The highest court in the country and the ultimate interpreter of the Constitution, including the extent to which constitutional law protects privacy. The U.S. Supreme Court's test for deciding when and where a person is constitutionally protected against government intrusion is called reasonable expectation of privacy.
Like most Americans, U.S. Supreme Court justices understand that modern technologies bring both advantages and disadvantages. On the one hand, these new digital tools aid law enforcement efforts and strengthen our nation's security. They also carry information to broad audiences and open up courtrooms far beyond their physical seating capacity. They make it easier and cheaper to connect Americans to each other, the world, and their government. These very advances in technology, however, also threaten to diminish Americans' treasured personal privacy.
The justices are entrusted with the job of balancing these competing interests, and their decisions carry potentially long-term consequences. Indeed, they have been assigned the exceedingly difficult and sometimes contradictory roles of being both the guardians of the past and the predictors of the future. As guardians of the past, the justices are duty-bound to apply, with rare exceptions, existing legal concepts and precedents. Legal analysis depends on uniformity and predictability over time. Thus, the justices must honor the decisions of past courts and established legal rules.
They are also tasked with writing opinions that will be applied now and in the future. In this role, they must analyze increasingly novel uses of modern technology while remaining mindful of how the legal guidelines they announce today might be applied in future cases. The Court summed up these dual tasks in a 1909 decision, declaring: “In the application of a Constitution … our contemplation cannot be only of what has been, but of what may be” (Weems v. United States, 217 U.S. 349, 373 (1910)).
When addressing issues of new and evolving technology, therefore, the Supreme Court is most comfortable when it can analogize a new technology to an older, more familiar, and time-tested scenario. Finding common ground between modern technology and past situations grounds their decisions in legal precedent. Thus, the justices tend to query whether a new technology is the equivalent of trespassing into someone's home or of recording a suspect's fingerprints.
Sometimes the analogy seems like a logical fit. In other cases, however, the relevant comparisons are less clear. When this happens, the Court's opinions can lead to dead ends, conflicting conclusions, or even arguably absurd arguments. Nonetheless, the justices have continued to approach cases involving privacy interests in digital information through the process of applying old law to new technologies.
The Supreme Court and traditional privacy
Issues about privacy in a digital world have reached the Court through several different legal channels. Digital privacy concerns have appeared in cases involving legal issues such as freedom of speech (Bartnicki v. Vopper, 532 U.S. 514 (2001)), rights of press access (Hollingsworth v. Perry, 558 U.S. 183 (2010)), questions of standing (whether a particular party may bring certain cases, Clapper v. Amnesty Int'l USA, 133 S. Ct. 1138 (2013)), freedom of association (John Doe No. 1 v. Reed, 561 U.S. 186 (2010)), federal court jurisdiction (Mims v. Arrow Fin. Servs., LLC, 132 S. Ct. 740 (2012)), child pornography (Paroline v. United States, 134 S. Ct. 1710 (2014)), compelled disclosure of medical records (Nat'l Aeronautics & Space Admin. v. Nelson, 562 U.S. 134 (2011)), and statutory freedom of information claims (National Archives and Records Administration v. Favish, 541 U.S. 157 (2004)). It is, however, the Court's ongoing examination of the Fourth Amendment that protects “the people” from “unreasonable searches and seizures” by the government, that has provided most of the justices' insights into privacy in the digital age. The Court's Fourth Amendment jurisprudence pits the individual's interests in personal privacy against the government's interest in effective law enforcement.
From as early as the mid-nineteenth century, the Court has acknowledged that the Fourth Amendment's declaration that “the right of the people to be secure in their persons, houses, papers, and effects” included not just physical intrusions but also matters of personal privacy—even though the word privacy never appears. In an 1886 decision, for example, the Court held that Fourth Amendment rights “apply to all invasions on the part of the government and its employes [sic] of the sanctity of a man's home and the privacies of life” (Boyd v. United States, 116 U.S. 616, 630 (1886)).
At the center of the Court's traditional Fourth Amendment jurisprudence is the right of privacy within the home. In a 2013 case, Justice Antonin Scalia wrote that “when it comes to the Fourth Amendment, the home is first among equals. At the Amendment's ‘very core’ stands ‘the right of a man to retreat into his own home and there be free from unreasonable government intrusion’” (Florida v. Jardines, 133 S. Ct. 1409, 1414 (2013) [quoting Silverman v. United States, 365 U.S. 505, 511 (1961)]).
The Court concluded that this right extended to the home's curtilage as well. Thus, when the police brought a drug-sniffing dog onto the porch of a private home without a warrant, the Court held that the privacy of the home's residents had been violated. The Court has further extended this protection to other personal spaces in which a person has an expectation of privacy, such as offices, hotel rooms, and telephone booths (Katz v. United States, 389 U.S. 347, 359 (1967)).
While the justices have strongly supported an individual's privacy rights while at home, this support drops quickly once the individual leaves his or her house or interacts with the outside world. The Court has held that there is no Fourth Amendment protection for that which “a person knowingly exposes to the public” (Id. at 351). Thus, once a person exposes any personal information to the public sphere, his or her expectations of privacy diminish or disappear.
