United States v. Richard Gratkowski, 964 F.3d 307

Federal agents investigated a child‑pornography website that accepted Bitcoin payments.
Bitcoin transactions are recorded on a public blockchain showing sender and receiver addresses and amounts; addresses are pseudonymous but deanonymizable by analysis.
Agents used a third‑party blockchain‑analysis service to identify a cluster of addresses controlled by the Website.
The government served a grand jury subpoena on Coinbase for account records tied to those addresses; Coinbase identified Gratkowski.
Using that information, agents obtained a search warrant for Gratkowski’s home and seized a hard drive with child pornography; Gratkowski admitted Website use.
Gratkowski moved to suppress, arguing Fourth Amendment privacy rights in blockchain and Coinbase records; the district court denied suppression, he pled guilty conditionally, and appealed.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether individuals have a reasonable expectation of privacy in Bitcoin blockchain records	Carpenter should limit third‑party doctrine; blockchain records reveal transaction histories and can be privacy‑sensitive	Blockchain is public and limited (addresses, amounts); information is voluntarily exposed and like bank/phone records	No reasonable expectation of privacy in blockchain records; third‑party doctrine applies
Whether individuals have a reasonable expectation of privacy in Coinbase account/transaction records	Coinbase records are private customer records and should be protected under Carpenter's reasoning	Coinbase is a regulated financial intermediary like a bank; records are limited and voluntarily conveyed	No reasonable expectation of privacy in Coinbase records; Miller/Smith analogy controls
Whether blockchain analysis or agents' methods violated Fourth Amendment (and whether suppression is warranted)	Sophisticated deanonymization intruded on a protected area and required suppression	No protected privacy interest to intrude upon; alternatively, agents acted in objectively reasonable good faith pre‑Carpenter	No Fourth Amendment intrusion; even if Carpenter applied, good‑faith exception would bar suppression

United States v. Miller, 425 U.S. 435 (1976) (bank records held by third party carry no Fourth Amendment privacy interest)
Smith v. Maryland, 442 U.S. 735 (1979) (third‑party doctrine applied to telephone call logs)
Carpenter v. United States, 138 S. Ct. 2206 (2018) (limited third‑party doctrine for detailed cell‑site location information)
United States v. Jones, 565 U.S. 400 (2012) (reasonable expectation of privacy framework and discussion of search concepts)
United States v. Ganzer, 922 F.3d 579 (5th Cir. 2019) (standard of review for suppression rulings)
United States v. Molina‑Isidoro, 884 F.3d 287 (5th Cir. 2018) (good‑faith exception to suppression)