# Your Phone Is Not Your Pocket: The Fourth Amendment in the Digital Age
*Two Supreme Court decisions rebuilt search-and-seizure law for a world of smartphones and cloud-held records. Together, Riley and Carpenter explain why the government usually needs a warrant to reach the digital trail you leave behind.*
The Fourth Amendment protects against unreasonable government searches — but its rules were written for physical spaces. In Riley v. California and Carpenter v. United States, the Supreme Court confronted how those rules apply to devices and data that hold "the privacies of life," and in both cases it expanded warrant protection. For contractors that handle government data, build investigative tools, or hold customer records sought by law enforcement, the two cases define the constitutional baseline.
Riley v. California (2014): A Phone Is Different
Police searched the contents of an arrestee's smartphone without a warrant, relying on the long-standing rule that officers may search items on a person incident to arrest. A unanimous Court said no. Chief Justice Roberts wrote that modern cell phones are not just another object in a pocket: they hold immense quantities of personal data — messages, photos, location history, an entire digital life. Searching a phone seized incident to arrest requires a warrant. "Get a warrant," the Court concluded.
Carpenter v. United States (2018): Cracking the Third-Party Doctrine
Carpenter asked whether the government could obtain months of a suspect's historical cell-site location information (CSLI) — records of which towers his phone connected to — from his wireless carrier without a warrant. Under the old third-party doctrine, information voluntarily shared with a third party (here, the phone company) carried no reasonable expectation of privacy. In a 5–4 decision, the Court declined to extend that doctrine to CSLI. Acquiring at least seven days of historical location data is a Fourth Amendment search that generally requires a warrant supported by probable cause. Chief Justice Roberts emphasized that CSLI provides "an all-encompassing record of the holder's whereabouts" and is not meaningfully "voluntary" when carrying a phone is a practical necessity.
Why It Matters for Contractors
- The third-party doctrine is no longer absolute. Carpenter signals that data held by a service provider can still receive constitutional protection. That logic ripples through cloud storage, telematics, biometric, and location-data businesses.
- Digital-evidence and forensics work has constitutional limits. Contractors that support law-enforcement or government investigations need to understand when a warrant is required — an unlawful search can taint a case.
- "We only hold it for them" is not a privacy answer. Holding customer data as a third party does not strip that data of legal protection; it often increases your obligations.
Key Takeaways
- Riley (2014): police generally need a warrant to search a cell phone seized incident to arrest.
- Carpenter (2018): obtaining 7+ days of historical CSLI is a Fourth Amendment search requiring a warrant, narrowing the third-party doctrine.
- Both cases show courts treating digital data as constitutionally distinct from its paper analogues.
Ground the concepts in Cybersecurity 101 and the Glossary entries for third-party doctrine and CSLI.
*Source: Riley v. California, 573 U.S. 373 (2014); Carpenter v. United States, 585 U.S. 296 (2018)*