https://www.theverge.com/2017/11/29/16715562/supreme-court-privacy-laws-carpenter-v-united-states

The Supreme Court heard arguments today for Carpenter v. United States, a case that could have serious implications on how police use cellphones to track a person’s location.

Timothy Carpenter was a robbery suspect arrested in connection with a string of armed robberies of RadioShack and T-Mobile stores in Michigan in 2011. After failing to catch Carpenter initially, FBI agents requested cellphone data from wireless carriers, with a court order from a magistrate judge under the Stored Communications Act. FBI agents obtained months of records from cellphone companies and successfully convicted Carpenter in 2013.