United States v. Chatrie

107 F.4th 319

UNITED STATES of America, Plaintiff - Appellee, v. Okello T. CHATRIE, Defendant - Appellant.The Reporters Committee for Freedom of the Press;American Civil Liberties Union; American Civil Liberties Union of Virginia;Eight Federal Public Defender Offices Within the Fourth Circuit;Technology Law and Policy Clinic at New York University School of Law;Electronic Frontier Foundation, Amici Supporting Appellant.

No. 22-4489

United States Court of Appeals, Fourth Circuit

Argued: December 8, 2023

Decided: July 9, 2024

Appeal from the United States District Court for the Eastern District of Virginia, at Richmond. M. Hannah Lauck, District Judge. (3:19-cr-00130-MHL-1)

ARGUED: Michael William Price, NATIONAL ASSOCIATION OF CRIMINAL DEFENSE LAWYERS, Washington, D.C., for Appellant. Nathan Paul Judish, UNITED STATES DEPARTMENT OF JUSTICE, Washington, D.C., for Appellee. ON BRIEF: Geremy C. Kamens, Federal Public Defender, Alexandria, Virginia, Laura J. Koenig, Assistant Federal Public Defender, OFFICE OF THE FEDERAL PUBLIC DEFENDER, Richmond, Virginia, for Appellant. Kenneth A. Polite, Jr., Assistant Attorney General, Richard W. Downing, Deputy Assistant Attorney General, Computer Crime and Intellectual Property Section, UNITED STATES DEPARTMENT OF JUSTICE, Washington, D.C.; Jessica D. Aber, United States Attorney, Kenneth R. Simon, Jr., Assistant United States Attorney, Peter S. Duffey, Assistant United States Attorney, OFFICE OF THE UNITED STATES ATTORNEY, Richmond, Virginia, for Appellee. Jennifer Lynch, Andrew Crocker, Hannah Zhao, ELECTRONIC FRONTIER FOUNDATION, San Francisco, California; Jacob M. Karr, Technology Law and Policy Clinic, NEW YORK UNIVERSITY SCHOOL OF LAW, New York, New York, for Amici Technology Law and Policy Clinic at New York University School of Law and Electronic Frontier Foundation. Jennifer Stisa Granick, San Francisco, California, Nathan Freed Wessler, Ashley Gorski, Patrick Toomey, Brandon Buskey, Trisha Trigilio, Laura Moraff, AMERICAN CIVIL LIBERTIES UNION FOUNDATION, New York, New York; Eden B. Heilman, Matthew W. Callahan, AMERICAN CIVIL LIBERTIES UNION FOUNDATION OF VIRGINIA, Richmond, Virginia; William F. Nettles, IV, Federal Public Defender, Columbia, South Carolina, G. Alan DuBois, Federal Public Defender, Raleigh, North Carolina, Louis Allen, Federal Public Defender, Greensboro, North Carolina, Juval O. Scott, Federal Public Defender, Roanoke, Virginia, Brian J. Kornbrath, Federal Public Defender, Clarksburg, West Virginia, James Wyda, Federal Public Defender, Baltimore, Maryland, Wesley P. Page, Federal Public Defender, OFFICE OF THE FEDERAL PUBLIC DEFENDER, Charleston, West Virginia; John Baker, Federal Public Defender, FEDERAL DEFENDERS OF WESTERN NORTH CAROLINA, INC., Charlotte, North Carolina, for Amici American Civil Liberties Union, American Civil Liberties Union of Virginia, and Eight Federal Public Defender Offices Within the Fourth Circuit. Bruce D. Brown, Katie Townsend, Gabe Rottman, Grayson Clary, Emily Hockett, REPORTERS COMMITTEE FOR FREEDOM OF THE PRESS, Washington, D.C., for Amicus Reporters Committee for Freedom of the Press.

Before WILKINSON, WYNN, and RICHARDSON, Circuit Judges.

Affirmed by published opinion. Judge Richardson wrote the opinion, in which Judge Wilkinson joined. Judge Wynn wrote a dissenting opinion.

RICHARDSON, Circuit Judge:

Okello Chatrie appeals the district court's denial of his motion to suppress location data obtained using a geofence warrant. He argues that the geofence warrant violated the Fourth Amendment because it lacked probable cause and particularity. But we find that the government did not conduct a Fourth Amendment search when it obtained two hours' worth of Chatrie's location information, since he voluntarily exposed this information to Google. We therefore affirm the district court.

