https://www.cnbc.com/2018/06/22/supreme-court-rules-warrants-required-for-cellphone-location-data.html

The U.S. Supreme Court on Friday imposed limits on the ability of police to obtain cellphone data pinpointing the past location of criminal suspects in a victory for digital privacy advocates and a setback for law enforcement authorities.

In the 5-4 ruling, the court said police generally need a court-approved warrant to get access to the data, setting a higher legal hurdle than previously existed under federal law. The court said obtaining such data without a warrant from wireless carriers, as police routinely do, amounts to an unreasonable search and seizure under the U.S. Constitution's Fourth Amendment.