The Court has found, for example, that there is no expectation of privacy in the sound of one's voice (United States v. Dionisio, 410 U.S. 1 (1973)) or in the visible characteristics of handwriting (United States v. Mara, 410 U.S. 19, 21–22 (1973)), explaining that “[n]o person can have a reasonable expectation that others will not know the sound of his voice, any more than he can reasonably expect that his face will be a mystery to the world” (Dionisio, 410 U.S. at 14 (1973)).
Over time, the justices extended this concept of “public” space to cover information that can be gleaned with the use of special tools. This means that objects in a person's backyard are not private if they can be seen from an airplane (California v. Ciraolo, 476 U.S. 207 (1986); Florida v. Riley, 488 U.S. 445 (1989)), even if seeing them required a “precision aerial mapping camera”(Dow Chem. Co. v. United States, 476 U.S. 227, 229 (1986)). They likewise decided that a driver has no privacy interests in smells emanating from his car, even if only a trained dog can detect them (Illinois v. Caballes, 543 U.S. 405, 410 (2005)).
The Court and privacy in the digital age
Airplanes and drug-sniffing dogs do not compare, however, to the capabilities of modern technology. With the right to be free of unreasonable searches and seizures traditionally grounded in physical concepts such as trespass and actual barriers, it is not obvious how to treat the intangible intrusions made possible by today's powerful electronic technologies. These technological advances have blurred the once clear physical lines and raised new questions about the limits on government invasion of personal spaces and private matters.
The Court first faced questions about privacy and nonphysical intrusions in early cases on government wiretapping of telephone conversations. Initially, the Court applied the concept of physical trespass to the intercepted telephone conversations and concluded there was no privacy right. In a 1928 case, for example, the Court declared that there was no constitutional violation with government wiretapping because “[t]here was no searching. There was no seizure. The evidence was secured by the use of the sense of hearing and that only. There was no entry of the houses or offices of the defendants” (Olmstead v. United States, 277 U.S. 438, 464 (1928)), The Court also applied its concept that there is no privacy interest once a person has reached out to the outside world, explaining that “one who installs in his house a telephone instrument with connecting wires [and] intends to project his voice to those quite outside” has no Fourth Amendment protection (Id. at 46).
In dissent, Justice Louis Brandeis was less sure if reliance on physical barriers or connections with wires and telephone services was the right approach. He expressed concern that this type of traditional thinking about government intrusion would not suffice in the face of evolving technology. He warned his brethren that “[t]he progress of science in furnishing the government with means of espionage is not likely to stop with wiretapping. Ways may someday be developed by which the government, without removing papers from secret drawers, can reproduce them in court, and by which it will be enabled to expose to a jury the most intimate occurrences of the home” (Id. at 474 (Brandeis, J., dissenting)).
In time, the rest of the Court caught up with Justice Brandeis's views. In the key 1967 case of Katz v. United States, the Court overruled its earlier opinion on wiretapping and concluded that electronically eavesdropping on a confidential conversation did constitute a search even without a physical intrusion (Katz, 389 U.S. 347 (1967)). The Court held that the Fourth Amendment “protects people—and not simply ‘areas’” and “cannot turn upon the presence or absence of a physical intrusion into any given enclosure (Id. at 353). In Katz, the Court established that the crucial inquiry is whether or not the person at that time had a “reasonable expectation of privacy” (Id. at 360–61 (Harlan, John Marshall, II, concurring)).
Building on this idea, the justices have found that privacy rights do exist when enhanced technologies are used to infiltrate the inner spaces of the home or body. Thus, while law enforcement officers may use (without a warrant) an airplane and sophisticated viewing technology to peer into a person's backyard, the Court has said that they may not use thermal radiation imaging to detect unusual amounts of heat coming from someone's home. The difference, according to the Court, is that the latter allows the government “to explore details of the home that would previously have been unknowable without physical intrusion” (Kyllo v. United States, 533 U.S. 27, 40 (2001)).
Digital technologies are unique not just because of their nonphysical nature but also because of the amount and breadth of information they can hold. The Court recognized how these storage capabilities can affect personal privacy recently in the 2014 case of Riley v. California (134 S. Ct. 2473 (2014)). The issue in Riley was whether police could search the contents of a person's cell phone during an arrest without warrant. In earlier cases, the Court had allowed officers to search items found on a person during an arrest, such as a wallet or cigarette package (United States v. Robinson, 414 U.S. 218, 236 (1973)). In Riley, however, the Court unanimously drew a line at cell phones, noting the significant differences in the quantity and quality of information they contained. Chief Justice John Roberts explained that “[p]rior to the digital age, people did not typically carry a cache of sensitive personal information with them as they went about their day. Now it is the person who is not carrying a cellphone, with all that it contains, who is the exception” (Riley v. California, 134 S. Ct. at 2490). Noting that cell phones are actually “minicomputers,” the Court further held that they “collect in one place many distinct types of information—an address, a note, a prescription, a bank statement, a video—that reveal much more in combination than any isolated record” (Id. at 2489).
