Carpenter v. United States, 585 U.S. ___, 138 S. Ct. 2206 (Jun. 22, 2018)

The Government conducts a search under the Fourth Amendment when it accesses historical cell phone records that provide a comprehensive chronicle of the user’s past movements. Police officers arrested four men suspected of robbing Radio Shack and TMobile stores in Detroit. One of the men confessed to a series of robberies in Michigan and Ohio, identified 15 accomplices, and gave law enforcement some of their cell phone numbers. Based on this information, prosecutors applied for court orders under the Stored Communications Act (SCA) to obtain cell phone records for defendant Timothy Carpenter. The SCA permits the Government to compel the disclosure of certain telecommunications records when it “offers specific and articulable facts showing that there are reasonable grounds to believe” that the records sought “are relevant and material to an ongoing criminal investigation.” Federal Magistrate Judges issued two orders directing Carpenter’s wireless carriers—MetroPCS and Sprint—to disclose “cell/site sector [information] for [Carpenter’s] telephone[ ] at call origination and at call termination for incoming and outgoing calls” during the four-month period when the string of robberies occurred. The first order sought 152 days of cell-site records from MetroPCS, which produced records spanning 127 days. The second order requested seven days of CSLI from Sprint, which produced two days of records covering the period when Carpenter’s phone was “roaming” in northeastern Ohio. Altogether the Government obtained 12,898 location points cataloging Carpenter’s movements—an average of 101 data points per day.

Carpenter was charged with six counts of robbery and six counts of carrying a firearm during a federal crime of violence. He moved to suppress the cell-site data provided by the wireless carriers, arguing that the Government’s seizure of the records violated the Fourth Amendment because they had been obtained without a warrant supported by probable cause. The District Court denied the motion. At trial FBI agent Christopher Hess offered expert testimony about the cell-site data. Hess explained that each time a cell phone taps into the wireless network, the carrier logs a time-stamped record of the cell site and particular sector that were used. With this information, Hess produced maps that placed Carpenter’s phone near four of the charged robberies. Carpenter was convicted on all but one count. After an unsuccessful appeal to the Sixth Circuit, the Supreme Court agreed to take the case.

The Court began by noting that for many years Fourth Amendment search doctrine was “tied to common-law trespass” and focused on whether the Government “obtains information by physically intruding on a constitutionally protected area.” But, in Katz v. United States, 389 U.S. 347, 351 (1967), the Court established that “the Fourth Amendment protects people, not places,” and expanded its conception of the Amendment to protect certain expectations of privacy as well. It explained: “When an individual seeks to preserve something as private, and his expectation of privacy is one that society is prepared to recognize as reasonable, we have held that official intrusion into that private sphere generally qualifies as a search and requires a warrant supported by probable cause.” (quotations omitted).

The Court noted that the digital data at issue in this case does not fit neatly under existing precedents. Instead, requests for cell-site records lie at the intersection of two lines of cases. The first set of cases addresses a person’s expectation of privacy in his physical location and movements, including United States v. Knotts, 460 U. S. 276 (1983) (monitoring a beeper signal in a container in an automobile on public highways did not violate the Fourth Amendment), and United States v. Jones, 565 U.S. 400 (2012)(the government’s installation of a GPS tracking device on a vehicle and its use of that device to monitor the vehicle’s movements on public streets constitutes a search within the meaning of the Fourth Amendment). In the second set of cases, including Smith v. Maryland, 442 U.S. 735 (1979),and United States v. Miller, 425 U.S. 435 (1976), the Court applied the “third-party doctrine” and has drawn a line between what a person keeps to himself and what he shares with others, holding that “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties.” Against this review, the Court presented the issue as follows:

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. Such tracking partakes of many of the qualities of the GPS monitoring we considered in Jones. Much like GPS tracking of a vehicle, cell phone location information is detailed, encyclopedic, and effortlessly compiled.

At the same time, the fact that the individual continuously reveals his location to his wireless carrier implicates the third-party principle of Smith and Miller. But while the third-party doctrine applies to telephone numbers and bank records, it is not clear whether its logic extends to the qualitatively different category of cell-site records. After all, when Smith was decided in 1979, 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

It held:

We decline to extend Smith and Miller to cover these novel circumstances. 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 as in Jones 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 CSLI. The location information obtained from Carpenter’s wireless carriers was the product of a search.

The Court characterized its decision as “a narrow one,” noting:

We do not express a view on matters not before us: real-time CSLI or “tower dumps” (a download of information on all the devices that connected to a particular cell site during a particular interval). We do not disturb the application of Smith and Miller or call into question conventional surveillance techniques and tools, such as security cameras. Nor do we address other business records that might incidentally reveal location information. Further, our opinion does not consider other collection techniques involving foreign affairs or national security.

Having found that the acquisition of Carpenter’s CSLI was a search, the Court went on to conclude that the Government must generally obtain a warrant supported by probable cause before acquiring such records. It noted that the showing required in the SCA “falls well short of the probable cause required for a warrant.” Thus, an order issued under the SCA “is not a permissible mechanism for accessing historical cell-site records. Before compelling a wireless carrier to turn over a subscriber’s CSLI, the Government’s obligation is a familiar one—get a warrant.” The Court continued, noting that while the Government will generally need a warrant to access CSLI, case-specific exceptions may support a warrantless search of an individual’s cellsite records, such as exigent circumstances.