The Court, Privacy, and GPS Tracking

This article is part of a collaboration between the Harvard Political Review and the Harvard College Tech Review to publish exceptional writing at the intersection of politics and technology. Visit the HCTR here.
When technology advances, the law often struggles to keep up.
In 1983, the Supreme Court ruled in U.S. v. Knotts that “A person traveling in an automobile on public thoroughfares has no reasonable expectation of privacy in his movements from one place to another.” The Court decided that police could track an individual by using a “beeper” hidden inside a portable container.
During oral arguments before the Court last week in the case of U.S. v. Jones, Deputy U.S. Solicitor General Michael R. Dreeben reminded the Court of the Knotts precedent. He argued that the 1983 case made the police conduct at issue in Jones legal.
Police, suspecting Antoine Jones of selling cocaine, attached a GPS tracking device to his Jeep Grand Cherokee without a warrant. They monitored his travels for a month, and used the evidence to convict him. But the United States Court of Appeals for the District of Columbia Circuit overturned Jones’s conviction, ruling that the amount of information collected violated the Fourth Amendment.
According to news coverage, most Supreme Court Justices seemed not to be convinced by Dreeben’s application of the Knotts precedent. They raised fundamental questions about the use of standards of “public thoroughfare” and “reasonable expectation of privacy.” The latter test was established by the seminal 1967 case Katz v. U.S., in which the Court held that warrantless electronic eavesdropping of telephone calls made from a public booth violated the Constitution. The “reasonable expectation of privacy” formula has since become the generally applicable standard for determining whether the Constitution affords protection against police searches.
Chief Justice John Roberts spoke up often. “That was 30 years ago,” he said of the Knotts case. “The technology is very different and you get a lot more information from the GPS surveillance than you do from following the beeper.”
Roberts strained to apply earlier precedents to the new technology. “I give you that, that it’s in public. Does the reasonable expectation of privacy trump that fact?…Is it simply the reasonable expectation of privacy regardless of the fact that it takes place in public?” he said, then added later that the police “just sit back in the station and they push a button whenever they want to find out where the car is. They look at data from a month and find out everywhere it’s been in the past month. That seems to me dramatically different.”
The Justices explored examples that suggested they are alarmed by the implications of GPS tracking. Justice Anthony Kennedy wondered whether the FBI could simply put a GPS device on an individual’s overcoat. Roberts asked whether the government could install tracking devices on the cars of the Justices themselves.
Justice Stephen Breyer summed up the defense’s case in an exchange with Dreeben. “If you win this case, then there is nothing to prevent the police or the government from monitoring 24 hours a day the public movements of every citizen of the United States,” he said. “What happened in the past [with traditional surveillance] is memories are fallible, computers aren’t….So, if you win, you suddenly produce what sounds like 1984?”
If the Justices indeed want to find a way to require a warrant for some kinds of GPS tracking, we should cheer them on. The circular “reasonable expectation of privacy” standard provides little protection in an age of constant technological progress. A test based on the amount and kinds of information acquired by police, like the “mosaic theory” applied by the appeals court, would likely stand up better. That court argued that the large amounts of data provided by technologies like GPS trackers reveal unprecedented amounts of information about suspects, creating a “mosaic” out of individual tiles. When it decides Jones next year, the Supreme Court may only make a narrow judgment. But we should hope that in this and future rulings, the Court articulates a sturdier foundation for privacy.