By Olivia Bayne

            Can privacy exist in the digital age? Most at least hope (if not entirely expect) that our associations and communications are generally private and protected under the First and Fourth Amendments.[1] We figure that so long as we do not actively broadcast the intimate details of our lives to the world at large (e.g., taking obnoxiously loud phone calls in crowded public spaces, making incriminatingly controversial public social media posts, etc.), our dealings will remain our own.

            But in recent years, technology has begun to shift expectations of privacy. Growing numbers of Americans are expressing concerns about how collected personal data is being used, both by private companies and by the government.[2] Many companies have responded with marketing campaigns highlighting end-to-end encryption features or on-device processing updates.[3] But these solutions fail to address the root cause of the public’s unease: bewildering privacy laws.[4] The fast-paced innovations of the private sector often seem to leave judicial processes in the dust. Many of the legal principles at the foundation of privacy law seem inapplicable and woefully dated. Perhaps the most major of these principles—the reasonable expectation of privacy test—is derived from the landmark Supreme Court decision, Katz v. United States.[5]

            At issue in Katz was the warrantless wiretapping of a public telephone booth used for out-of-state gambling.[6] The government argued that because there was no physical penetration of the booth there had been no Constitutional violation, and the conversations overheard through the wiretap were thus admissible as evidence.[7] The Court disagreed.[8] It held that in light of certain technological developments, the Fourth Amendment’s privacy protections could no longer exclusively apply to physical trespasses but must instead be interpreted more broadly.[9] Though the majority is fairly vague as to the qualifying factors of this interpretation, Justice Harlan’s concurrence introduces a two-part test.[10] This test essentially laid the modern foundation for Constitutional privacy protections, requiring that (1) a person exhibits an actual (subjective) expectation of privacy, and (2) that expectation is one that society is prepared to recognize as reasonable.[11]

            While initially this seemed like a fine enough test, its circularity became evident as society’s expectations evolved. In Smith v. Maryland, a little over ten years later, the Court applied the Katz test to determine whether an individual had a reasonable expectation of privacy in the phone numbers they dialed on their landline.[12] The Court determined that no right to privacy existed for two reasons.[13] Firstly, the individual, by dialing the numbers, knowingly conceded the information to the telephone company, i.e., a third party, and thus failed to exhibit an expectation of privacy.[14] Secondly, society would not deem this expectation of privacy reasonable because presumably everyone knows that telephone companies save this information for billing purposes.[15] Justice Marshall dissented, with the cryptic warning that the legitimacy of our privacy expectations should not be nullified by our inevitable use of third-party technology that has become an indispensable part of modern life.[16]

            Fast forward another thirty years or so and the cracks of the Katz test spread further. In United States v. Jones, the Court inquired whether the government’s installation of a tracking device on an individual’s car constituted an unlawful search.[17] The Court found that it did, but rather than applying its usual Katz analysis, the Court reverts to the traditional trespass doctrine, on the basis that this case involved the physical installation of a device on the individual’s property.[18] Yet two prophetic concurrences were frustrated by the missed opportunity to reevaluate Katz in relation to modern surveillance powers.

            The concurrences, written by Justices Sotomayor and Alito, discuss the potential complications of the circularity of the Katz test. Justice Sotomayor points out that the third-party doctrine derived from Katz is “ill-suited to the digital age, in which people reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks.”[19] This “great deal of information” is often disclosed only for a limited purpose and should not lose all Fourth Amendment protections in that process.[20] Justice Alito then draws attention to the fatal flaw of the Katz test: its assumption that society has developed a stable, unchanging set of privacy expectations at all.[21] Justice Alito notes that the Katz test rests on the assumption that a hypothetic reasonable person has a well-developed and stable set of privacy expectations that remain consistent in the face of dramatic technological change. [22] But this is an unrealistic assumption—popular expectations may fluctuate as society seeks increased convenience and security at the expense of privacy; even those that do not find the tradeoff worthwhile may consider the loss of privacy inevitable.[23]

            Both Justice Sotomayor’s and Justice Alito’s concerns are perhaps best illustrated by current public sentiments. There is an overwhelming concern regarding personal data usage and a notable discrepancy between the level of privacy society has come to “expect,” and the level of privacy it would prefer (and presumably deem reasonable). With data collection technology developing at such a rapid pace, it is hard for any person to have a solid idea of which privacies are protected. It may be time for the Court to refine its definition of “reasonable expectations.”

[1] U.S. Const. amends. I, IV.

[2] Michelle Faverio, Key findings about Americans and data privacy, Pew Rsch. Ctr., (Oct. 18, 2023), https://www.pewresearch.org/short-reads/2023/10/18/key-findings-about-americans-and-data-privacy/ (finding that 7 in 10 (up from around 64% in 2019) Americans were concerned about how the government uses their personal information and bipartisan support for more government regulations to protect personal information); Brooke Auxier et al., Americans and Privacy: Concerned, Confused and Feeling Lack of Control Over Their Personal Information, Pew Rsch. Ctr., (Nov. 15, 2019), https://www.pewresearch.org/internet/2019/11/15/americans-and-privacy-concerned-confused-and-feeling-lack-of-control-over-their-personal-information/ (explaining that approximately 79% of Americans are concerned about the way private companies are using their data and 64% are concerned about the way the government is using their data).

[3] Andrew Hutchinson, WhatsApp Underlines Commitment to Privacy in New Ad Campaign, Soc. Media Today, (May 19, 2025), https://www.socialmediatoday.com/news/whatsapp-privacy-focussed-ad-campaign/748552/; Apple extends its privacy leadership with new updates across its platforms, Apple, (June 10, 2024), https://www.apple.com/newsroom/2024/06/apple-extends-its-privacy-leadership-with-new-updates-across-its-platforms/.

[4] See Auxier, supra note 2.

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

[6] Id. at 348–349.

[7] Id. at 350.

[8] Id.

[9] Id. at 352–53.

[10] Id. at 361.

[11] Id.

[12] Smith v. Maryland, 442 U.S. 735, 740 (1979).

[13] Id. at 742–44.

[14] Id. at 742–43.

[15] Id. at 743–45.

[16] Id. at 748–52 (Marshall, J., dissenting).

[17] United States v. Jones, 565 U.S. 400, 402 (2012).

[18] Id. at 404–05 (reasoning that by mounting a GPS tracking device on an individual’s car, the Government had physically occupied private property for the purpose of obtaining information – an action that would undoubtably have been considered a trespassory “search” within “the meaning of the Fourth Amendment when it was adopted.”).

[19] Jones, 565 U.S. at 417 (Sotomayor, J., concurring).

[20] Id. at 418.

[21] Id. at 427 (Alito, J., concurring).

[22] Id.

[23] Id.