In another landmark decision on Monday, the Supreme Court ruled that law enforcement agencies must first obtain a warrant before sweeping up smartphone location data from third-party tech companies like Google. In her majority opinion, Justice Elena Kagan wrote that a lower court should reexamine whether the technique known as geofencing constitutes an unreasonable search under the Fourth Amendment. She wrote, “An individual has a reasonable expectation of privacy in records about his cell phone’s location, and police intrude on that constitutionally protected interest when they demand the information.”