Precedents Cited

The judgment extensively references Carpenter v. United States, a seminal Supreme Court case that scrutinized the government's access to cell-site location information (CSLI) without a warrant. In Carpenter, the Court recognized a reasonable expectation of privacy in CSLI, marking a significant departure from the earlier SMITH v. MARYLAND decision on the third-party doctrine. The court also considered KATZ v. UNITED STATES and Jones v. United States, reinforcing the protection of personal privacy against intrusive searches. Additionally, the Fourth Circuit's decision in United States v. Chatrie was critically examined, with the Fifth Circuit departing from its reasoning in declaring geofence warrants unconstitutional.

Legal Reasoning

The court employed Justice Harlan's two-pronged test from Katz to determine whether a reasonable expectation of privacy exists in the geofence data. First, the appellants demonstrated a subjective expectation of privacy in their Google Location History data. Second, society recognizes this expectation as reasonable, especially given the intrusive nature and comprehensive capabilities of geofence warrants to monitor individuals' movements. Drawing parallels with Carpenter, the court emphasized that unlike CSLI, geofence warrants offer even more granular and pervasive surveillance, capable of tracking individuals into intimate and private settings.

The court was critical of the characterization of geofence warrants by the Fourth Circuit, which viewed them as non-intrusive and insufficiently comprehensive to warrant Fourth Amendment concerns. The Fifth Circuit, however, underscored the inherent invasiveness of geofencing technology, likening it to "modern-day general warrants" that allow arbitrary searches without individualized suspicion. The court argued that the process of issuing a geofence warrant—allowing law enforcement to sift through vast amounts of data without specific target identification—violates the warrant requirement's particularity and probable cause mandates.

Impact

This judgment sets a significant precedent by categorically declaring geofence warrants unconstitutional under the Fourth Amendment. It underscores the judiciary's growing concern over mass data collection technologies and their implications for individual privacy. Future law enforcement practices will likely need to reassess the legality of geofence warrants, potentially leading to stricter oversight and more rigorous standards for obtaining location-based data. Additionally, technology companies may reconsider their data-sharing practices with government agencies to mitigate constitutional challenges.

Geofence Warrants

Geofence warrants are a novel investigative tool used by law enforcement to obtain location data from tech companies like Google. Instead of targeting specific individuals, these warrants define a geographic area and a time frame (the "geofence") to retrieve data on all devices that were present within that region during that period. This method allows authorities to cast a broad net, potentially identifying suspects or witnesses who were in the vicinity of a crime scene.

Fourth Amendment Reasonable Expectation of Privacy

The Fourth Amendment protects individuals from unreasonable searches and seizures by requiring law enforcement to obtain warrants based on probable cause. A "reasonable expectation of privacy" exists if a person has a subjective expectation of privacy that society recognizes as reasonable. In this case, appellants argued that their Google Location History data falls under this protection, as it reveals intimate details about their movements and associations.

Good-Faith Exception

The good-faith exception, established in UNITED STATES v. LEON, allows the admissibility of evidence obtained with a warrant that law enforcement officers believed to be valid, even if the warrant is later found to be defective. In this case, despite the geofence warrant being deemed unconstitutional, the evidence was not suppressed because law enforcement acted in good faith, relying on the warrant's apparent validity during a time when its constitutionality was unclear.