US Supreme Court: geofence warrants count as a Fourth Amendment search

The US Supreme Court has ruled that law enforcement's use of broad warrants sweeping up smartphone location data requires privacy protections under the Fourth Amendment, in a decision that backs critics who call the practice an unconstitutional dragnet.

The court decided 6-3 against the government in Chatrie v US, a case widely seen as a test of how privacy rights translate into the digital era. Justice Elena Kagan wrote the majority opinion, holding that the sensitive data collected through “geofence warrants” counts as a Fourth Amendment search and that individuals retain a “reasonable expectation of privacy” even when they may be in a public area.

What the court decided

“An individual has a reasonable expectation of privacy in records about his cell phone's location, and police intrude on that constitutionally protected interest when they demand the information – even though for only a limited time, and from a third-party tech company,” Kagan wrote.

Geofence warrants compel tech companies to hand over location data on people who were at or near a crime scene, defined by the radius of a virtual fence and a particular time window. They are not restricted to precise targets.

The case behind the ruling

The dispute began with local police in Richmond, Virginia, hunting an armed bank robber who fled with $195,000. Investigators used geofence warrants to identify Okello Chatrie, who had opted in to Google's optional location history feature, which recorded his position every few minutes. He pleaded guilty and was sentenced to 12 years in prison.

His lawyers argued the search was overly broad and violated the Fourth Amendment's protection against unreasonable search and seizure. The government countered that accessing only a short slice of location information should not count as a search and therefore should not receive the same protections. The majority rejected that argument, calling the claim that generating location history is a voluntary choice “meritless”.

Why it matters

Justice Sonia Sotomayor wrote that “even short-term monitoring” of a person's movements can reveal “a wealth of detail about his familial, political, professional, religious, and sexual associations”, listing visits to a psychiatrist, an abortion clinic or a criminal defence attorney as examples. Matthew Tokson, a law professor at the University of Utah, warned that without a link to a specific crime, the same technique “could monitor a protest or an abortion clinic or a gun range or a church or an AA meeting or a doctor's office”.

Google has acknowledged in filings that geofence searches “often run a high risk of sweeping in innocent users–sometimes thousands of them”. The court left the question of whether the Chatrie search was itself reasonable to the court of appeals, which must assess whether each step was described with particularity and supported by probable cause. It is the first time since 2018 that the court has examined the Fourth Amendment's scope in this area.