Police must obtain a warrant before tracking or seizing data from cell phones in the majority of cases, the Supreme Court has announced.
The court said a warrant was also required to retrieve call logs and locations.
The decision officially deems the acquisition of cell phone data a fourth amendment search.
“The fourth amendment protects not only property interests but certain expectations of privacy as well,” the justices wrote in their decision.
“This, when an individual ‘seeks to preserve something as private,’ and his expectation of privacy is ‘one that society is prepared to recognise as reasonable,’ official intrusion into that sphere generally qualifies as a search and requires a warrant supported by probable cause.”
Prior to the court’s ruling, police departments across the country did not require probable cause to seize someone’s phone records from a provider.
Instead, they only needed to convince a judge the material was “relevant and material to an ongoing criminal investigation.”
There are some exceptions, however, since the Supreme Court’s ruling does not apply to cases involving cell phone data and national security or foreign affairs.
The landmark case involved Timothy Carpenter, whose cell phone provider handed records over to local police indicating his location over a 127-day period.
The authorities then used the information as evidence to charge him in multiple armed robberies throughout 2010 and 2011, when he stole cellphones from Radio Shack and T-Mobile.
Mr Carpenter’s lawyers argued the police engaged in “unreasonable search” when they seized his phone records, requesting the information be excluded from his trial in a lower court in 2014.
The judge presiding over the case at the time said he had “no reasonable expectation of privacy in the cell tower data.”
Mr Carpenter was found guilty after a two-week trial in 2014 and sentenced to 116 years in federal prison.
As a result of the Supreme Court’s ruling, his case has been sent back to the lower courts, where other evidence apart from his cell phone records could still prove to incriminate him.
The Supreme Court’s decision is a major victory for personal privacy, and follows similar rulings the justice made on a number of cases over the years.
In 2014, the high court unanimously ruled police are required a warrant to down the content of a person’s smartphone, and overturned the conviction of a drug dealer who was tracked by a GPS police installed on his car in 2012.