The New Jersey Supreme Court is considering privacy issues in a case where police used cellphone information to track a burglary suspect without first obtaining a search warrant.

Residents of New Jersey residents have a reasonable expectation that their cellphone data will remain private, argued attorney Alison Perrone on behalf of defendant, Thomas Earls.

"People don't expect when they go to bed at night with their cellphone by their side that the government can convert that device into a tracking device without their knowledge or their consent," she said. Monday.

Deputy Attorney General Brian Uzdavinis says police obtained the cellphone data under an emergency exemption allowing the search because they were concerned about the safety of a girlfriend Earls had threatened. He says they didn't violate Earls' expectation of privacy because the cellphone information could only track his location within a mile.

"The defendant has no reasonable expectation in such generalized location information that would reveal nothing more than his general whereabouts," Uzdavinis argued.

The Electronic Privacy Information Center joined the case on behalf of the defendant. Center attorney Grayson Barber says there must be an appropriate standard for police to get access to cellphone information.

"We're not supposed to have a government of unlimited power," she said. "The Constitution of the United States and the Constitution of the state of New Jersey put parameters around the power of law enforcement to locate us at any moment and the time is now to speak to that."

There's no word on when the justices will issue a ruling.