Do police need a warrant to track your phone? US court to review access to cellular data

In a new case about digital age technology and privacy, the Supreme Court will consider whether police need warrants to review mobile phone tower records that help them track the location of criminal suspects.

The justices agreed Monday to hear an appeal from Timothy Carpenter, who was sentenced to 116 years in prison after being convicted of armed robberies in Michigan and Ohio.

Police obtained records from cellular service providers that placed Carpenter's cellphone in the vicinity of the robberies.

The question is whether police should have to demonstrate to a judge that they have good reason, or probable cause, to believe Carpenter was involved in the crime. Police obtained the records by meeting a lower standard of proof.

Courts around the country have wrestled with the issue. The most relevant Supreme Court case is nearly 40 years old, before the dawn of the digital age.

The federal appeals court in Cincinnati ruled that police did not need a judge-issued warrant.

Nathan Freed Wessler, the American Civil Liberties Union lawyer who represents Carpenter, said the high court should apply constitutional privacy protections to digital records. "Because cell phone location records can reveal countless private details of our lives, police should only be able to access them by getting a warrant based on probable cause," Wessler said.

The robberies took place at Radio Shack and T-Mobile stores in 2010 and 2011. Carpenter organised most of the robberies, in which he signalled the others in his group to enter the stores with their guns drawn, the government said in its Supreme Court filing. Customers and employees were herded to the back and the robbers filled their bags with new smartphones. They got rid of the guns and sold the phones, the government said.

Police learned of Carpenter's involvement after a confession by another person involved in the holdups. They got an order for mobile phone tower data for Carpenter's phone, which shows which towers a phone has connected with when used in a call. The records help approximate someone's location.

The case will be argued later this year.