In this photo, taken Oct. 10, 2017, the Supreme Court in Washington is seen at sunset. In a 5-4 decision Friday, The Supreme Court says police generally need a search warrant if they want to track criminal suspects’ movements by collecting information about where they’ve used their cellphones. (Photo by J. SCOTT APPLEWHITE / AP)
WASHINGTON — Police generally need a warrant to look at records that reveal where cellphone users have been, the Supreme Court ruled Friday in a big victory for privacy interests in the digital age.
The justices’ 5-4 decision marks a big change in how police may obtain information that phone companies collect from the ubiquitous cellphone towers that allow people to make and receive calls, and transmit data. The information has become an important tool in criminal investigations.
Chief Justice John Roberts, joined by the court’s four liberals, said cellphone location information “is detailed, encyclopedic and effortlessly compiled.” Roberts wrote that “an individual maintains a legitimate expectation of privacy in the record of his physical movements” as they are captured by cellphone towers.

robot vision