Amdt4.2.2.3 Scope of the Rights Protected by the Fourth Amendment: Current Doctrine

Fourth Amendment:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

In United States v. Jones,1 the Court seemed to revitalize the significance of governmental trespass in determining whether a Fourth Amendment search has occurred. In Jones, the Court considered whether the attachment of a Global-Positioning-System (GPS) device to a car used by a suspected narcotics dealer and the monitoring of such device for twenty-eight days, constituted a search. Although the Court ruled unanimously that this month-long monitoring violated Jones’s rights, it splintered on the reasoning. A majority of the Court relied on the theory of common law trespass to find that the attachment of the device to the car represented a physical intrusion into Jones’s constitutionally protected effect or private property.2 While this holding obviated the need to assess the month-long tracking under Katz’s reasonable expectation of privacy test, five Justices, who concurred either with the majority opinion or concurred with the judgment, would have held that long-term GPS tracking can implicate an individual’s expectation of privacy.3 Some have read these concurrences as partly premised on the idea that while government access to a small data set—for example, one trip in a vehicle—might not violate one’s expectation of privacy, aggregating a month’s worth of personal data allows the government to create a mosaic about an individual’s personal life that violates that individual’s reasonable expectation of privacy.4

The Court confirmed in Carpenter v. United States that the Fourth Amendment is implicated when government action violates individuals' reasonable expectation of privacy in the whole of their physical movements, regardless of whether the challenged conduct constitutes a physical trespass.5 The Court held that the government could not, without a warrant, access seven days of a defendant's cell-site location information, which is data that continuously tracks the location of a cell phone.6 Observing that historical cell-site records present even greater privacy concerns than the GPS monitoring of a vehicle we considered in Jones, the Court highlighted the continuing importance of the expectations-of-privacy test.7 The Court acknowledged that it had previously declined to extend Fourth Amendment protection to information that a person had voluntarily given to a third party like a wireless carrier, but declined to extend that line of cases to the qualitatively different category of cell-site records.8


  1.  Jump to essay-1565 U.S. 400 (2012).
  2.  Jump to essay-2Id. at 403–07. The physical trespass analysis was reprised in subsequent opinions. In its 2013 decision in Florida v. Jardines, the Court assessed whether a law enforcement officer had the legal authority to conduct a drug sniff with a trained canine on the front porch of a suspect’s home. Reviewing the law of trespass, the Court observed that visitors to a home, including the police, must have either explicit or implicit authority from the homeowner to enter upon and engage in various activities in the curtilage (i.e., the area immediately surrounding the home). Finding that the use of the dog to find incriminating evidence exceeded background social norms of what a visitor is normally permitted to do on another’s property, the Court held that the drug sniff constituted a search. 569 U.S. 1, 7–10 (2013). Similarly, in its 2015 per curiam opinion in Grady v. North Carolina, the Court emphasized the physical intru[sion] on a person when it found that attaching a device to a person’s body, without consent, for the purpose of tracking the person’s movements, constitutes a search within the meaning of the Fourth Amendment. 135 S. Ct. 1368, 1371 (2015). Neither the majority in Jardines nor the Court in Grady addressed whether the challenged conduct violates a reasonable expectation of privacy under Katz v. United States. Grady, 135 S. Ct. at 1371; Jardines, 569 U.S. at 10–12.
  3.  Jump to essay-3Jones, 565 U.S. at 400, 431 (Alito, J., concurring in the judgment, joined by Ginsburg, Breyer, Kagan, JJ.) (concluding that respondent’s reasonable expectations of privacy were violated by the long-term monitoring of the movements of the respondent’s vehicle); id. at 415 (Sotomayor, J., concurring) (disagreeing with Justice Alito’s approach to the specific case but agreeing longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.).
  4.  Jump to essay-4See, e.g., In re Application for Telephone Information Needed for a Criminal Investigation, 119 F. Supp. 3d 1011, 1021–22 (N.D. Cal. 2015) (discussing the import of the two concurring opinions from Jones); United States v. Brooks, 911 F. Supp. 2d 836, 842 (D. Ariz. 2012) (noting that [w]hile it does appear that in some future case, a five justice ‘majority’ is willing to accept the principle that Government surveillance can implicate an individual’s reasonable expectation of privacy over time, Jones does not dictate the result of the case at hand . . .); but see United States v. Graham, 824 F.3d 421, 435–36 (4th Cir. 2016) (arguing that Justice Alito’s Jones concurrence should be read more narrowly so as to not implicate government access to information collected by third-party actors, no matter the quantity of information collected); In re Application of FBI, No. BR 14–01, 2014 WL 5463097, at *10 (FISA Ct. Mar. 20, 2014) (While the concurring opinions in Jones may signal that some or even most of the Justices are ready to revisit certain settled Fourth Amendment principles, the decision in Jones itself breaks no new ground . . .).
  5.  Jump to essay-5138 S. Ct. 2206, 2217 (2018).
  6.  Jump to essay-6Id. at 2216–17.
  7.  Jump to essay-7Id. at 2218.
  8.  Jump to essay-8Id. at 2216–17.