Carpenter v. United States, which set the stage for a new standard for privacy in the 21st century, requires the police to obtain a warrant before obtaining cell phone location history from a phone company. Carpenter, along with three other suspects were arrested for involvement with a series of several robberies in 2011. Police used suspects phones to obtain information/data, and track down other potential/suspected accomplices. Carpenter argued that because the collection of data technically fell under the fourth amendment, police were required to obtain some kind of warrant or form of probable cause; however, he claimed that the police only satisfied the "reasonable grounds" standard listed under the SCA.

Because of all of this, Carpenter moved to suppress the cell data, however his movement was denied,

The 6th circuit also denied his movement, claiming that he had no reasonable expectation of privacy on his phone due to the third-party doctrine. Ultimately, despite the fact that Carpenter was still found guilty, the Supreme Court came to the 5-4 decision that acquiring CSLI (Cell Site Location Information) fell under the "reasonable expectation of privacy" doctrine. The court also came to the conclusion that due to the unique and sensitive nature of cell site records, they did not fall under the third-party doctrine. The end result of this case was the decision that cell phone records were to be protected by the Fourth Amendment.