In many ways, privacy has become an archaic concept in the digital age. This week, the U.S. Supreme Court pushed back a little against unwarranted intrusions into private life. But it left for another day the question of how government may use information gathered by digital-surveillance techniques.
The volume of data that is quietly collected about Americans is staggering. Cell-phone companies know when and who you call, and from where. Toll booths record where you drive and how long it takes you to get there.
Grocery stores and other retailers keep records of your purchases to predict your preferences. The Internet tracks the Web sites you visit and how long you spend there, and send you advertisements tailored to your supposed interests.
Security cameras inside and outside banks, convenience stores, subway stations, and other places record the comings and goings of everyone who wanders within view. They lack only coordination to trace the movements of individuals.
But does such routine surveillance alter the traditional American expectation of privacy guaranteed by the 4th Amendment's protection against unreasonable search and seizure? The justices, while unanimous on the case before them, divided on the larger question.
A majority that included Chief Justice John Roberts and Justices Antonin Scalia, Clarence Thomas, Anthony Kennedy, and Sonia Sotomayor concluded that when police attached a global positioning system tracking device to a suspect's vehicle and monitored his movements for 28 days, that constituted an illegal search because it was outside the scope of the warrant that had been issued.
Justice Sotomayor also sided with the reasoning of Justices Samuel Alito, Ruth Bader Ginsberg, Elena Kagan, and Stephen Breyer when she suggested that "it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties."
It needs to be not only reconsidered, but also expanded to protect people from a level of surveillance unimagined outside novels such as George Orwell's 1984. Just because movements, conversations, contacts, and preferences can be tracked without intruding on private property, that does not mean it's right to do so. Justice Scalia conceded as much when he noted that electronic surveillance achieved without trespassing on private property might still be unconstitutional.
The Supreme Court took a first step to safeguard privacy from technological intrusion more than a decade ago, when it said heat-detecting devices could not be used to identify houses in which marijuana was being grown. This week, the justices expanded that concept to include needing a search warrant to attach an electronic device to a suspect's vehicle.
But there is more work to do to make sure that individual liberty does not become an unintended casualty of the information revolution.