The U.S. Supreme Court on Monday restricted law enforcement's use of “geofencing” search warrants in a major legal decision likely to have far-reaching implications for privacy rights and law enforcement across the United States.
In a 6-3 decision, the U.S. Supreme Court stated that “individuals have a reasonable expectation of privacy in their cell phone location information.” According to the court, this means people have privacy rights regarding the location history collected on their phones and the services and apps running on their phones.
As a result, the court has ruled that authorities must obtain a search warrant when requesting user location data from technology companies such as Google, including requests for historical geofence location data.
The Supreme Court argued that authorities must obtain a search warrant to obtain geofence location data because users do not willingly share their location data just by using the services of companies like Google. If this were the case, the third-party principle would apply, which states that people generally have no expectation of privacy when it comes to data they willingly share with others. In such cases, authorities do not require search guarantees to obtain user data, for example from telecommunications providers.
Geofencing warrants allow law enforcement to force tech companies to hand over information about where their millions or billions of users have been at a particular time, based on the cell phone location records stored in their databases. In effect, police would be asking a judge to draw a shape on a map and require tech companies like Google to search vast amounts of users' location data and tell them which users were there during an interrogation.
Critics argued that these so-called “reverse” search warrants were inherently overreaching and unconstitutional because they included data on innocent people.
The court appears to agree, but stopped short of outright banning the use of geofence warrants, allowing police to narrow their data requests when seeking search warrants.
In other words, the Supreme Court simply ruled that the Fourth Amendment, which protects against unreasonable searches and seizures and effectively protects the right to privacy, also applies to location data collected from users' phones by companies like Google. The decision does not stop law enforcement from obtaining historical cell phone location data; it simply requires authorities to obtain a search warrant and show probable cause that the target may have committed a crime when requesting geofence locations.
The decision centers on the case brought by Chattry v. United States, which accused the government of using evidence during a bank robbery trial that was gathered through an unconstitutional search warrant. Okello Chattry's lawyers argued that geofence warrants allow investigators to “search first and develop suspicions later,” ignoring longstanding norms about how government authorities search and seize data from companies.
While authorities typically need to prove “probable cause” to link a person to a crime to justify a search warrant, critics argue that geofencing warrants work the other way around.
The Supreme Court took up the case after several cases related to geofencing warrants, including the Chhatley case, have divided courts across the country, including at the appellate level.
It is unclear at this point what impact this ruling will have on past court cases. A Justice Department spokeswoman did not respond to a request for comment.
The ruling was not expected to change the sentencing in Mr. Chattry's case, as previous courts have ruled that evidence obtained from geofence warrants was collected in good faith. Chatrie's attorney did not respond to TechCrunch's request for comment.
The Supreme Court held that it was up to the Court of Appeals to determine whether the search warrant requested in Chattry showed probable cause and was therefore valid.
Some companies that have often been targeted for location data requests, such as Google, have begun storing users' location data on their own devices rather than on servers to stop them from handing it over, prompting law enforcement to visit users themselves. Other companies that store location data, including Microsoft, Uber, and Yahoo, also regularly receive geofencing warrants.
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