Under Carpenter v. United States, decided June 22, 2018, the government generally must get a warrant before compelling a wireless carrier to hand over historical cell-site location information covering an extended period — the Court in that case treated seven days of records as a search requiring probable cause. The 5-4 decision carved the oldest exception into the Fourth Amendment's third-party doctrine: what you voluntarily share with your phone company is not automatically fair game for the police.
USA Daily News 24 is an online publication, not a law firm, and it publishes information, not legal advice. Anyone involved in a criminal case that turns on location evidence should raise these questions with defense counsel, because circuit law varies.
What exactly did Carpenter hold?
Timothy Carpenter was convicted of a string of Detroit-area robberies after the FBI obtained 127 days of his cell-site location records under a court order that did not meet the warrant standard of probable cause. Chief Justice John Roberts, writing for five justices, held that acquiring those records was a Fourth Amendment search. The logic had three parts: cell-site data captures a person's whole catalog of movements, users do not truly volunteer it to carriers, and its comprehensiveness exceeds anything the government could gather by tailing a suspect. A Sixth Circuit panel had upheld the collection under the old standard; the Supreme Court reversed. The Court limited the holding to records spanning at least seven days, left the older third-party precedents — Smith v. Maryland on dialed phone numbers from 1979 and United States v. Miller on bank records from 1976 — formally intact, and did not address real-time tracking or national security requests.
What still does not require a warrant?
The seven-day line leaves a wide gap on the other side of it:
- Shorter historical records. Several courts have found no constitutional problem with tower dumps or CSLI spanning only a few days, and pre-2018 records stored before the decision remain largely outside its reach in some circuits.
- Conventional surveillance. Location data visible to a police officer on the street, and vehicle tracking on public roads, remain governed by pre-Carpenter rules — the Court's 2012 GPS decision, United States v. Jones, required a warrant only for extended physical tracking.
- Voluntary disclosure. Business records like bank statements and dialed numbers remain under the old third-party doctrine, though Carpenter has given lower courts language to question where that line sits.
- Consensual and emergency access. Exigent circumstances and consent carve-outs survive Carpenter untouched, and carriers' voluntary disclosure in emergencies operates under a separate federal framework that the decision did not disturb.
Related stories: Due Process in Immigration Detention: The Time Limits and Safeguards That Apply · Birthright Citizenship: The Litigation Line Running Through the 14th Amendment.
How have lower courts applied it to new technology?
The hardest cases are technologies Carpenter did not name. On geofence warrants — court orders that sweep location data for every phone inside an area during a window, then narrow to suspects — the courts split. A Fifth Circuit panel held in United States v. Smith in August 2024 that geofence searches are categorically unreasonable under the Fourth Amendment and that good faith shielded the officers there. The Fourth Circuit, by contrast, allowed the geofence search in United States v. Chatrie, denying en banc rehearing in July 2024 over sharp dissents. On real-time cell-site data, most courts of appeals have read Carpenter to require a warrant for ongoing tracking, aligning with the Justice Department's own 2018 policy guidance directing federal prosecutors to obtain warrants for such requests. On data brokers who sell commercially aggregated location information, several federal prosecutors' offices and the Federal Trade Commission have warned that purchasing precise location data to evade the warrant requirement raises exactly the concerns Carpenter identified, though no Supreme Court case has resolved that route.
What does the statute require alongside the Constitution?
Independently of the Fourth Amendment, the Stored Communications Act, 18 U.S.C. Section 2703, governs how the government obtains these records. For more than 180 days of stored communications it requires a warrant; for shorter periods it permits a court order on a lesser showing of specific and articulable facts. Post-Carpenter, the constitutional floor has effectively risen to the warrant standard for the long historical location requests that matter most, and several federal courts have held the SCA's lesser standard cannot constitutionally authorize what Carpenter now calls a search.
How far backward and outward does the rule reach?
Retroactivity and source matter as much as duration. The Supreme Court in Carpenter did not say whether the new rule applied to convictions already final, and courts of appeals including the Eleventh Circuit have held it does not benefit defendants whose cases were final before June 2018. The rule's reach across data sources is also unsettled: location records that arrive through a different door — an app's advertising code, a data aggregator reselling carrier-derived or app-derived pings — do not fit neatly inside the holding, which is why FTC warning letters have concentrated on the broker market. A handful of state constitutions go further than the federal floor; the New Jersey and Pennsylvania supreme courts, among others, had already required warrants for cell-site data before the Supreme Court spoke.
What does this change for investigations and for carriers?
As of mid-2026 the operating rule is: extended historical location data needs a warrant everywhere, geofence warrants are on contested footing depending on the circuit, and real-time tracking is treated as warrant territory by the circuits to address it and by federal policy. Carriers have responded with transparency reports and dedicated law enforcement portals that log every request. The deeper shift is doctrinal: Carpenter made the quantity and intimacy of data, not the contract you signed with your carrier, the measure of Fourth Amendment protection. Every new location technology now gets measured against that rule, which is why the seven-day line drawn in 2018 keeps expanding rather than shrinking. The two live questions as of mid-2026 are the same ones Carpenter deferred: whether the aggregation logic follows data bought from brokers, and whether a geofence sweep can ever satisfy probable cause before anyone is identified.