United States v. Skinner

Executive Summary

Skinner remains significant—but jurisdiction-specific. Carpenter later protected extended historical CSLI while expressly reserving real-time tracking, and other state and federal courts have reached more protective conclusions.

Key Holdings at a Glance

Cross-Country Drug Courier Investigation

The investigation began after police stopped a participant carrying $362,000 to an Arizona marijuana supplier. Cooperating information and wire interceptions revealed an organization that used couriers to move marijuana from the Southwest to Tennessee and transport proceeds back west.

The supplier purchased pay-as-you-go phones under fictitious subscriber information and issued them to couriers. Agents learned that “Big Foot” would collect approximately 900 pounds of marijuana in Tucson, drive a diesel motorhome, and travel with his son in an F-250 pickup.

Agents initially believed the courier carried the “6447 phone.” A location request showed that phone in Candler, North Carolina, near the organization's leader. Intercepted communications then identified a second number—the “6820 phone”—as the likely courier device.

Continuous pings showed the second phone leaving Tucson, traveling east on Interstate 40, and stopping near Abilene. Agents arrived at a rest stop and found the described vehicles. After Skinner declined consent to search the motorhome, a dog alerted during an exterior sniff. Officers entered and found sixty-one bales containing more than 1,100 pounds of marijuana, two phones, and two semiautomatic handguns.

What Judicial Process Officers Obtained

Agents obtained two orders from a federal magistrate judge. Each authorized the provider to disclose subscriber information, cell-site information, real-time GPS location, and ping data. The first order targeted the number officers initially associated with the courier; the second targeted the corrected number after the first phone's location and intercepted calls clarified which device was traveling.

The majority did not treat the orders as Fourth Amendment warrants and did not rest its holding on probable cause. It concluded no search occurred. Still, the court observed that seeking judicial authorization strengthened the government's position.

GPS, Cell-Site Information, and Pings

The orders and opinion referred to several forms of location information. The provider supplied GPS real-time location, cell-site information, and ping data. Because those methods can differ in precision and device interaction, modern applications should not collapse them into a generic request for “phone records.”

Public-Road Movement Drove the Majority's Analysis

The majority framed the location data as a proxy for Skinner's externally visible movement along public highways. A member of the public could have observed the motorhome traveling through Arizona and Texas and entering a public rest stop.

Agents never established visual surveillance before using the phone location. Skinner argued that the technology supplemented rather than merely augmented human senses because officers did not know his identity, exact vehicle, or route. The majority found those differences immaterial: the constitutional inquiry focused on what Skinner exposed publicly, not what police already knew.

Reliance on United States v. Knotts

In United States v. Knotts, officers used a beeper to help follow a container carried by automobile on public roads. The Supreme Court held that this monitoring was not a search because the vehicle's movements were exposed to anyone who wished to look.

Skinner treated the cellphone signal similarly. Although location technology made surveillance faster and less expensive, the majority concluded that improved police efficiency did not make otherwise public-road observation unconstitutional.

Why United States v. Jones Did Not Control

In Jones, officers physically installed a GPS device on a vehicle and monitored it for twenty-eight days. The Supreme Court's majority held that physically occupying private property to obtain information was a search.

No officer installed anything on Skinner's phone or motorhome. The phone already contained GPS capability when it came into his possession. The Sixth Circuit therefore found no physical trespass and treated Knotts as controlling.

The majority also addressed the separate opinions in Jones, which warned that sufficiently comprehensive tracking can violate reasonable expectations of privacy even without a trespass. It concluded that Skinner's three-day journey did not approach the four-week surveillance in Jones.

Three Days and the Short-Term/Long-Term Line

The majority repeatedly characterized three days as relatively short-term monitoring. It did not announce a numerical ceiling. Instead, it contrasted one cross-country drug run on public roads with persistent surveillance capable of cataloguing a person's life.

Judge Donald's Separate Opinion

Judge Donald concurred in the judgment but rejected the majority's privacy analysis. In her view, obtaining GPS location emitted by a cellphone was a Fourth Amendment search. The fact that a phone was used during criminal activity did not diminish its owner's constitutional protection, and the public-road analogy understated the technology's role in identifying a target officers otherwise could not find.

She would nevertheless have affirmed because investigators possessed probable cause and reasonably relied on detailed judicial orders. The affidavits described months of investigation and would almost certainly have supported warrants had officers used the correct label and procedure.

Skinner After Carpenter

Six years later, Carpenter v. United States held that acquiring the extended historical CSLI at issue was a Fourth Amendment search. But the Supreme Court expressly declined to decide real-time CSLI.

