On Monday, the U.S. Supreme Court imposed restrictions on the use of “geofence” search warrants by law enforcement, marking a significant judicial decision that is anticipated to significantly impact privacy rights and policing across the nation.

In a 6-3 verdict, the highest court in the U.S. asserted that “an individual has a reasonable expectation of privacy in his cell-phone location information.” The ruling indicates that individuals hold privacy rights concerning the location data that their devices collect, along with the applications and services operating on them. 

As a result, the court determined that law enforcement must secure a search warrant when requesting location data from technology firms, like Google, including when seeking historical geofence location information. 

The Supreme Court emphasized that a search warrant is necessary to obtain geofence location data because users do not voluntarily provide their location data to companies like Google merely by using their services. If that were true, the “third-party doctrine,” which posits that individuals have no expectation of privacy regarding information they voluntarily disclose, would apply. In such instances, authorities aren’t required to obtain a search warrant when requesting user data from telecommunications companies, for instance. 

Geofence warrants empower law enforcement to compel tech firms to disclose information about the whereabouts of any of their countless users at a specific time, based on location data logged in the firms’ databases. Typically, officers will outline a region on a map and petition a judge to permit them to require tech companies, such as Google, to comb through their extensive repositories of user location data and identify which users were present during the sought-after time frame.

Critics contended that these often-called “reverse” search warrants are unconstitutional as they are fundamentally overreaching and encompass data from innocent individuals.

The court appeared to concur but refrained from outright prohibiting the use of geofence warrants, instead allowing police to refine their data requests when seeking a search warrant. 

In essence, the Supreme Court asserted that the 4th Amendment, which guards against unreasonable searches and seizures and effectively secures privacy rights, is applicable to location data gathered by companies such as Google from their users’ cellphones. The ruling does not prohibit law enforcement from accessing historical cellphone location data; it merely mandates that agencies acquire a search warrant when asking for geofence location information and demonstrate that there is probable cause that the subject might have perpetrated a crime. 

This ruling revolves around a case brought by Chatrie v. United States, where the defendant alleged that the government utilized evidence obtained through an unconstitutional search warrant during his bank robbery trial. Okello Chatrie’s legal team contended that geofence warrants enable investigators to “search first and develop suspicions later,” thereby undermining established protocols regarding how governmental entities request to search or seize data from companies. 

Typically, authorities must establish “probable cause” linking an individual to a crime to validate a search warrant, whereas opponents argue that geofence warrants operate inversely.

The Supreme Court took up the case following multiple legal disputes regarding geofence warrants, including Chatrie’s, which caused division among courts throughout the U.S., including at the appellate level.

The immediate implications of the ruling on previous court decisions remain unclear. A representative from the Department of Justice did not provide a response to a request for comments.

The ruling is not expected to alter Chatrie’s sentence, as earlier courts determined that the evidence obtained from the geofence warrant was collected in good faith. Chatrie’s lawyers did not reply to a request for comment from TechCrunch.

The Supreme Court determined that it is now up to the Appeals Court to ascertain whether the search warrant sought in the Chatrie case demonstrated probable cause and was therefore legitimate. 

Several companies frequently subjected to location data requests, including Google, have started to retain users’ location information on their devices rather than on their servers to avoid disclosing user data, leading investigators to approach users directly. Other firms storing location data, such as Microsoft, Uber, and Yahoo, also consistently receive geofence warrants.