular concern for government trespass upon the areas (‘persons, houses, papers, and effects’) it enumerates.”[8] However, toward the latter half of the 20th century, the Court deviated from its exclusively property-based inquiry, and expanded the reach of the Fourth Amendment’s protection to people’s reasonable expectations of privacy.[9] The Court reasoned that “the Fourth Amendment protects people, not places,” and stated that “what [people seek] to preserve as private . . . may be constitutionally protected.”[10] Despite the Court’s affirmation that the Fourth Amendment protects against common-law trespass, as well as invasions of certain expectations of privacy,[11] technological advances have forced the Court to analyze trespass and “reasonable” expectations of privacy in ways that strive to balance “conserve[ing] public interests as well as the interests and rights of individual citizens.”[12]


Over the past several decades, progressive implementation of technological advances into law enforcement techniques have challenged the Court to square trespass and privacy doctrines with what constitutes a “search and seizure” for purposes of the Fourth Amendment. For example, in a 5-4 decision in Kyllo, the Court stated that in cases of searches of the interior of homes “there is a ready criterion. . . of [a] minimal expectation of privacy that exists, and that is acknowledged to be reasonable;” thus, “[when] the Government uses a [thermal-imaging] device that is not in the general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a ‘search’. . . .”[13] Moreover, in a plurality opinion in Jones, the Court did not address whether the defendant exhibited a reasonable expectation of privacy regarding a vehicle’s location on public roads, rather the Court held that the attachment of a global positioning system (GPS) to a vehicle was a physical intrusion on an “effect;” thus, constituted a “search” under the Fourth Amendment.[14] As these decisions illustrate, although throughout the 21st century the Court appears to be interpreting the Fourth Amendment under traditional trespass and expectation of privacy doctrines, the divided opinions and differing reasoning’s may indicate that the Court is struggling to circumscribe the appropriate balance of police power in light of technological advances.[15


In addition to concerns surrounding thermal imaging and GPS tracking devices, recent advances have led to Fourth Amendment concerns surrounding the use of UAV, or “drone,” technology in aerial surveillance. Although the Court has yet to decide the scope of the Fourth Amendment’s protection as it relates to UAVs, the Court has developed a body of law surrounding aerial observation that provides a rudimentary framework. For example, in Florida v. Riley the Court held that observations of marijuana plants through openings in a greenhouse, from a helicopter 400 feet above, did not constitute a “search” under the Fourth Amendment.[16]The Court reasoned that because “private and commercial flight by helicopter is routine” and the helicopter was not “violating the law” nor creating undue noise or threat of injury, the respondent could not “reasonably have expected that [his contents] were protected from public or official inspection from the air.”[17] Notably, the dissent in Riley appeared to foreshadow the perplexing issues surrounding UAVs and the Fourth Amendment’s application to aerial surveillance, stating “[i]magine a helicopter capable of hovering just above an enclosed courtyard or patio without generating any noise, wind, or dust. . . . [and suppose] FAA regulations remained unchanged, so that the police were undeniably ‘where they had a right to be’. . . [w]ould [the] plurality continue to assert that [one’s Fourth Amendment rights were] not infringed by such surveillance?”[18] Ironically, what was previously Justice Brennan’s mere theoretical concern in Riley has become a prevailing issue in 21st century police surveillance.


To compound the complexities surrounding Justice Brennan’s concerns in Riley, in 2018 the FAA promulgated rules relating to small unmanned aircraft systems, which impose general operating, registration, and pilot and UAV certification requirements.[19] Although it is clear that FAA regulations regarding aircrafts operating in “navigable airspaces” preempt state and local laws,[20] there remains some uncertainty regarding their impact on state laws that indirectly implicate UAVs.[21] Moreover, although several states have enacted regulations prohibiting certain invasions of airspace,[22] most of which are couched in trespass, constructive invasions of privacy,[23] or invasions of reasonable expectations of privacy[24] doctrines, a majority of states do not have regulations that contemplate the use of UAVs in law enforcement techniques.[25] As a result, society has been brought to a juncture in which UAVs, capable of hovering just above a person’s home, which comply with FAA and (absent) state regulations, may theoretically be used in aerial surveillance without violating the Fourth Amendment.

In light of the Fourth Amendment’s aim to maintain “every man’s house [as] his castle,” and the Court’s emphasis on balancing “the degree to which [surveillance] intrudes upon an individual’s privacy. . . and the degree to which it is needed for the promotion of legitimate governmental interests,”[26] the Court should approve of a holding that restricts the use of UAVs in situations that intrude on personal privacy and security. Under the Kyllo framework, although UAVs have become common in the 21st century, and are arguably devices “in the general public use,” recent FAA regulations impose significant restrictions on UAVs; thus, limiting their availability and use in the general public. Moreover, unlike traditional surveillance techniques, which fit squarely within the Jones framework and common law or state trespass doctrines, the use of UAVs in aerial surveillance has resulted in a doctrinal conundrum. According to Riley, if the use of an aerial surveillance vehicle does not “violat[e] the law,” its use does not constitute a “search” under the Fourth Amendment. Given recent FAA regulations, UAVs can be flown at low altitudes without violating federal laws; however, seeing that (a minority of) states have enacted laws prohibiting invasions of airspace that are couched in “constructive invasions of privacy” or “invasions of reasonable expectations of privacy,” there remains some uncertainty as to what degree of aerial intrusion constitutes a “violation” of trespass laws. As a result, in order to bring clarity to this area of the law, and realign the appropriate balance of police power, the Court should adopt a holding that finds that low altitude aerial surveillance of a person’s home using UAV technology violates a person’s reasonable expectation of privacy under Katz; thus, constitutes a “search” for purposes of the Fourth Amendment. In light of Justice Brennan’s concerns surrounding “remov[ing] virtually all constitutional barriers for police surveillance from the vantage point of [aerial surveillance vehicles],”[27] the proposed holding would not only uphold the Framer’s strong opposition to abuses of power as it relates to aerial surveillance, but also parallel the Court’s more recent privacy-focused holdings regarding technological advances of the 21st century.[28]

