Obtaining Cell Phone Location Records: SCA, Warrants, Subpoenas

To obtain cell phone location records, law enforcement generally needs a search warrant supported by probable cause served on the wireless carrier, while a private party in a civil case uses a subpoena to the carrier (almost always backed by a court order) with notice to the other parties. Both routes run through the federal Stored Communications Act, 18 U.S.C. §§ 2701–2712, which controls when and how a carrier can hand over customer data.¹

Which track you’re on changes everything about the paperwork, the standard of proof, and how quickly you can move. The sections below walk through each path and the steps that apply to both.

Figure Out Which Type of Location Data You Need

The request you draft depends on what the carrier actually stores and what level of precision your case requires.

Historical Cell Site Location Information (CSLI) is the most common target. Every time a phone sends or receives a call, text, or data signal, the carrier logs which tower handled the connection. Stringing those logs together maps the phone’s rough movements over hours, days, or months. Accuracy depends on tower density: dense urban areas narrow a phone’s position to a small area, while rural CSLI only shows a general vicinity.

Real-time location data shows where a device is right now. Law enforcement can ask a carrier to “ping” a phone for current coordinates, a technique commonly used in missing-person searches and other emergencies.

GPS data, which uses satellite signals to pinpoint a device within a few meters, is usually stored by apps on the phone rather than by the carrier. Getting GPS data often means going to the app developer or the device itself, not the wireless company.

How the Stored Communications Act Governs Access

The SCA draws a sharp line between government requests and everyone else.

For government entities, the statute requires specific legal process before a carrier can be compelled to turn over subscriber records: a search warrant, a court order based on “specific and articulable facts” showing reasonable grounds, or in narrow circumstances an administrative or grand jury subpoena for basic subscriber information like name, address, and payment method.¹

For non-government parties, the SCA is more permissive. It allows carriers to voluntarily disclose non-content records, including location data, to anyone other than a governmental entity.² “Allows” is the operative word. Carriers are permitted but not forced to comply, and in practice most refuse to produce location data on a bare subpoena and insist on a court order to protect themselves from liability.

Law Enforcement: Warrant Supported by Probable Cause

In Carpenter v. United States, the Supreme Court held that the government’s acquisition of historical cell-site records is a search under the Fourth Amendment that generally requires a warrant supported by probable cause.³ That replaced the lower “specific and articulable facts” threshold that police had previously used under the SCA’s court-order provision.

The practical steps:

An officer or agent prepares a sworn affidavit setting out facts that establish probable cause to believe a crime occurred and that the phone’s location records contain evidence of it.⁴
A judge reviews the affidavit and signs the warrant if satisfied.
The warrant is served on the carrier’s legal compliance team, which is then compelled to produce the specified records.

The Court described its ruling as narrow and declined to set a minimum number of days below which no warrant would be needed. It held only that accessing seven days of CSLI (the amount in the case) qualifies as a Fourth Amendment search. Shorter windows remain an open question in the lower courts.³

Carpenter preserved the traditional exigent-circumstances exception. The Court specifically listed pursuing a fleeing suspect, protecting someone facing imminent harm, and preventing the destruction of evidence. Lower courts have applied the exception to bomb threats, active shootings, and child abductions.³

For real-time tracking rather than historical records, the doctrine is less settled, but the majority of federal courts have concluded that probable cause and a warrant are required.⁵

Civil Cases: Subpoena, Notice, and Usually a Court Order

Private parties can’t get a search warrant. In civil litigation, the mechanism is a document subpoena to the carrier.

Under Federal Rule of Civil Procedure 45, a subpoena to produce documents can be issued by the court clerk or by an attorney authorized to practice in the issuing court, and it’s served on the carrier’s legal compliance department or registered agent. Before serving the carrier, the requesting party must provide notice and a copy of the subpoena to every other party in the case so they can object.⁶

Any party, or the carrier itself, can move to quash or modify the subpoena. Common grounds include overbreadth, undue burden, or that the request seeks privileged information. A court must quash a subpoena that fails to allow reasonable time for compliance, exceeds geographic limits, or demands protected material without a valid exception.

Then there’s the practical reality: even a procedurally perfect subpoena usually won’t be enough. Because the SCA gives carriers discretion rather than compelling them to disclose to non-government requesters, most major carriers require a court order directing production before they’ll release location data. Plan on petitioning the court for that order if the carrier pushes back. Carriers also charge compliance fees, ranging from under a hundred dollars for a narrow request to considerably more for extensive data spanning months.

