American citizens should have no expectations of privacy when it comes to location data transmitted by their smartphones.
So the 4th U.S. Circuit Court of Appeals determined in a 12–3 decision at the end of May. The question was whether police can obtain information about where cellphone users are at any given time without getting a warrant. The case revolved around the use of cellphone location data provided by Sprint to track two customers accused of armed robberies in Baltimore.
Under the "third-party doctrine" established by Supreme Court precedents in the 1970s, private data held by third parties—such as phone records—are not subject to the same Fourth Amendment warrant requirements as the records or potential evidence people keep in their own possession. When those precedents were set, phone records merely indicated what number a person called and how long he or she talked. Now they can reveal where people physically are at any given moment.
This was one of several cases attempting to challenge whether the third-party doctrine should still apply in the digital era. Thus far, every court has reaffirmed its status, and it's unclear whether the Supreme Court might reconsider the rule anytime soon.