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Back to Archives | Back to January 2004 Contents 

Chief's Counsel

GPS Tracking Devices and the Constitution

Rob Cerullo

Advanced technology greatly enhances a police officer's ability to fight crime but presents challenging constitutional issues. One particularly helpful new tool is the global positioning system (GPS) tracking device, a computerized unit that police can attach to a suspect's vehicle and then monitor to track the vehicle's movements. The GPS device is similar to a traditional tracking device sometimes called a "bird dog," but GPS provides more precise and detailed information. For example, the GPS unit can be programmed to transmit an electronic signal via a cell tower to a base unit approximately every five seconds. The officer monitoring it can determine the latitude and longitude of the vehicle, tell how long the vehicle remains at its location, view a computer screen containing a map of the area where the vehicle is located, and see where the vehicle is headed—all without leaving police headquarters.

The Big Brother aspect of this technology calls into question its legality. Because this technology is new, there is little case law on it. But two cases in the western United States have affirmed the warrantless use of a GPS tracking device under federal constitutional law based on U.S. Supreme Court precedent concerning bird dog tracking

Bird Dog Cases from the U.S. Supreme Court
In United States v. Knotts the Supreme Court considered in 1983 whether a court order is necessary for the installation and monitoring of a bird dog tracking device in a public location.1 In Knotts law enforcement agents placed the tracking device inside a container of chloroform that they tracked to a methamphetamine lab. The Court ruled that the installation and monitoring of the device in a public place was not a violation of the defendant's rights, because "nothing in the Fourth Amendment prohibited the police from augmenting the sensory faculties bestowed upon them at birth with such enhancement as science and technology afforded them in this case." After Knotts it was clear that law enforcement officers do not need a court order to install or monitor that type of tracking device on a suspect's vehicle as long as it is located in a public place.

But Knotts left open the question of whether the same investigators could lawfully monitor the same device if the vehicle on which it had been installed left the public roadway and entered into private property. The Court addressed that question the following year in United States v. Karo.2 In that case, Drug Enforcement Administration agents obtained a court order for the installation and monitoring of a bird dog tracking device in a 50-gallon drum of ether that they tracked to a residence where they found a cocaine lab. On appeal the defendant claimed that the initial court order was invalid and that the evidence seized inside the residence was the fruit of the illegal monitoring of the device. The Supreme Court ruled that the government did not need a warrant to install and monitor the device initially, but it did need a warrant to continue to monitor the device after it entered a private residence. The Court reasoned that the "indiscriminate monitoring of property that has been withdrawn from public view would present far too serious a threat to privacy interests in the home to escape entirely some sort of Fourth Amendment oversight."

Are GPS Devices Equivalent to Bird Dogs?
Will GPS tracking devices is whether the U.S. Supreme Court will view them as equivalent to the comparatively low-tech bird dog or as an overly intrusive high-tech device that infringes on a defendant's expectation of privacy?

In 1999 the U.S. Court of Appeals for the Ninth Circuit addressed the question in United States v. McIver.3 Because McIver was suspected of cultivating marijuana plants, law enforcement agents placed both a bird dog and a GPS tracking device on his vehicle. After approximately three days, the GPS system malfunctioned and the agents relied solely on the bird dog to track the vehicle to a place where the agents found evidence of marijuana cultivation.

After their convictions, the defendants appealed, claiming that the warrantless installation and monitoring of the tracking devices violated their constitutional rights. Relying on Karo, the court dismissed their challenge, holding that the use of the tracking devices on the vehicle was permissible because the officers did not meaningfully interfere with possessory interests in the vehicle or intrude upon a reasonable expectation of privacy. Two state appeals courts in Washington have also addressed the GPS tracking device issue. In State of Washington v. Jackson law enforcement agents installed a GPS device on the vehicle of a murder suspect.4 After his conviction, the defendant appealed, claiming that the installation and monitoring of the device invaded his right to privacy. In 2002 the appeals courts found that both Knotts and Karo applied to the new GPS technology and that no warrant was necessary because the use of the device "did not impermissibly intrude upon the private affairs" of the defendant. In other words, police violated neither the state constitution nor the U.S. Constitution when they used the device. In 2003 the Washington Supreme Court reviewed the case and held that, due to the more restrictive nature of the state constitution, police in that state must obtain a court order before using a GPS tracking device.5

Kyllo and Police Use of New Technology
In light of the decisions in McIver and Jackson, it would be reasonable to apply to the use of GPS devices the same federal law rules that govern the use of bird dogs. But consideration should include the U.S. Supreme Court's 2001 decision in Kyllo v. United States, because it addresses the use of new and advancing technologies by police.6

In Kyllo law enforcement agents used a thermal imaging device to monitor the heat signature of a house where they suspected marijuana was being grown. The Court ruled that use of the device without a warrant was unreasonable: "When the government uses a device that is not in general public use to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a search and is presumptively unreasonable without a warrant." One could argue that installing and monitoring a GPS tracking device necessitates a court order, because the device "is not in general public use." But because the use of a GPS tracking device in a public area does not intrude upon homeplace privacy, and because it only does better what a traditional bird dog already did, it is likely that the Supreme Court will apply Knotts and Karo. In that event, it would not require a court order for the installation and monitoring of a GPS tracking device as long as the vehicle is and remains in a public area.

Note of Caution
As the Washington Supreme Court's decision requiring a court order for the installation and monitoring of a GPS device makes clear, state law can be more restrictive than federal law. The decision also strongly states legitimate personal privacy concerns in a world of rapidly advancing technology. The U.S. Supreme Court's decision in Kyllo is a harbinger of the same concerns. The courts are not finished with these issues, and the law is evolving. Careful monitoring of legal developments and involvement of legal counsel is recommended.

1 460 U.S. 276 (1983).
2 468 U.S. 705 (1984).
3 186 F.3d 1119 (1999).
4 111 Wash. App. 660 (2002).
5 150 Wn. 2d 251 (2003).
6 533 U.S. 27 (2001).

Editor's note: Rob Cerullo researched and wrote this column; Randy Means reviewed and edited it. Rob, a former narcotics detective with the Chesterfield County Police Department in Chesterfield, Virginia, is a part-time police officer with the department, a full-time law student at the University of Richmond, and a legal intern for his prosecutor's office and for Randy, a career police legal advisor.

This column is prepared monthly by members of IACP’s Legal Officers Section. Interested section members should coordinate their contributions with Randy Means at


From The Police Chief, vol. 71, no. 1, January 2004. Copyright held by the International Association of Chiefs of Police, 515 North Washington Street, Alexandria, VA 22314 USA.

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