Orin Kerr writes:
A divided Fourth Circuit has ruled, in United States v. Graham, that “the government conducts a search under the Fourth Amendment when it obtains and inspects a cell phone user’s historical [cell-site location information] for an extended period of time” and that obtaining such records requires a warrant.
The new case creates multiple circuit splits, which may lead to Supreme Court review. Specifically, the decision creates a clear circuit split with the Fifth and Eleventh Circuits on whether acquiring cell-site records is a search.
Read more on The Volokh Conspiracy.