I. Background

This case involves government access to a specialized form of location information maintained by Google. Understanding the nature of this information, how it is generated, and how Google obtains it is necessary to our disposition. Accordingly, we begin with a description of the relevant technology.¹

A. Google Location History and Geofence Warrants

Few readers need an introduction to Google, the technology supergiant that offers products and services like Android, Chrome, Google Search, Maps, Drive, and Gmail. This case, however, is about a particular setting for mobile devices that Google calls "Location History."

Location History is an optional account setting that allows Google to track a user's location while he carries his mobile devices. If a user opts in, Google keeps a digital log of his movements and stores this data on its servers. Google describes this setting as "primarily for the user's own use and benefit." J.A. 131. And enabling it does unlock several useful features for a user. For instance, he can view a "virtual journal" of his past travels in the "Timeline" feature of the Google Maps app. J.A. 128. He can also obtain personalized maps and recommendations, find his phone if he loses it, and receive real-time traffic updates. But Google uses and benefits from a user opting in, too—mostly in the form of advertising revenue. Google uses Location History to show businesses whether people who viewed an advertisement visited their stores. It similarly allows businesses to send targeted advertisements to people in their stores' proximity.

Location History is turned off by default, so a user must take several affirmative steps before Google begins tracking and storing his Location History data. First, he must enable location sharing on his mobile device.² Second, he must opt in to the Location History setting on his Google account, either through an internet browser, a Google application (such as Google Maps), or his device settings (for Android devices). Before he can activate the setting, however, Google always presents him language that explains the basics of the service.³ Third, he must enable the "Location Reporting" feature on his mobile device.⁴ And fourth, he must sign in to his Google account on that device. Only when a user follows these steps will Google begin tracking and storing his Location History data. Roughly one-third of active Google users have enabled Location History.

Even after a user opts in, he maintains some control over his location data. He can review, edit, or delete any information that Google has already obtained. So, for instance, he could decide he only wants to keep data for certain dates and to delete the rest. Or he could decide to delete everything. Google also allows him to pause (i.e., disable) the collection of future Location History data.⁵ Whatever his choice, Google will honor it. From start to finish, then, the user controls how much Google tracks and stores his Location History data.

Once a user enables Location History, Google constantly monitors his location through GPS, even when he isn't using his phone.⁶ And if he has an Android phone, he can turn on another setting—"Google Location Accuracy"—that enables Google to determine his location using more inputs than just GPS, such as Wi-Fi access points and mobile networks. As a result, Location History can be more precise than other location-tracking mechanisms, including cell-site location information. But whether Google Location Accuracy is activated or not, Location History's power should not be exaggerated. In the end, it is only an estimate of a device's location. So when Google records a set of location coordinates, it includes a value (measured in meters) called a "confidence interval," which represents Google's confidence in the accuracy of the estimate.⁷ Google represents that for any given location point, there is a 68% chance that a user is somewhere within the confidence interval.

Google stores all Location History data in a repository called the "Sensorvault." The Sensorvault assigns each device a unique identification number and maintains all Location History data associated with that device. Google then uses this data to build aggregate models to assist applications like Google Maps.

In 2016, Google began receiving "geofence warrants" from law enforcement seeking to access location information. A geofence warrant requires Google to produce Location History data for all users who were within a geographic area (called a geofence) during a particular time period.⁸ Since 2016, geofence requests have skyrocketed in number: Google claims it saw a 1,500% increase in requests from 2017 to 2018 and a 500% increase from 2018 to 2019. Concerned with the potential threat to user privacy, Google consulted internal counsel and law enforcement agencies in 2018 and developed its own three-step procedure for responding to geofence requests. Since then, Google has objected to any geofence request that disregards this procedure.

Google's procedure works as follows: At Step One, law enforcement obtains a warrant that compels Google to disclose an anonymous list of users whose Location History shows they were within the geofence during a specified timeframe. But Google does not keep any lists like this on-hand. So it must first comb through its entire Location History repository to identify users who were present in the geofence. Google then gives law enforcement a list that includes for each user an anonymized device number, the latitude and longitude coordinates and timestamp of each location point, a confidence interval, and the source of the stored Location History (such as GPS or Wi-Fi). Before disclosing this information, Google reviews the request and objects if Google deems it overly broad.

At Step Two, law enforcement reviews the information it receives from Google. If it determines that it needs more, then law enforcement can ask Google to produce additional location coordinates. This time, the original geographical and temporal limits no longer apply; for any user identified at Step One, law enforcement can request...