By Paul Rosenzweig, The George Washington University Law School
What if your local police department had the technology to individually track and follow you and any of your neighbors as you walked around town? What if advertisers could do the same? You are where you go and, for that purpose, there is a tracking phenomenon known as geolocation. What does this technology mean for a person’s privacy?
Global Positioning System, or GPS
The tracking phenomenon known as geolocation identifies where a person is physically and uses that to derive certain inferences from that information. A GPS works by interacting with satellites that orbit the Earth. It was developed in the 1970s for military use, and was opened for commercial development only in 1995.
It’s the basis for the electronic navigator in your car and on your smartphone. Without it, Uber and Google Maps just wouldn’t work.
Learn more about surveillance and the rule of law.
How GPS Works
Interestingly, the key to geolocation isn’t geography, it’s time. That’s why GPS satellites carry atomic clocks that tell time by measuring the decay of radioactive isotopes. The clocks are synchronized to each other and to clocks on the ground. To the extent that small errors creep into the clocks, they’re corrected every day. And that’s why GPS is based on accurately knowing what time it is.
GPS satellites broadcast their time and their location continuously. A GPS receiver listens for these signals. With the signals from four different satellites, it can calculate exactly where it is and exactly what time it is based on small differences in how long the signal takes to reach the receiver.
The general accuracy of a commercial GPS system falls within about 3 meters, or 10 feet. But, in practice, it can be even more precise since the receiver is continuously calculating its location and averaging the measurements it is making.
This is a transcript from the video series The Surveillance State: Big Data, Freedom, and You. Watch it now, on Wondrium.
Applications of GPS
GPS tracking is used for a wide variety of commercial and military applications. It’s the main way that we navigate. It’s at the heart of futuristic concepts like driverless cars.
And, of course, GPS is the core idea behind precision-guided munitions that hit military targets with great accuracy and specificity. GPS also has surveillance applications.
Learn more about intelligence gathering and criminal investigations.
United States v. Jones
The Supreme Court, in a case captioned United States v. Jones, addressed some of the law and privacy issues of geolocation in a matter involving the decision of FBI agents to put a GPS tracking device on a vehicle belonging to a man named Jones.
Antoine Jones was the operator and owner of a Washington, D.C., nightclub. FBI agents attached a GPS tracker to a Jeep registered in the name of his wife. The vehicle was parked in a public lot at the time.
The authorities suspected Jones was a drug dealer. They tracked him to a location that they came to believe was a drug stash house—that’s a place outside the home where dealers often hide their narcotics. The house was raided, drugs were found, Jones was arrested, and he was convicted.
But the FBI had made a mistake—maybe. They hadn’t gotten a warrant to put the tracker on the car.
The government’s argument was simple. Cars travel on public roads; public roads are in public view; so Jones has no expectation of privacy in his travel and, therefore, no warrant is needed.
But the police lost, and Jones won. The Supreme Court decided the case nine to nothing. Five justices thought that Jones should prevail for a very narrow and limited reason—that the federal agents had trespassed on his property in placing the GPS tracker on his car, and that they were required a warrant to legally do so. Four other justices would have decided the case on a broader ground. They said that the collection of a large volume of data—what is called the big data problem—raises constitutional issues because it allows for the creation of a so-called mosaic picture of Jones.
In other words, by combining many snippets of information, authorities could piece together a much more comprehensive picture of Jones’s life than was revealed by any individual piece. Now, in reality, this picture suggested Jones was a drug dealer, but in other settings, it might have been used to determine whether he was a Democrat, or a Republican, or, any other detail.
Learn more about the problems with privacy.
Insights from the United States v. Jones Case
The Jones case illustrates two points. First, it demonstrates something about the revealing power of geography. Law enforcement authorities concluded that they knew what Jones was because of where he went. That’s very useful analytics, and it’s also very spooky.
Second, we can infer that the mosaic distinction requires some line drawing, but that nobody knows exactly where the line is. How many snippets of information are enough to create a mosaic? Nobody knows, and the majority of the court didn’t answer the question at all.
But we can recognize that the Supreme Court is thinking hard about the Fourth Amendment protections against unreasonable searches and seizures, and applying them in an era of big data where the search might consist of digital scraps of information.
So, as we survey the field of geolocation, there are three separate concepts that form a useful framework for this discussion. They relate, broadly speaking, to the manner in which geolocation information is collected.
First, in some instances, we volunteer that information to the world around us. In others, geolocation data are collateral information that is necessarily collected as part of some other process, like making a phone call. And then third, we can talk about a way of collecting geolocation data through surreptitious means.
Common Questions about Geolocation
A Global Positioning System, or GPS, works by interacting with satellites that orbit the Earth.
The general accuracy of a commercial GPS system falls within about 3 meters, or 10 feet.
Q: What are the three ways in which geolocation information is collected?
First, in some instances, we volunteer that information to the world around us. In others, geolocation data are collateral information that is necessarily collected as part of some other process, like making a phone call. And third is a way of collecting geolocation data through surreptitious means.