  1. Weeks v. United States, 232 U.S. 383, 390 (1914). 
  2. See Boyd v. United States, 116 U.S. 616, 641 (1886). 
  3. U.S. Const. amend. IV. 
  4. Over the past century, the Fourth Amendment’s search and seizure focus has transitioned from common law trespass, to protecting expectations of privacy, to protecting against both trespass and invasions of privacy. See Olmstead v. United States, 277 U.S. 438, 466 (1928) (stating no case has held “the Fourth Amendment [has] been violated. . . unless there [was]. . . actual physical invasion of [the] house”); Katz v. United States, 389 U.S. 347, 361 (1967) (Harlan, J., concurring) (stating that the Fourth Amendment affords protection where a person exhibits an expectation of privacy, which society is prepared to recognize as reasonable); United States v. Jones, 565 U.S. 400, 409 (2012) (stating the “Katz reasonable-expectation-of-privacy test has been added to, not substituted for, the common-law trespassory test”). 
  5. See generally Kyllo v. United States, 533 U.S. 27 (2001) (deciding whether the use of thermal imaging constitutes a “search”); Florida v. Jardines, 569 U.S. 1 (2013) (deciding whether the use of a drug sniffing dog at someone’s porch constitutes a “search”). 
  6. See Florida v. Riley, 488 U.S. 455 (1989) (holding an officer’s observation of the interior of a greenhouse from a helicopter did not constitute a “search”). 
  7. Jones, 565 U.S. at 405. 
  8. Id. at 406. 
  9. See Katz, 389 U.S. at 361 (Harlan, J., concurring) (stating that Fourth Amendment affords protection when a person exhibits “an actual (subjective) expectation of privacy,” which is “one that society is prepared to recognize as ‘reasonable.’”). 
  10. Id. at 351. 
  11. Jones, 565 U.S. at 400. 
  12. Kyllo v. United States, 533 U.S. 27, 40 (2001). See also Orin S. Kerr, An Equilibrium-Adjustment Theory of the Fourth Amendment, 125 Harv. L. Rev. 476, 482 (2011) (describing the equilibrium adjustment theory as a way for courts to stabilize the balance of police power by adjusting rules to tighten or loosen power in response to changing technological issues). 
  13. Kyllo, 533 U.S. at 34, 40. But see Kyllo, 533 U.S. at 47 (Stevens, J., dissenting) (stating a constitutional impediment should not be erected unless it provides police with the equivalent of an actual presence in the area being searched). 
  14. Jones, 565 U.S. at 404. But see Jones, 565 U.S. at 430–31 (Alito, J., concurring) (arguing a search occurred because the lengthy monitoring involved a degree of intrusion that a reasonable person would not have anticipated). 
  15. See Carpenter v. United States, 138 S. Ct. 2206, 2246 (2018) (Thomas, J., dissenting) (stating “a normative understanding is the only way to make sense of the Court’s precedents,” and that the “only thing the past three decades have established. . . is that society’s expectations of privacy bear an uncanny resemblance of those . . . [the] Court considers reasonable.”). 
  16. Florida v. Riley, 488 U.S. 445 (1989). 
  17. Id. at 445, 452. 
  18. Id. at 462–63 (Brennan, J., dissenting). 
  19. Small Unmanned Aircraft Systems, 14 C.F.R. pt. 107 (2018). 
  20. See State and Local Regulations of Unmanned Aircraft Systems (UAS) Fact Sheet, FAA (Dec. 17, 2015) (noting consultation with the FAA is recommended before enacting restrictions on flight altitude, paths, and operational bands). 
  21. See id. (outlining examples of laws relating to state police power that are generally not subject to federal regulation, including privacy, trespass, and law enforcement operations). 
  22. See Andrew Meola, The FAA Rules and Regulations You Need to Know to Keep Your Drone Use Legal, Bus. Insider (July 25, 2017), (outlining states that have enacted drone regulations). 
  23. Cal. Civ. Code § 1708.8(a)–(b). 
  24. Fla. Stat. § 934.50(3)(b). 
  25. See Meloa, supra note 22 (noting thirty states do not have regulations regarding drones). 
  26. Riley v. California, 573 U.S. 373, 385 (2014). 
  27. Id. 
  28. See Carpenter v. United States, 138 S. Ct. 2206 (2018) (holding accessing cell cite records that provide a chronicle of the user’s past movements constitutes a “search”).