Citizens of New Jersey can rest a little easier today: The state's Supreme Court, its highest legal authority, has ruled that if the police want to track you via your cellphone, they'll need a warrant to do it.
The ruling yesterday (July 18) came in the case of the State of New Jersey v. Thomas W. Earls. The police found that Earls had stolen and resold a cellphone, which led them to discover that he may have also committed a series of burglaries.
Earls' alleged spoils included expensive items such as golf clubs, TVs, jewelry and sports collectibles.
The police obtained a warrant for Earls' arrest, but were unable to track him down, even after conferring with his girlfriend.
Finally, the police consulted T-Mobile, the wireless carrier Earls used for his cellphone. After two unsuccessful attempts, T-Mobile finally tracked Earls to a motel, where Police arrested the suspect and discovered a cache of stolen goods.
The snag, of course, is that the police did not seek a warrant to track the suspect via T-Mobile — nor did they necessarily need to.
"With increasing accuracy, cellphones can now trace our daily movements and disclose not only where individuals are located at a point in time but also which shops, doctors, religious services, and political events they go to, and with whom they choose to associate," wrote Chief Justice C.J. Rabner in the case's decision.
"Yet people do not buy cellphones to serve as tracking devices or reasonably expect them to be used by the government in that way," he continued. "We therefore find that individuals have a reasonable expectation of privacy in the location of their cellphones under the State Constitution."
The court eventually ruled that individual privacy trumps police suspicion.
"We find that cellphone users have a reasonable expectation of privacy in their cell-phone location information, and that police must obtain a search warrant before accessing that information," the court concluded.
This does not mean that cellphones are completely safe from police surveillance, however.
"To be clear, the police will be able to access cellphone location data with a properly authorized search warrant," Rabner wrote.
In addition, "exigent circumstances," (such as an emergency involving imminent danger) which allow police to investigate certain situations without a warrant, still apply, the judge ruled. [See also: 10 Worst Internet Laws In the World ]
The ruling did not ultimately help Earls, as the court allowed the evidence against him under an "emergency aid" stipulation.
This case is not the first time that unauthorized cellphone access has come up in a ruling. The United States Supreme Court previously ruled that law enforcement requires a warrant to track suspects by planting GPS devices on them or their vehicles.
However, the court narrowly avoided making a comprehensive ruling about cellphone tracking, leaving it up to individual states for the time being.
The issue only became more complicated when a United States Court of Appeals determined that tracking GPS signals from user cellphones was permissible, provided that law enforcement had reasonable suspicions about a person's criminal activity.
The legality of tracking cellphone data without a warrant is by no means decided, especially since federal rulings and state rulings now stand at odds.