Yes, police do use GPS to track people, and they do it in more ways than most drivers realize: trackers stuck to vehicles, ankle monitors on people under court supervision, location records pulled from cell phone carriers, and virtual “geofences” drawn around crime scenes. Since 2012, most of this surveillance requires a warrant based on probable cause. A few narrow exceptions apply, and one growing area of the law, geofence warrants, is still being sorted out by the courts.
How Police Actually Use GPS
Not every police use of GPS involves surveilling a suspect. Departments install GPS units in their own patrol cars so dispatchers can send the closest cruiser to a call and supervisors can see where officers are.
Pursuit tools like StarChase let an officer launch a small GPS tag onto a fleeing car from a bumper-mounted launcher. Once the tag sticks, dispatchers track the vehicle remotely and officers can back off the chase.
Courts also order GPS monitoring of people. Judges routinely require defendants on pretrial release, probation, or parole to wear a non-removable ankle monitor that reports location around the clock. This is common in sex offense cases, domestic violence cases, and any situation involving a no-contact order.
The use most people worry about is covert tracking of a suspect’s vehicle. An officer attaches a small device to the underside of a car, and it reports where the car goes and for how long. Investigators use this in drug trafficking cases, cargo theft investigations, and stolen vehicle recoveries. Before 2012, several federal circuits allowed this without a warrant on the theory that driving on public roads carried no privacy interest. The Supreme Court ended that practice.
When Police Need a Warrant to Use GPS
Two Supreme Court decisions set the ground rules.
Vehicle Trackers: United States v. Jones
In United States v. Jones (2012), federal agents attached a GPS tracker to a drug suspect’s Jeep without a valid warrant and monitored his movements for four weeks. The Court held unanimously that installing a GPS device on a vehicle and using it to track someone’s location is a Fourth Amendment search, so officers need a warrant supported by probable cause before placing the device.1Justia. United States v. Jones, 565 U.S. 400 (2012) The majority focused on the physical act: attaching a device to your car is a trespass on your property for the purpose of gathering information, and that intrusion is what the Fourth Amendment was written to prevent.
Cell Phone Location Data: Carpenter v. United States
Six years later, the Court applied the same warrant rule to a tracking method that involves no physical device at all. Every time a cell phone connects to a tower, the carrier logs which tower handled the connection, creating a running record of roughly where the phone has been. In Carpenter v. United States (2018), the Court held that obtaining historical cell-site location information from a wireless carrier is a Fourth Amendment search requiring a warrant.2Justia. Carpenter v. United States, 585 U.S. (2018)
The government had argued that because phone users voluntarily connect to towers, the data belongs to the carrier and police can obtain it without a warrant under the “third-party doctrine.” The Court rejected that argument for cell-site data and specifically held that accessing seven or more days of historical cell-site records qualifies as a search requiring a warrant.3Supreme Court of the United States. Carpenter v. United States, 585 U.S. (2018) – Opinion
Carpenter did not answer every question. The opinion left open tower dumps, real-time tracking, and requests covering fewer than seven days, and it preserved exigent circumstances as a basis for warrantless access.
How Long a GPS Warrant Lasts
Under Federal Rule of Criminal Procedure 41, a tracking-device warrant must specify a reasonable length of time for the device to remain active, and that period cannot exceed 45 days from the date the warrant is issued. Officers must complete installation within 10 days. If the investigation needs more time, a court can grant extensions of up to 45 days each for good cause.4Legal Information Institute. Federal Rules of Criminal Procedure Rule 41 – Search and Seizure Each extension requires a fresh showing to a judge, which provides at least some check against indefinite monitoring.
Exceptions to the Warrant Requirement
A few narrow situations let police use GPS or location tracking without a warrant in hand:
- Exigent circumstances. When someone’s life is in immediate danger, a suspect is about to flee, or evidence is about to be destroyed, officers can act first and seek judicial approval afterward. Probable cause must still exist; the emergency only excuses the delay.
- Consent. If the vehicle owner or phone user consents, no warrant is needed. This comes up when a cooperating witness agrees to carry a tracked device.
- Supervised release. People on probation, parole, or pretrial release can be required to wear a GPS ankle monitor as a condition of release. The court order authorizing the monitoring substitutes for a traditional warrant.
These exceptions are genuinely narrow. Courts scrutinize exigent-circumstances claims closely, and officers who stretch the definition risk having the resulting evidence suppressed.
Geofence Warrants: Still Unsettled
A geofence warrant flips normal surveillance around. Instead of identifying a suspect and then tracking that person, police draw a virtual boundary around a crime scene and ask a tech company to hand over information on every device that was inside that area during a specific window of time. Google has historically been the primary target because of the location data it collects through its mapping and advertising services. In 2023, Google announced it would shorten how long it stores that data and migrate it from its servers to individual devices, a change that could make it effectively impossible for Google to share the data with law enforcement.5Congressional Research Service. Geofence and Keyword Searches – Reverse Warrants and the Fourth Amendment
Federal appeals courts disagree on whether these warrants are constitutional. The Fifth Circuit, in United States v. Smith (2024), held that geofence warrants are unconstitutional general warrants because they force a provider to search its entire database of users to find the few who were near the crime scene.6United States Court of Appeals for the Fifth Circuit. United States v. Smith, No. 23-60321 (2024) The Fourth Circuit declined to extend Carpenter‘s protections to a geofence warrant that sought only two hours of data, finding it far less revealing than weeks of cell-site records.7Congressional Research Service. Geofence Warrants and the Fourth Amendment This split makes the issue a strong candidate for eventual Supreme Court review.
What Happens If Police Track You Without a Warrant
The main remedy is suppression of the evidence. Under the exclusionary rule, a court can throw out anything police obtained through an unconstitutional search, along with anything derived from it. In the Jones case itself, the D.C. Court of Appeals reversed the defendant’s conviction after finding the warrantless GPS tracking violated the Fourth Amendment.8Federal Law Enforcement Training Centers. Case Note – United States v. Jones
There is a significant loophole. The “good faith” exception allows evidence to stand if officers reasonably believed their conduct was lawful at the time. For GPS tracking conducted before Jones was decided in January 2012, courts in circuits that had previously permitted warrantless tracking generally did not suppress the evidence, because officers had been following what was then binding precedent.8Federal Law Enforcement Training Centers. Case Note – United States v. Jones The same pattern has played out with geofence warrants: courts have called them unconstitutional while declining to suppress the evidence because the law was still developing when the warrants were issued.
So a warrant violation does not guarantee a case gets dismissed. It means the tracking evidence, and anything investigators found because of it, can be challenged, and a judge decides whether suppression is appropriate on the specific facts.
A Note on Private Trackers
The rules above govern law enforcement. If you’re worried that an ex, a stalker, or someone else has placed a tracker on your car, that is a different legal question. A growing number of states make it a crime for a private person to place a GPS tracker on someone’s vehicle without consent, with penalties ranging from a misdemeanor carrying up to 90 days in jail to a felony with several years of prison time. These laws most often come up in stalking, domestic violence, and harassment cases. If you find an unfamiliar device on your vehicle, contact local law enforcement.