Location tracking and phones

The government obtained a warrant to install a GPS device on a vehicle registered to Jones’s wife. The warrant authorized installation in the District of Columbia within 10 days, but agents installed it on the 11th day, in Maryland. The government then tracked the vehicle for 28 days.

The Supreme Court held “that the Government’s installation of a GPS device on a target’s vehicle, and its use of that device to monitor the vehicle’s movements, constitutes a ‘search.’” A vehicle is an “effect” under the Fourth Amendment, and the government “physically occupied private property for the purpose of obtaining information.” The majority said the reasonable expectation of privacy test from Katz v. United States “has been added to, not substituted for, the common-law trespassory test.”

Four Justices concurred in the judgment on a different ground. Justice Alito wrote that “the use of longer term GPS monitoring in investigations of most offenses impinges on expectations of privacy.” The Court did not decide whether the search was reasonable, because the government had not raised that argument below.

Riley, decided with United States v. Wurie, asked whether police may search the data on a phone taken from a person at arrest. The Court held that police generally may not, without a warrant, search digital information on a phone seized from an arrested person. In its words, “a warrant is generally required before such a search, even when a cell phone is seized incident to arrest.”

The Court said modern cell phones hold for many Americans “the privacies of life.” Its answer to what police must do before searching a phone seized incident to arrest was “get a warrant.” Officers may still seize and secure the phone to prevent destruction of evidence while seeking a warrant, and case-specific exceptions such as exigent circumstances remain available.

Prosecutors obtained Carpenter’s cell-site location information from wireless carriers with court orders under the Stored Communications Act, which required only “specific and articulable facts showing that there are reasonable grounds to believe” the records were “relevant and material to an ongoing criminal investigation” (18 U.S.C. 2703(d)). The government obtained 12,898 location points covering 127 days.

The Court held that “the Government’s acquisition of the cell-site records was a search within the meaning of the Fourth Amendment.” It declined to extend the third-party doctrine of Smith v. Maryland and United States v. Miller to these records. It held that a 2703(d) order “is not a permissible mechanism for accessing historical cell-site records,” and that before compelling a carrier to turn them over, the government’s obligation is to “get a warrant.” In a footnote, it said accessing seven days of records is a search, without deciding whether any shorter period is not.

The Court called its decision “a narrow one.” It did not address real-time cell-site data or “tower dumps,” did not call into question conventional surveillance tools such as security cameras, did not address other business records that might incidentally reveal location, and did not consider foreign affairs or national security collection. Exigent circumstances, such as pursuing a fleeing suspect or protecting someone threatened with imminent harm, may still justify a warrantless collection.

• Attaching a tracker to a suspect’s vehicle is a search under Jones. A warrant’s limits on time and place matter: in Jones, agents installed the device outside both.
• A phone seized at arrest can be secured, but searching its data generally needs a warrant under Riley.
• Historical cell-site records generally need a warrant under Carpenter, not a 2703(d) order.
• Where an exigency is relied on, document the facts that made it urgent at the time.
• Carpenter left real-time data and tower dumps open. Follow current guidance from your prosecutor and agency counsel.

The Fourth Amendment restricts the government. In United States v. Jacobsen, 466 U.S. 109 (1984), the Court said it is “wholly inapplicable ‘to a search or seizure, even an unreasonable one, effected by a private individual not acting as an agent of the Government or with the participation or knowledge of any governmental official.’” Jones, Riley, and Carpenter therefore do not directly govern a private investigator working for a private client. An investigator working with or for law enforcement may be treated differently.

Private tracking is governed by state law instead. Ohio is one example. Ohio Revised Code 2903.216, in the version effective October 6, 2026, makes it a crime to knowingly install a tracking device or tracking application on another person’s property without consent, or to cause one to track a person or their property without consent.

The statute exempts a licensed private investigator acting in the normal course of business on behalf of another person only if the owner of the property consents, and only to obtain information about criminal offenses, locate a fugitive from justice, locate lost or stolen property or court-awarded assets, or investigate workers’ compensation claims. The exemption does not apply if the client is the subject of a protection order, or if the investigator knows or reasonably should know the client wants help committing a crime. A violation is a first-degree misdemeanor, or a fourth-degree felony in listed circumstances. See our Ohio tracker page.

• Law enforcement: treat GPS tracking, phone data, and historical cell-site records as warrant matters unless a recognized exception clearly applies.
• Private investigators: check the tracking device law of every state where the device will be placed or used before any tracking work.
• Get the property owner’s consent in writing, and record who consented and when.
• Screen clients for protection orders before tracking work.

• United States v. Jones, 565 U.S. 400 (2012)
• Riley v. California, 573 U.S. 373 (2014)
• Carpenter v. United States, 585 U.S. 296 (2018)
• United States v. Jacobsen, 466 U.S. 109 (1984)
• 18 U.S.C. 2703, Required disclosure of customer communications or records
• Ohio Revised Code 2903.216, Illegal use of a tracking device or application