The U.S. Supreme Court limited law enforcement use of “geofence” search warrants in a major legal decision on Monday that is likely to have wide-ranging impacts on privacy rights and law enforcement across the United States.
In a 6-3 decision, the U.S. top court said that “a person has a reasonable expectation of privacy in his or her cell-phone location information.” According to the court, this means that people have a right to privacy when it comes to the location history collected by their phones, as well as the services and apps running on them.
Because of that, the court ruled that authorities are required to obtain search warrants from tech companies like Google for their users’ location data, including requesting historical geofenced location data.
In part, the Supreme Court argued that authorities need to obtain a search warrant to obtain geofenced location data because a user is not willingly sharing their location data using a company’s services like Google. If that were the case, then the “third party doctrine”, which generally says that people have no expectation of privacy when it comes to data they willingly share with others, would apply. For example, in those cases, authorities do not need a search warrant to obtain user data from telecommunications providers.
Geofence warrants allow law enforcement to compel tech companies to hand over information about any of its millions or billions of users in a particular location, based on records of their phone’s location stored in their databases. In practice, police will draw a figure on a map and ask a judge to allow them to demand that tech companies like Google search their vast banks of users’ location data and tell them which of their users were there at the time of questioning.
Critics argued that these often “reverse” search warrants are unconstitutional because they are inherently overbroad and involve data on innocent people.
The court seemed to agree, but did not ban the use of geofence warrants outright, allowing police to limit 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 privacy rights, applies to location data collected by companies like Google from their users’ cellphones. This decision does not prevent law enforcement from obtaining historical cellphone location data, it merely rules that officers are required to obtain a search warrant when requesting geofenced location information, and demonstrate that there is probable cause that the target may have committed a crime.
The decision focuses on a case brought by Chatterjee v. United States, which accused the government of using evidence during a bank robbery trial collected by unconstitutional search warrants. Okello Chatterjee’s lawyers argued that geofence warrants allow investigators to “search first and develop suspicions later” and violate long-standing norms regarding government officials seeking to search or seize data from companies.
Authorities typically have to establish “probable cause” linking a person to a crime to justify a search warrant, while critics argue that geofence warrants do the opposite.
The Supreme Court took up the case after several legal cases involving geofence warrants, including Chatterley’s, left courts across the United States divided, including at the appeals level.
It was not immediately clear what impact the ruling would have on previous court cases. A Justice Department spokesperson did not respond to a request for comment.
The ruling was not expected to change Chatterjee’s sentence in his case because previous courts had ruled that evidence obtained from geofence warrants was collected in good faith. Chattri’s lawyers did not respond to TechCrunch’s request for comment.
The Supreme Court ruled that it was now up to the appeals court to decide whether the search warrant requested in the Chatterjee case showed probable cause and was thus valid.
Some companies that were frequently targeted with requests for location data, such as Google, have begun storing users’ location data on their own devices and not on their servers to prevent users from handing over the data, prompting investigators to reach out to the users themselves. Other companies that store location data, such as Microsoft, Uber, and Yahoo, also receive geofence warrants on a regular basis.
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