Code of Criminal Procedure · U.S. Supreme Court, 2018

Carpenter v. United States

Carpenter v. United States is a 2018 U.S. Supreme Court decision. This page summarizes key points and works through practice questions for Texas peace officer exam preparation.

Key points

  • Historical CSLI
  • Sufficient duration to provide comprehensive picture
  • Warrant required, with probable cause
  • See also Tex. Code Crim. Proc. art. 18B

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Worked examples

Worked example 1

The cell-site location information (CSLI) of a person's phone collected by a wireless carrier:

  1. Is freely accessible to law enforcement at any time
  2. Generally requires a warrant for historical CSLI of significant duration (Carpenter v. United States), because cumulative location data is protected by a reasonable expectation of privacy Correct
  3. Requires only a subpoena in all cases
  4. Is only accessible to FBI
Why: Carpenter held that government acquisition of historical CSLI is a Fourth Amendment search and generally requires a warrant supported by probable cause. Texas's CCP Art. 18B sets out warrant procedures for electronic communications information.
Statute: Carpenter v. United States, 138 S. Ct. 2206 (2018)