U.S. Supreme Court
Although the government has developed many ways of using new technologies to gather information about people, the U.S. Supreme Court has only begun to consider how the Fourth Amendment applies to them.
In 2018, in Carpenter v. United States, the court ruled 5-4 that obtaining a large amount of cellular location information about a person is a search for which police must have a warrant. On Monday, the court heard arguments in the latest major case about technology and the Fourth Amendment: Chatrie v. United States, which concerns the police use of a “geofence” to obtain information about all of the cellphones within an area at a particular time.
What happened?
The case arose with the police investigating a bank robbery that occurred at Call Federal Credit Union in Midlothian, Virginia, on May 20, 2019. When the police investigation stalled, the police obtained a geofence warrant from a magistrate judge directed at Google to obtain a list of all of the cellphones within a 300-meter diameter centered on where the robbery occurred between 4:20 p.m. and 5:20 p.m. that day.
Google has a feature called location history, and it is estimated that 500 million people have enabled it. As Chatrie’s brief explains: “Every two minutes on average, location history draws on GPS information, Bluetooth beacons, cell site location information (“CSLI”), IP address information, and nearby Wi-Fi networks to record a device’s location. Location history can determine a person’s location to within three meters and can determine a person’s elevation within a building.” Location history is collected even when the phone is not in use.
The information initially provided by Google to the police in response to the warrant did not include the names of the individuals whose phones were in the area. After obtaining this information, and without an additional warrant, the police asked Google for location history for 19 users for an additional hour of time and outside of the geofence area. It did not include information identifying people by name. Then the government asked Google for the names and account identifiers—including email addresses and phone numbers—associated with three particular devices. This, too, was obtained without an additional warrant. Based on this information, Okello Chatrie was identified.
Chatrie was indicted and prosecuted for the robbery. His lawyer moved to suppress the information gained from the geofence warrant. The district court found that the geofence warrant violated the Fourth Amendment, but held that the exclusionary rule did not apply because it was not an intentional or reckless violation of the Constitution. Chatrie entered a conditional guilty plea and appealed. The Richmond, Virginia-based 4th U.S. Circuit Court of Appeals affirmed, concluding that there was not a search because Chatrie had voluntarily shared his information with Google. Under the third-party doctrine, a person does not have a reasonable expectation of privacy in information that is voluntarily shared with a third person.
The 4th Circuit granted en banc review and affirmed in a one-sentence opinion. The court divided 7-7 on whether a Fourth Amendment search had occurred, with one judge declining to reach the issue. Six of the judges who found a search occurred nonetheless would not have suppressed the evidence on the grounds that the police acted in good faith.
The Supreme Court did not grant certiorari on the question of whether the exclusionary rule applies, instead deciding to hear only this question: “Whether the execution of the geofence warrant violated the Fourth Amendment.”
The issues presented
There are distinct Fourth Amendment issues presented concerning the different steps of the police actions in obtaining the information about Chatrie. One question is whether the geofence warrant violated the Fourth Amendment. Chatrie argued to the Supreme Court that the geofence warrant lacked the specificity required by the Fourth Amendment and was a “general warrant” that the Constitution was meant to forbid. He argued in his brief: “The geofence warrant was an unconstitutional general warrant. The warrant compelled Google to conduct a fishing expedition through millions of Google accounts without any basis for believing that any one of them would contain incriminating evidence.” The brief said that the “Fourth Amendment requires a warrant to identify a particular account, supported by probable cause that incriminating evidence exists in that account.”
Chatrie argued that he had a reasonable expectation of privacy in his location history information. He relied on Carpenter v. United States, which held that the police needed a warrant based on probable cause to obtain 127 days of cellular location information about an individual. The court in Carpenter expressly rejected the argument that Carpenter had no expectation of privacy because he had shared this information with a third party, the cellular company.
The United States argued that there was no expectation of privacy, so the Fourth Amendment did not apply. The Supreme Court has held that we generally do not have an expectation of privacy in our conduct in public. Moreover, the government stresses that Chatrie voluntarily activated the location history feature on his phone and shared the information with Google. The solicitor general’s brief argued: “An individual has no reasonable expectation of privacy in movements that anyone could see, that he has opted to allow a third party to analyze for its own purposes, and that are sufficiently short-term that they reveal little, if anything, about the patterns of his life—particularly when his identity remains anonymous.” The government also emphasizes that such information can be obtained by a warrant, and one was obtained here by the police that met the specificity requirements of the Fourth Amendment.
Even if the police acted properly in securing the geofence warrant, another question before the court is whether they violated the Fourth Amendment in not securing an additional warrant before obtaining from Google the additional information for the larger time and distance and then gaining the names of specific individuals. Chatrie argued that separate warrants were required at each of these stages, while the government contended that the initial warrant authorized the police to obtain the additional information from Google.
Implications
The case raises a host of important issues concerning the application of the Fourth Amendment to new technology. Both Chatrie and the government understandably pay a great deal of attention to the meaning of Carpenter v. United States. Chatrie sees it as requiring a warrant with specificity before the police use technology to obtain information from cellular companies about a person’s location and views Carpenter as greatly limiting the third-party doctrine. The United States argues that Carpenter was much more limited to circumstances where police obtained a very large amount of information without a warrant based on probable cause.
It is important to note that Carpenter was a 5-4 decision with the majority opinion written by Chief Justice John Roberts and joined by Justices Ruth Bader Ginsburg, Stephen Breyer, Sonia Sotomayor and Elena Kagan. Justices Clarence Thomas, Samuel Alito, Anthony Kennedy and Neil Gorsuch each wrote separate strong dissents. It is unclear whether Carpenter would be decided the same way today, especially with Justice Amy Coney Barrett having replaced Justice Ginsburg. Might the court in deciding Chatrie reconsider or narrow Carpenter?
There are a host of new technologies that police use to obtain information about individuals: drones; cameras on utility poles; obtaining a list of all cellphones linked to a cell tower at a particular time; cell-site simulators, which are devices that can list all of the cellphones in an area; and much more. In addition to resolving issues concerning the use of geofences, the court’s decision in Chatrie could provide much-needed guidance as to how the Fourth Amendment should be applied to new technology used by police to gather information about individuals.
Erwin Chemerinsky is dean of the University of California at Berkeley School of Law. He is an expert in constitutional law. He’s also the author of many books, including his most recent ones: Campus Speech and Academic Freedom: A Guide for Difficult Times and The Supreme Court October Term 2024: Taking Sides.
This column reflects the opinions of the author and not necessarily the views of the ABA Journal—or the American Bar Association.
