Technology and the Third-Party Doctrine

Question 1

Carpenter v United States

Answer 1

In 2011, after arresting four men suspected of robbing Radio Shack and T-Mobile stores, law enforcement used one suspect’s information to identify Timothy Carpenter as an accomplice. Without a warrant, they obtained Carpenter’s cell-site location information (CSLI) from his mobile service providers under the Stored Communications Act, which only requires “reasonable grounds” rather than probable cause. This data, comprising 12,898 location points over four months, placed Carpenter near the crime scenes at relevant times. Carpenter was convicted based on this and other evidence. He appealed, arguing that obtaining CSLI without a warrant violated the Fourth Amendment.

Issue
The central issue was whether the government conducts a Fourth Amendment search when it accesses historical cell phone records that reveal the user’s past movements without a warrant.
Holding
The Supreme Court held that accessing CSLI constitutes a search under the Fourth Amendment and generally requires a warrant supported by probable cause.