The U.S. Supreme Court for the first time limited police power to track people using GPS devices, ruling in a case that will shape the privacy rights Americans should expect from a new generation of wireless electronics.

Today’s decision addresses the unprecedented power that technology is giving police to peer into Americans’ day-to-day activities. The ruling, which centered on a global-positioning system device officers attached to a drug suspect’s car, may also affect other technologies, including mobile phones.

The decision means that police in many cases will need a warrant to track suspects using GPS, even as the court’s divided reasoning left the exact parameters of that constitutional requirement unclear. The justices unanimously overturned the conviction of Antoine Jones, who owned a nightclub in Washington where prosecutors say he ran a narcotics trafficking organization. They splintered into three camps in their reasoning.