Primary Source: Carpenter v. United States (2018)

In Carpenter v. United States, the Supreme Court once again addressed whether the Fourth Amendment’s prohibition on unreasonable searches and seizures applied to modern technology—in this case, to cell phones and smartphones. Can the government subpoena third-party telecommunications providers to provide your physical location, transmitted on an almost ongoing basis to the company cell sites? Is the Fourth Amendment well suited to the Internet Age, where most of our possessions and documents can be found in “the cloud” and in the possession of third-party technology companies?

As technology has enhanced the Government’s capacity to encroach upon areas normally guarded from inquisitive eyes, this Court has sought to “assure [ ] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted.” For that reason, we [previously] rejected . . . a “mechanical interpretation” of the Fourth Amendment . . . .

The question we confront today is how to apply the Fourth Amendment to a new phenomenon: the ability to chronicle a person’s past movements through the record of his cell phone signals. . . . [C]ell phone location information is detailed, encyclopedic, and effortlessly compiled. . . . [I]n 1979 [when a prior case was decided], few could have imagined a society in which a phone goes wherever its owner goes, conveying to the wireless carrier not just dialed digits, but a detailed and comprehensive record of the person’s movements. . . .

Given the unique nature of cell phone location records, the fact that the information is held by a third party does not by itself overcome the user’s claim to Fourth Amendment protection. Whether the Government employs its own surveillance technology . . . or leverages the technology of a wireless carrier, we hold that an individual maintains a legitimate expectation of privacy in the record of his physical movements as captured through [cell phone site data]. The location information obtained from Carpenter’s wireless carriers was the product of a search. . . .

[T]he time-stamped [location] data provides an intimate window into a person’s life, revealing not only his particular movements, but through them his “familial, political, professional, religious, and sexual associations.” These location records “hold for many Americans the ‘privacies of life.’” . . . A cell phone faithfully follows its owner beyond public thoroughfares and into private residences, doctor’s offices, political headquarters, and other potentially revealing locales. Accordingly, when the Government tracks the location of a cell phone it achieves near perfect surveillance, as if it had attached an ankle monitor to the phone’s user. . . .

The Government’s acquisition of the cell-site records was a search within the meaning of the Fourth Amendment. . . . [T]he Government must generally obtain a warrant supported by probable cause before acquiring such records. . . .

The Court has twice held that individuals have no Fourth Amendment interests in business records which are possessed, owned, and controlled by a third party. This is true even when the records contain personal and sensitive information. So when the Government uses a subpoena to obtain, for example, bank records, telephone records, and credit card statements from the businesses that create and keep these records, the Government does not engage in a search of the business’s customers within the meaning of the Fourth Amendment.

In this case petitioner challenges the Government’s right to use compulsory process to obtain a now-common kind of business record: cell-site records held by cell phone service providers. The Government acquired the records through an investigative process enacted by Congress. Upon approval by a neutral magistrate, and based on the Government’s duty to show reasonable necessity, it authorizes the disclosure of records and information that are under the control and ownership of the cell phone service provider, not its customer. . . .

In concluding that the Government engaged in a search, the Court unhinges Fourth Amendment doctrine from the property-based concepts that have long grounded the analytic framework that pertains in these cases. In doing so it draws an unprincipled and unworkable line between cell-site records on the one hand and financial and telephonic records on the other. According to today’s majority opinion, the Government can acquire a record of every credit card purchase and phone call a person makes over months or years without upsetting a legitimate expectation of privacy. But, in the Court’s view, the Government crosses a constitutional line when it obtains a court’s approval to issue a subpoena for more than six days of cell-site records in order to determine whether a person was within several hundred city blocks of a crime scene. That distinction is illogical and will frustrate principled application of the Fourth Amendment in many routine yet vital law enforcement operations. . . .

This case should not turn on “whether” a search occurred. It should turn, instead, on whose property was searched. The Fourth Amendment guarantees individuals the right to be secure from unreasonable searches of “their persons, houses, papers, and effects.” . . . By obtaining the cell-site records of MetroPCS and Sprint, the Government did not search Carpenter’s property. He did not create the records, he does not maintain them, he cannot control them, and he cannot destroy them. Neither the terms of his contracts nor any provision of law makes the records his. The records belong to MetroPCS and Sprint. . . .

The . . . fundamental problem with the Court’s opinion . . . is its use of the “reasonable expectation of privacy” test, which was first articulated by Justice Harlan in Katz v. United States . . . . The Katz test has no basis in the text or history of the Fourth Amendment. And, it invites courts to make judgments about policy, not law. Until we confront the problems with this test, Katz will continue to distort Fourth Amendment jurisprudence. . . .

Of course, the founding generation understood that, by securing their property, the Fourth Amendment would often protect their privacy as well. But the Fourth Amendment’s attendant protection of privacy does not justify Katz’s elevation of privacy as the sine qua non of the Amendment. . . . In shifting the focus of the Fourth Amendment from property to privacy, the Katz test . . . reads the words “persons, houses, papers, and effects” out of the text. . . .