ACLU Argues Evidence From Privacy-Invasive Geofence Warrants Should Be Suppressed

WASHINGTON — The American Civil Liberties Union and the ACLU of Virginia, along with eight Federal Public Defender offices, filed an amicus brief on Friday in United States v. Chatrie, the first geofence search case to reach a federal court of appeals. In the brief, the ACLU asserts that police should not be able to exploit the evidence they acquired from a geofence warrant, a novel and invasive surveillance technique that enables law enforcement to search for and locate unknown numbers of people in a large area without reason to believe they were engaged in criminal conduct.

Geofence warrants direct Google to hand over data about every cell phone or other mobile device that Google estimates was in a certain area. These warrants are increasingly common, but they raise serious questions under the Fourth Amendment because they are typically issued without police demonstrating reason to believe all the people who own those devices were involved in any crime.

This appeal comes after a federal judge in Virginia held that the geofence warrant in Mr. Chatrie’s case was overbroad and lacked probable cause for much of the data police obtained. The warrant sought information about all Google device or app users who were estimated to be within a 17.5-acre area surrounding the location of a bank robbery in Virginia.

The court found that the government’s search process left it to the officers and Google, and not to a judge, to decide what location and identifying information the company ultimately revealed, a clear departure from the magistrate’s prescribed role under the Fourth Amendment. However, the court refused to suppress the illegally-obtained evidence on the grounds that the “good-faith exception” to the exclusionary rule — which allows evidence to be admitted when police reasonably rely on a facially valid warrant — applied. ACLU’s amicus challenges this conclusion, arguing that defects in the warrant, including its effect on the privacy of people with no connection to the crime, should have been so obvious that it was not reasonable for police to rely on it.

The brief also highlights the U.S. government’s history of withholding information from judges about the capabilities and impacts of novel surveillance tools, and the importance of suppressing evidence from unconstitutional searches using those tools.

“When seeking warrants, police shouldn’t be allowed to hide the privacy invasiveness of today’s surveillance tools from judges, and then say the evidence they get by using those tools shouldn’t be suppressed because the judge approved them,” said Laura Moraff, Brennan Fellow with ACLU’s Speech, Privacy, and Technology Project.