That reservation matters. Carpenter's reasoning concerning involuntary phone location, comprehensive movement records, and technological surveillance creates tension with parts of Skinner, but it did not expressly overrule the Sixth Circuit's real-time-location holding.

Current Sixth Circuit Treatment

In United States v. Perry (2024), the Sixth Circuit relied on Skinner and United States v. Rios to hold that using real-time phone location to find a person moving in public was not a search. That confirms that agencies and courts still encounter Skinner as circuit precedent.

In United States v. Mubarak (2025), a panel declined a request to overrule Skinner or decide whether Carpenter permits revisiting it. The court assumed the four-hour pinging was a search and upheld it because ongoing bomb threats created exigent circumstances.

Practical Guidance for Investigators and Agencies

Real-Time Location Warrant Checklist

1. Identify the number, account, provider, and device identifiers.
2. Provide facts connecting the target to the device.
3. Establish probable cause for the offense and explain why location data will locate the person, evidence, or contraband sought.
4. Describe whether the request seeks GPS, prospective CSLI, provider pings, or another location method.
5. Separate historical records from prospective collection.
6. Specify duration, update frequency, precision, geographic limits, and termination events.
7. Address homes and other protected or sensitive locations.
8. Require records needed to authenticate the method and explain accuracy.
9. Include appropriate minimization, third-party-data handling, return, and audit provisions.
10. Seek additional authorization before materially expanding the surveillance.

Emergency Location Request Checklist

1. Describe the specific threat of death, serious injury, escape, or destruction of critical evidence.
2. Document why delay for ordinary process creates an unacceptable risk.
3. Establish the device's connection to the endangered person or suspect.
4. Request only the precision, frequency, and duration necessary for the emergency.
5. Record when every relevant fact was learned and every request and response occurred.
6. Obtain required supervisory, prosecutorial, statutory, and provider approvals.
7. Preserve the provider's emergency form, communications, returns, and maps.
8. Reevaluate whether the emergency continues after each meaningful location return.
9. Stop when the emergency ends or transition promptly to a warrant.
10. Identify separate authority for entry, stop, arrest, questioning, and evidence searches.

Litigation and Discovery Checklist

1. Identify whether the data were GPS, cell-site, a provider ping, or a hybrid.
2. Determine whether the data preexisted the request or were generated because of government action.
3. Reconstruct exact duration, interval, precision, route, and protected locations revealed.
4. Compare the affidavit, statutory process, order, provider request, return, and actual investigative use.
5. Evaluate device attribution, probable cause, particularity, and any asserted exception.
6. Analyze controlling circuit law and any more protective state constitutional rule.
7. Address Carpenter's effect without claiming it decided real-time CSLI.
8. Trace how location information produced the encounter, dog sniff, entry, arrest, statements, and physical evidence.
9. Analyze good faith separately from whether a search occurred.
10. Preserve raw data, provider certifications, maps, timestamps, communications, and technical testimony.

Frequently Asked Questions

What did United States v. Skinner hold?

The Sixth Circuit held that Skinner lacked a reasonable expectation of privacy in real-time cellphone location data showing his movement on public highways during three days of tracking.

Was this historical CSLI?

No. The provider supplied prospective GPS, cell-site, and ping information used to locate the phone during the drug trip.

Did officers obtain a warrant?

They obtained magistrate orders authorizing location disclosure, but the majority did not treat the orders as warrants or make them necessary to its no-search holding.

Why did the majority rely on Knotts?

It treated the cellphone signal as technological assistance for observing a vehicle's movements on public roads.

How long did the tracking last?

Three days. The court described that period as short term compared with the twenty-eight-day GPS surveillance in Jones.

Did the separate opinion agree that no search occurred?

No. Judge Donald believed the tracking was a search but would have denied suppression because officers had probable cause and reasonably relied on detailed judicial orders.

Did Carpenter overrule Skinner?

Not expressly. Carpenter addressed historical CSLI and reserved real-time CSLI. Later Sixth Circuit opinions have continued to discuss and apply Skinner.

Does Skinner create a nationwide rule?

No. It is Sixth Circuit authority, and other jurisdictions—including state courts applying their own constitutions—may require a warrant.

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Final Assessment

United States v. Skinner is a foundational federal real-time-location case because it treats cellphone tracking as the technological equivalent of following a vehicle exposed on public highways. Its reasoning remains part of Sixth Circuit law, but its boundaries are as important as its holding: public travel, three days, no government-installed device, an identified drug run, and judicial orders supported by detailed affidavits.

The legal landscape is now more complicated than it was in 2012. Carpenter, state constitutional decisions, precise provider pings, and modern aggregation capabilities require investigators to evaluate far more than whether a vehicle happens to be visible in public.