How would you feel if the government could freely use satellite technology and computers to secretly turn your property into an invisible surveillance device and track your every public move 24/7? The Obama administration recently told the Supreme Court that it’s perfectly constitutional for the government to do so, without so much as a warrant, probable cause or any basis for suspicion. The future of privacy in the digital age will turn on whether the Supreme Court agrees.


In the case before the court, United States v. Jones, police and FBI agents in Washington, D.C. attached a GPS device to the underside of a suspect’s car and used it to monitor everywhere the car went for a month. That information led to the discovery of cocaine and Antoine Jones’ conviction for drug trafficking. But the U.S. Court of Appeals for the D.C. Circuit reversed the conviction, ruling that the police violated the Fourth Amendment when they monitored Jones’ car without a warrant.


The government argues that this use of a GPS did not infringe privacy because police tracked the car’s movements only in public. The argument relies on two Supreme Court decisions from the 1980s that ruled that using a beeper to assist in tailing a car does not violate privacy as long as it only facilitates the police in observing where the car went in public. As the court explained in Karo v. United States, what a person “knowingly exposes to the public” is not private. But what we “expose to the public” when we go out changes dramatically when a GPS makes it possible, at vanishingly low cost and without human intervention, to follow us everywhere we go for an unlimited period. The Fourth Amendment protects “reasonable expectation of privacy,” and surely people reasonably expect that the pattern of their trips in public over an extended period will remain private.


WHEN DOES THE COLLECTION OF PUBLIC INFORMATION IMPERMISSIBLY INTRUDE ON PERSONAL SECRETS?


So the Court of Appeals for the D.C. Circuit ruled, reasoning that the information police can glean from such monitoring is qualitatively different from what they learn from following a car on a single trip. They might learn, for example, what doctors or psychiatrists you visit, how religious you are, what political meetings you attend, your drinking habits and with whom you associate, whether friend or lover.


Where, however, does the Constitution draw the line between a single trip and a series of trips? When does the collection of public information impermissibly intrude on personal secrets? These are extraordinarily difficult distinctions, and at oral argument the court seemed troubled by how to draw clear and principled lines.


There may, however, be a simpler way to resolve this case, by focusing on the fact that the police attached the GPS to Jones’ car without his knowledge, thereby transforming his property into a secret surveillance device to be used against him. Justices Antonin Scalia and Anthony Kennedy expressed concern about that aspect of the police behavior, and their votes should be sufficient to establish that the Fourth Amendment applies.


Democracy depends on the freedom of citizens to engage with one another in public and private without broadcasting their every association to the government. If the government can hijack our cars, our cellphones, our GPS monitors, our computers and transform them into surveillance against us, what will be left of democratic freedom? As District Court Judge Nicholas Garaufis recently wrote, in a decision requiring the police to get a warrant based on probable cause to obtain access to cellphone location information, “It is time that the courts begin to address whether revolutionary changes in technology require changes to existing Fourth Amendment doctrine.” If we do not adapt laws to technology, privacy may soon go the way of the typewriter. 


DAVID COLE is legal affairs correspondent for The Nation.