4
CARPENTER v. UNITED STATES
Opinion of the Court
site data. Hess explained that each time a cell phone taps
into the wireless network, the carrier logs a time-stamped
record of the cell site and particular sector that were used.
With this information, Hess produced maps that placed
Carpenter’s phone near four of the charged robberies. In
the Government’s view, the location records clinched the
case: They confirmed that Carpenter was “right where the
. . . robbery was at the exact time of the robbery.” App.
131 (closing argument). Carpenter was convicted on all
but one of the firearm counts and sentenced to more than
100 years in prison.
The Court of Appeals for the Sixth Circuit affirmed. 819
F. 3d 880 (2016). The court held that Carpenter lacked a
reasonable expectation of privacy in the location information collected by the FBI because he had shared that
information with his wireless carriers. Given that cell
phone users voluntarily convey cell-site data to their
carriers as “a means of establishing communication,” the
court concluded that the resulting business records are not
entitled to Fourth Amendment protection. Id., at 888
(quoting Smith v. Maryland, 442 U. S. 735, 741 (1979)).
We granted certiorari. 582 U. S. ___ (2017).
II
A
The Fourth Amendment protects “[t]he right of the
people to be secure in their persons, houses, papers, and
effects, against unreasonable searches and seizures.” The
“basic purpose of this Amendment,” our cases have recognized, “is to safeguard the privacy and security of individuals against arbitrary invasions by governmental officials.” Camara v. Municipal Court of City and County of
San Francisco, 387 U. S. 523, 528 (1967). The Founding
generation crafted the Fourth Amendment as a “response
to the reviled ‘general warrants’ and ‘writs of assistance’ of
the colonial era, which allowed British officers to rum-