A geofence warrant has to be narrowly tailored for particularity. Here, the government sought identifying information about what cell phones were in a government building. (The building, crime, and date of the occurrence are not disclosed.) In re Info. That Is Stored at the Premises Controlled by Google, 2021 U.S. Dist. LEXIS 110014 (D. Kan. June 4, 2021):
This matter comes before the court on the United States’ Application for a Warrant by Telephone or Other Electronic Means. The government seeks a geofence warrant directed to Google, LLC for location history data covering a defined area that surrounds and includes a building where a federal crime allegedly occurred. Applications for geofence warrants are becoming more commonplace and have drawn scrutiny because of the possibility that they will reveal the identities of potentially numerous individuals who happened to be in the vicinity when a crime was committed but who were not involved in and did not witness the crime. See Geofence Warrants and the Fourth Amendment, 134 Harv. L. Rev. 2508, 2511-12 (2021) (listing examples). “As a result, it is easy for a geofence warrant, if cast too broadly, to cross the threshold into unconstitutionality because of a lack of probable cause and particularity, and overbreadth concerns under Fourth Amendment jurisprudence.” Matter of Search Warrant Application for Geofence Location Data Stored at Google Concerning an Arson Investigation (“Arson”), 497 F. Supp. 3d 345, 353 (N.D. Ill. 2020).
The court issues this written order not only to address the subject application, but also to provide guidance for future search warrant applications involving geofence technology given the relatively sparse authority on this issue. Here, the application and accompanying affidavit are not sufficiently specific or narrowly tailored to establish probable cause or particularity. The court therefore denies the application without prejudice.
Geofence Warrants and the Fourth Amendment, Geofence Warrants and the Fourth Amendment, 134 Harv. L. Rev. 2508 (2021)