Why It Matters

A new Congressional Research Service report examines whether reverse warrants, including geofence warrants and keyword warrants, comply with the Fourth Amendment. Unlike a conventional warrant that begins with a known suspect, a reverse warrant starts with information tied to a potential offense and searches for data that could identify one. The Supreme Court's June 29 decision in Chatrie v. United States held that accessing geofence data is a Fourth Amendment search, but sent the case back without deciding whether the warrant met probable-cause and particularity requirements.

The report says the constitutional status of keyword-search data remained unsettled because no federal appellate court had ruled on whether obtaining it is a search. The report discusses a 2023 letter from then-House Judiciary Committee Chairman Jim Jordan seeking information from the Attorney General about geofence warrants used in January 6 investigations and a 2022 letter from Senator Alex Padilla urging Google to limit the collection and storage of location data in the context of abortion-related investigations.

The Big Picture

Google has described a three-stage process for geofence requests: first providing an anonymized device list, then expanding location information for a smaller group, and finally disclosing account-identifying information for the remaining devices. Google received approximately 9,000 geofence requests in 2019, which accounted for more than 25% of the warrants Google received in the United States by 2021.

Google processes approximately 400 reverse-keyword warrants per year.

The Chatrie majority relied on Carpenter v. United States in comparing Google's Location History data with historical cell-site location information, and separately held that the third-party doctrine did not apply to the Location History data at issue.

Utah requires a search warrant for geofence data and restricts law enforcement use of keyword warrants, Washington restricts private entities from establishing geofences around health-care facilities, and measures concerning geofence or related location-data restrictions were proposed or pending in Vermont, New York, Missouri, Delaware, and California.

The Bottom Line

Courts must determine what safeguards make the collection and review of this information constitutional. In the relevant appellate proceedings, seven judges found a Fourth Amendment search, five said the warrant application lacked probable cause, and two did not reach that issue. Only Judge Roger Gregory would have suppressed the evidence, while the other six judges viewed suppression as unwarranted under the good-faith exception. The district court had found the warrant plainly violated Fourth Amendment rights but denied suppression on the good-faith exception, and separately, the Fourth and Fifth Circuits also declined to suppress evidence on good-faith grounds.

Google announced in 2023 that it would reduce the default retention period for Location History from 18 months to three months and migrate the data from its servers to users' individual devices. The probable-cause and particularity question was remanded to the Fourth Circuit.

Spot something wrong? Report an issue with this article