The Supreme Court has ruled that police cannot simply collect location data from every phone in an area without following strict rules. Law enforcement agencies that want to use location data to investigate crimes must now obtain a warrant — an official court order with solid justification — just as they would to search a home.

The case, Chatrie v. United States, resolved a legal question that privacy advocates have pursued for years: whether police can use "geofence" warrants, which are requests to technology companies to hand over location data for all devices in a specific geographic area during a specific time period.

How This Works

Imagine police suspect a robbery happened at a shopping mall between 2 p.m. and 3 p.m. on a particular day. They could ask Google — which keeps location history for many Android phone users who have opted in — to provide information about every phone that was inside the mall during that time window.

Google's process involves three steps. First, the company returns a list of anonymous device identifiers for all phones in the area. Second, police can narrow their request to a smaller area or shorter time period. Third, police can ask Google to identify which specific phones belong to which people.

The problem, according to privacy advocates, is the first step. Collecting data on everyone in an area — even people who have nothing to do with the crime — amounts to searching the privacy of innocent bystanders. The Constitution's Fourth Amendment protects people against unreasonable searches.

The Supreme Court's Decision

The Court agreed with those concerns. Police can still use location data to investigate crimes, but they now need to convince a judge that their request is narrowly focused and based on solid evidence that a crime occurred. They cannot simply cast a wide net and sort through all the data afterward.

This is a meaningful limit. A request for all devices in a five-block radius during a two-hour window could capture hundreds of innocent people's location information. Under the new ruling, police would need to explain to a judge why they need data from that specific area for that specific time — based on facts they have already gathered about the crime.

Google has already begun changing how it handles these requests internally, according to the company's own court filing. Other companies that hold location data — phone makers, advertising technology firms, and mobile carriers — now operate under the same legal requirements.

This decision fits a broader pattern. Over the past several decades, courts have gradually been applying privacy protections to digital surveillance tools that did not exist when the Constitution was written. A 2018 Supreme Court ruling required police to get a warrant before accessing historical cell phone location records. Today's decision extends that principle to geofence searches, which affect many people at once rather than just one suspect's records.

It is worth noting that the Court did not eliminate geofence warrants as a tool. Police who have documented probable cause and a narrowly tailored request can still use them. The ruling adds oversight and procedural discipline to a technique that previously operated with minimal judicial review. After years of litigation over this question, there is now a clear constitutional answer.