UNITED STATES OF AMERICA v. AARON GRAHAM
US Court of Appeals for the Fourth Circuit, Motz, May 31, 2016,
Cell-Site Data – Third-Party Doctrine- The Fourth Amendment does not protect cellular service provider records of a defendant’s Cell Site Location Information (CSLI) where those records are generated as part of the provider’s ordinary course of business

(Concur- Wilkinson – Congress is in a better position to regulate technological privacy concerns than the courts)
(Dissent – Wynn with Floyd, Thacker- A cell-phone user does not “voluntarily” give location information to the cell-phone company, so there is a reasonable expectation of privacy. This is especially true given the vast amount of data in this particular case.)

Under the “third-party doctrine,” there is no constitutional protection for those who voluntarily relinquish information to a third-party.

Because the user of a cellular phone “voluntarily” gives information regarding their proximity to a tower to a cellular provider in order to get service, they have no reasonable expectation of privacy in that information.

Here the 4th Circuit here adds to similar opinions by:
5th Circuit
6th Circuit
11th Circuit
and somewhat the 3rd Circuit

The Court leaves it to Congress to regulate the manner in which third parties can divulge information to the government and the penalties for failure to abide by these requirements.