While broadening its view of personal spaces, however, the Court has continued to embrace the other traditional approach to privacy rights—looking to see whether a person purposely interacts with the public sphere. The Court has applied this concept of willful public disclosure to cases involving electronic information. In a 1979 case, for example, the justices concluded that there is no reasonable expectation of privacy in the telephone numbers dialed on a phone because making the call requires the caller to disclose that information to an outside party—the telephone company (Smith v. Maryland, 442 U.S. 735, 744–45 (1979)).
In concurrence with another case, Justice Sonia Sotomayor questioned whether this rule makes sense in the digital age. She observed that the Court should “reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties” (United States v. Jones, 132 S. Ct. 945, 957 (2012) (Sotomayor, J., concurring)). She went on to observe that, in the modern world, people must “reveal a great deal of information about themselves to third parties in the course of carrying out mundane tasks” (Id.).
In coming years the Court might also reexamine its earlier view that a person has no privacy interest in anything that can be visibly seen in public. Traditionally, for example, the Court held that there is no privacy right in a person's public movements or activities. The police can follow someone's car (Cardwell v. Lewis, 417 U.S. 583, 589–90 (1974); plurality opinion), the justices held, because the driver has “voluntarily conveyed to anyone who wanted to look the fact that he was traveling over particular roads in a particular direction, the fact of whatever stops he made, and the fact of his final destination when he exited from public roads onto private property” (United States v. Knotts, 460 U.S. 276, 281–82 (1983)). By this same logic, the Court upheld police use of a radio transmitter to track the movements of a suspect's car (Id. at 282).
In a 2012 case, the Court was faced with this question again but this time with a new technological tool—a global positioning system (GPS) device. The issue was whether a constitutional violation occurred when the police placed a GPS device on a person's car and used it to monitor the car's movements twenty-four hours a day for almost a month (Jones, 132 S. Ct. at 948). The Court concluded there was a privacy violation. It did so, however, by relying on the concept of a physical trespass, stating that the government physically intruded upon the defendant's property by placing the device on the car without permission (Id. at 949). It did not decide whether the GPS tracking would have been unlawful without the physical trespass.
In a concurring opinion, Justice Samuel Alito observed that technology was changing the public's expectations of privacy and noted that, “[i]n the pre-computer age, the greatest protections of privacy were neither constitutional nor statutory, but practical,” with time and money placing limits on government intrusions; “[d]evices like the one used in the present case, however, make long-term monitoring relatively easy and cheap” (Id. at 963–64 (Alito, J., concurring)).
Finally, the justices divided on the impact of digital technology on the privacy of the human body. The Court has held that government intrusion into a person's body, like government intrusion on the sanctity of the home, involves important privacy rights, noting that “any compelled intrusion into the human body implicates significant, constitutionally protected privacy interests” (Missouri v. McNeely, 133 S. Ct. 1552, 1565 (2013)). Based on this principle, the justices have held that forcibly obtaining a blood sample, a urine sample, or a breath test raises constitutional issues and requires a warrant (Skinner v. Ry. Labor Execs.' Ass'n, 489 U.S. 602, 616–17 (1989); Schmerber v. California, 384 U.S. 757, 769–70 (1966)). They upheld exceptions to this general rule only in “reasonable [and] appropriate circumstances” (McNeely, 133 S. Ct. at 1565).
Modern technical advances have again raised issues of the proper analogy to bodily intrusions. New technological tools can extract far more personal information from the testing of bodily material than before. Pondering these developments, the justices have argued over whether the crucial privacy issue is how the information was obtained or what the information reveals.
The justices agree that when the police take a person's photograph for identification purposes, there is no constitutional concern. They have extended this concept to fingerprinting and handwriting samples. They nevertheless drew the line at scraping material from underneath a person's fingernail, concluding that such action involved “severe, though brief, intrusion” on the body (Cupp v. Murphy, 412 U.S. 291, 295 (1973) (quoting Terry v. Ohio, 392 U.S. 1, 24–25) (1968)).
Recently, however, the justices were faced with the question of whether a police swab of a person's cheek for the purposes of collecting DNA evidence was akin to photographing or fingerprinting an arrestee or whether it was something else entirely. In a 5–4 decision, the Court held that the bodily intrusion of a cheek swab was minimal, and the use of DNA for identification purposes was reasonable (Maryland v. King, 133 S. Ct. 1958, 1980 (2013)).
Four justices disagreed, however, arguing that the information contained in DNA evidence is not used for identification but for the significantly different purpose of trying to solve old cases. This, according to the dissenters, makes it akin to a “general warrant” against all persons (Id. at 1980–81 (Scalia, J., dissenting)). In dissent, Justice Scalia warned that the Court's failure to recognize the inherent privacy interest in DNA could lead to a world where “your DNA can be taken and entered into a national DNA database if you are ever arrested, rightly or wrongly, and for whatever reason” (Id. at 1989).
As technology advances, so must the law. The Supreme Court has struggled to keep pace with the digital world. Often the justices have turned to old case law and analogies to find answers. Increasingly, however, the justices are realizing the limitations of that approach. Until they settle on a new framework on how to balance privacy and information in the digital age, however, they will likely continue to take incremental steps on an as-needed basis.