Third-Party Doctrine
Rule
When a person voluntarily conveys information to a third party, they assume the risk that the third party will convey that information to the government. The person thereby loses any Fourth Amendment reasonable expectation of privacy in that information, and the government may obtain it without a warrant.
Elements / Requirements
- The defendant voluntarily conveyed information to a third party
- The third party held the information in the ordinary course of its business
- Because the disclosure was voluntary, no REP survives — government can subpoena or otherwise obtain the records without Fourth Amendment constraint
Exceptions and Limitations
Digital / Comprehensive Data Carve-Out (Carpenter)
The Supreme Court in Carpenter v. United States (2018) held that the third-party doctrine does not apply to cell-site location information (CSLI) spanning seven or more days. The Court reasoned that:
- CSLI is comprehensive, precise, and retrospective — it provides a near-perfect chronicle of a person’s movements
- The disclosure is not truly “voluntary” — modern life compels cell phone use
- The scale and intimacy of the data warrants heightened protection
Carpenter is explicitly narrow: it does not disturb Smith v. Maryland (pen registers) or Miller (bank records) for “conventional” third-party records.
Content vs. Metadata Distinction
Lower courts have sometimes distinguished content (entitled to more protection) from metadata / non-content records (more readily subject to third-party doctrine). Carpenter does not rest on this distinction alone but on the comprehensiveness of the surveillance.
Policy
The doctrine originated in an era of paper records and landline telephones. Critics argue it is poorly suited to the digital age, where individuals necessarily generate voluminous records with service providers as a condition of participating in modern society. Carpenter signals that categorical application of the third-party doctrine to digital records may be unconstitutional when the data is comprehensive enough to reveal intimate details of a person’s life.
Key Cases
- Smith v. Maryland (1979) — no REP in numbers dialed; pen register records voluntarily conveyed to phone company
- United States v. Miller (1976) — no REP in bank records; voluntarily conveyed to bank
- United States v. Carpenter (2018) — CSLI spanning 7+ days requires a warrant; third-party doctrine does not apply to comprehensive digital location records