Send a Preservation Letter Immediately

Location data doesn’t exist forever. Retention periods for location-related records vary significantly, running from roughly one year to several years depending on the carrier, with at least one major carrier reportedly retaining records indefinitely. These policies change without notice, and delay works against you.

A preservation letter, sometimes called a litigation hold request, is a written notice to the carrier asking it to preserve specific records tied to a phone number and date range. The letter itself doesn’t compel production, but it puts the carrier on notice that the data is relevant to pending or anticipated litigation and shouldn’t be purged through routine deletion. Send it as early as possible. A perfectly drafted subpoena is worthless if the records are already gone.

For criminal investigations, officers can serve a preservation request under 18 U.S.C. § 2703(f), which requires the carrier to preserve records for 90 days, extendable for another 90 days with a renewed request. That buys time to assemble a warrant application without losing the data.

What to Include in Your Request

Vague or incomplete requests get rejected, delayed, or successfully challenged later. Build in each of the following:

The full name of the account holder and the specific phone number linked to the account.
The correct carrier. Sending a subpoena to the wrong wireless company is a common mistake that costs weeks.
A precise date and time range. Narrow requests fare better; asking for six months of CSLI when the case turns on two specific dates invites a motion to quash for overbreadth.
The type of data: historical CSLI, call detail records, GPS data, or some combination. Each may be stored differently and subject to different retention timelines.
A relevance explanation. In a warrant affidavit this means establishing probable cause; in a civil subpoena it means articulating why the location records bear on the claims or defenses.

Federal court subpoena forms are available from the U.S. Courts website, and state courts provide their own versions through the clerk’s office.⁷

Getting the Records Admitted as Evidence

CSLI arrives as raw data: spreadsheets of tower identifiers, timestamps, and coordinates that mean little on their own. Turning that into a usable exhibit typically calls for an expert witness, often a radio frequency engineer or an analyst trained in cellular network analysis, who can map the towers and plot the phone’s movements. Under Federal Rule of Evidence 702, an expert must be qualified by knowledge, skill, experience, training, or education, and the testimony must rest on sufficient facts, reliable methods, and a proper application of those methods.⁸

The other side will challenge the records on reliability grounds. CSLI shows which tower a phone connected to, not the phone’s exact position, and a single tower’s coverage area can span miles. Network congestion can also push a phone to a tower that isn’t the closest one. Courts have grown skeptical of testimony that presents CSLI as pinpoint location evidence.

Authentication is the other hurdle. The records must come in as genuine business records of the carrier, which usually means obtaining a certification or declaration from the carrier’s custodian of records confirming that the data was generated and maintained in the ordinary course of business. Without that foundation, the records can be excluded as hearsay regardless of what they show.

A Note on Tower Dumps and Geofence Warrants

If what you need isn’t records tied to a known number but rather a list of every phone that was in a certain place at a certain time, you’re outside the ordinary process described above. A tower dump asks a carrier which devices connected to a specific tower during a given window. A geofence warrant asks a technology company to identify every device within a defined geographic boundary during a defined time. Carpenter expressly declined to address tower dumps, and federal courts remain split on whether they require a warrant.⁹ The Supreme Court granted certiorari in Chatrie v. United States in January 2026 to decide for the first time whether geofence warrants comply with the Fourth Amendment.¹⁰ If your case points in that direction, the law is in motion and the answer may look different a year from now.

1
Office of the Law Revision Counsel. 18 USC 2703 – Required Disclosure of Customer Communications or Records
2
Office of the Law Revision Counsel. 18 USC 2702 – Voluntary Disclosure of Customer Communications or Records
3
Supreme Court of the United States. Carpenter v. United States
4
Federal Law Enforcement Training Centers. Affidavit Writing Made Easy
5
Federal Law Enforcement Training Centers. Tracking Individuals via Their Cellular Phones
6
Legal Information Institute. Federal Rules of Civil Procedure Rule 45 – Subpoena
7
United States Courts. Subpoena to Produce Documents, Information, or Objects or to Permit Inspection of Premises in a Civil Action
8
Legal Information Institute. Federal Rules of Evidence Rule 702 – Testimony by Expert Witnesses
9
Congressional Research Service. Geofence and Keyword Searches – Reverse Warrants and the Fourth Amendment
10
Supreme Court of the United States. Chatrie v. United States – Questions Presented