https://www.techdirt.com/articles/20180622/13221840093/supreme-court-says-warrants-are-needed-cell-site-location-info.shtml

The Supreme Court -- in a narrow decision (both in scope and votes) -- has restored a little more of the Fourth Amendment. The long-awaited decision [PDF] in the Carpenter case has been released and the Supreme Court finds, in a 5-4 decision, that cell site location info (CSLI) is technically a third-party record but worthy of the Fourth Amendment's protection.

The defendant challenged the government's warrantless acquisition of 127 days of CSLI, arguing that the constant location records generated (without proactive assistance from phone users) by cell providers raised enough of a privacy issue the Fourth Amendment was implicated. Somewhat surprisingly -- given the long history of expansive readings of the Third Party Doctrine -- the Supreme Court agrees.