Each time a cell phone connects to a cell site, it generates a time-stamped record known as cell-site location information (CSLI). The precision of this information depends on the size of the geographic area covered by the cell site. The greater the concentration of cell sites, the smaller the coverage area. As data usage from cell phones has increased, wireless carriers have installed more cell sites to handle the traffic. That has led to increasingly compact coverage areas, especially in urban areas. Wireless carriers collect and store CSLI for their own business purposes. Police arrested four men suspected of robbing a series of Radio Shack and T-Mobile stores in Detroit. One of the men confessed that, over the previous four months, the group had robbed nine different stores in Michigan and Ohio. The suspect identified 15 accomplices who had participated in the heists and gave the FBI some of their cell phone numbers; the FBI then reviewed his call records to identify additional numbers that he had called around the time of the robberies. P applied for court orders under the Stored Communications Act to obtain cell phone records for Carpenter (D) and several other suspects. That statute permits P to compel the disclosure of certain telecommunications records when it “offers specific and articulable facts showing that there are reasonable grounds to believe” that the records sought “are relevant and material to an ongoing criminal investigation.” P obtained 12,898 location points cataloging D’s movements-an average of 101 data points per day. D was charged with six counts of robbery and an additional six counts of carrying a firearm during a federal crime of violence. D moved to suppress the cell-site data as a violation of his Fourth Amendments rights because they had been obtained without a warrant supported by probable cause. Seven of D’s confederates pegged him as the leader of the operation. The FBI produced maps that placed D’s phone near four of the charged robberies. D was convicted on all but one of the firearm counts and sentenced to more than 100 years in prison. The Court of Appeals for the Sixth Circuit affirmed. It held that D lacked a reasonable expectation of privacy in the location information collected by the FBI because he had shared that information with his wireless carriers. The Supreme Court granted certiorari.