You don’t have to be a suspect. You just have to have been there.

What happened

In Midlothian, Virginia, a bank robber walked in with a gun and walked out with $195,000. Investigators had no suspect. They did have a geographic area and a timeframe. They used a geofence warrant to compel Google to search its location databases and identify every user whose device placed them within the geofence boundary during the robbery window.

The technique worked. A suspect was identified and charged.

The case that resulted, Hankey v. United States, reached the Supreme Court. On April 26, 2026, justices heard oral arguments on whether geofence warrants constitute an unreasonable search under the Fourth Amendment. The decision, expected before the end of June 2026, will determine whether this technique can be used routinely by law enforcement across the United States.

What a geofence warrant actually does

A traditional warrant requires probable cause directed at a specific person or location. An investigator must demonstrate to a judge that a particular individual is likely connected to a crime, or that a particular place likely contains evidence of one.

A geofence warrant inverts this logic entirely.

There is no suspect. There is no specific person being investigated. There is a perimeter drawn on a map. Everyone whose device appears inside that perimeter during the relevant window becomes part of the search. Google receives the warrant, searches its Sensorvault database, and returns a list of anonymous device identifiers. Investigators then narrow the list based on movement patterns, request identifying information for devices of interest, and work backward toward a suspect.

The bank robbery case is one of the cleaner examples because the outcome was a genuine conviction. The constitutional question is not whether it worked. It is whether the mechanism itself, applied to everyone present regardless of suspicion, is consistent with the Fourth Amendment’s protection against unreasonable searches. The EFF has documented dozens of geofence cases where innocent bystanders were flagged, investigated, and in some instances arrested before being cleared.

What Sensorvault actually contains

Google’s Sensorvault is the database at the center of every geofence warrant served on Google. It contains historical location data collected through Google’s Location History feature, which tracks the precise movements of opted-in devices continuously over time.

The database is not a log of occasional location pings. For active users, it contains a continuous record of movement, often granular to within a few meters, updated every few minutes throughout the day. Walking routes, transit patterns, locations visited, time spent at each location.

A geofence warrant served to Google does not retrieve a single location point. It retrieves everything Sensorvault recorded for every device that passed through the defined area during the defined window. This is the same underlying problem that phone carriers selling real-time location data represents at a different layer: once that data exists in a commercial database, the legal threshold for compelling it is the only barrier between it and an investigator.

For a journalist who met a source in a coffee shop near a federal building. For a lawyer who visited a client in a detention facility. For an NGO worker whose daily commute passed near a location that later became the subject of an investigation. For anyone involved in a divorce proceeding whose movements during a specific period are suddenly legally relevant. The question of what Google has stored is not hypothetical.

The problem that has nothing to do with the bank robbery

The Virginia bank robbery is a sympathetic fact pattern for the government. A violent crime. A gun. A significant sum of money. An identified perpetrator brought to justice.

The constitutional question does not stay in that fact pattern.

If the Supreme Court upholds geofence warrants as constitutionally permissible, the technique becomes available for any investigation in any jurisdiction where law enforcement can establish a geographic area and a timeframe. The factual predicate for the geofence does not need to be a bank robbery. It needs to be a crime and a location.

Protests. Demonstrations. Meetings in sensitive locations. Workplaces near incidents that become subjects of investigation. The geofence is drawn around a place. Everyone’s data inside it is compelled regardless of individual suspicion. Knowing how to build a threat model means accounting for the places you have been, not just the communications you have sent.

The Fourth Amendment question is whether “everyone who was here” is a constitutionally sufficient basis for a search of personal location data at scale.

What the outcome means regardless of the ruling

If the Court upholds geofence warrants, the technique becomes settled law and will expand in use.

If the Court strikes them down, the ruling will apply to government-compelled warrants. It will not affect what location data tech companies continue to collect, store, and make available through other legal mechanisms. A ruling in favor of privacy at the warrant level does not erase the underlying data.

Either way, the foundational exposure is the same. Location data that exists in a commercial database can be reached. The legal threshold for reaching it is what the Court is deciding. The data itself is already there.

Turning off Location History on a Google account stops data from entering Sensorvault going forward. It does not delete what is already there unless the user explicitly purges the history. For anyone whose movements over the past several years are stored in that database, the question of what a geofence warrant can compel is not abstract. The same principle applies to understanding what forensic tools can extract from a seized device: the exposure comes from data that was generated, stored, and is now reachable.

The people for whom this is not a theoretical question

For a journalist, the question is what an investigation into a source’s location during a specific event could reveal about a meeting that was never meant to be documented. The recent case of a journalist arrested in Kuwait for reposting a CNN video showed what happens when a journalist’s digital presence in a country is fully traceable. A geofence warrant extends that exposure to anyone who was physically near anything that later became legally relevant, without requiring individual suspicion.

For a lawyer, the question is whether client visits, courthouse appearances, and meeting locations stored in a commercial database can be compelled as part of a broader investigation touching adjacent parties.

For an NGO worker operating in or near sensitive locations, the question is whether historical movement data constitutes a record of associations that can be accessed without individual suspicion.

For anyone who has been near anything that later became the subject of law enforcement attention, the question is whether being in a place at a time is now a sufficient basis for inclusion in a search.

Frequently asked questions

What is a geofence warrant?

A geofence warrant compels a technology company to search its databases for any user whose location data places them within a defined geographic area during a defined time window. Unlike a traditional warrant targeting a specific person or location, a geofence warrant casts a net over everyone present in an area regardless of individual suspicion.

Does this only affect Google users?

Google is the primary target of geofence warrants because of the scale and precision of its Sensorvault database. Apple, Snapchat, and other platforms with location data have also received geofence warrants. The legal question being decided in Hankey v. United States applies to the technique broadly, not only to Google.

Can I protect myself from geofence warrants?

Disabling Location History on your Google account and deleting existing location history removes your data from Sensorvault going forward and retroactively. On an iPhone, disabling location access for individual apps and setting location sharing to “never” or “while using” reduces but does not eliminate location data collection. The most complete protection is not generating the data in the first place.

When will the Court decide?

The Supreme Court heard oral arguments on April 26, 2026. A decision is expected before the end of the Court’s current term, typically late June. The ruling will apply to all federal and state law enforcement use of geofence warrants in the United States.

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The warrant targets a place. Your phone puts you there. That is the entirety of the legal basis for including your data in a criminal investigation. The Court heard arguments on April 26, 2026. A decision is expected before the end of June. What it will settle is whether being in a place at a time is a constitutionally sufficient basis for including your data in a criminal investigation.

There’s no perfect setup. Anyone selling you perfect is selling fear. The goal is simple: make yourself a harder target than the person next to you.