Deep judicial disagreements over increased police use of GPS surveillance

It overturned a drug-trafficking conviction because the evidence against the defendant included tracking data from a GPS receiver that the police hid under his sport-utility vehicle without a warrant. The device essentially recorded his whereabouts 24 hours a day for four weeks.

Traditionally, courts have held that the Fourth Amendment does not cover the trailing of a suspect because people have no expectation of privacy for actions exposed to public view. The appeals court argued, however, that people expect their overall movements to be private because different strangers see only isolated moments and a police department’s surveillance resources are limited. GPS technology, by allowing police departments to inexpensively track someone’s comings and goings, changes that equation, it said.

Prolonged surveillance reveals types of information not revealed by short-term surveillance, such as what a person does repeatedly, what he does not do, and what he does ensemble,” wrote Judge Douglas Ginsburg.

A person who knows all of another’s travels can deduce whether he is a weekly churchgoer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individual or political groups — and not just one such fact about a person, but all such facts.”

Supreme Court review of the decision seems likely. It contradicted decisions in three similar GPS-related cases by appellate panels in Chicago, St. Louis, and San Francisco.

Not all learned judges agree with Ginsburg’s interpretation. Savage quotes Judge Richard Posner who, in a 2007 decision, argued that “following a car on a public street” is “unequivocally not a search within the meaning” of the Fourth Amendment. While acknowledging that “technological progress poses a threat to privacy by enabling an extent of surveillance that in earlier times would have been prohibitively expensive,” Posner concluded that using a GPS device to investigate a suspect crossed no constitutional line.

The Fourth Amendment “cannot sensibly be read to mean that police shall be no more efficient in the 21st century than they were in the 18th,” he wrote. “There is a trade-off between security and privacy, and often it favors security.”

Posner also cited a 1983 Supreme Court ruling upholding the use of a hidden radio transmitter that helped police trail a suspect. Other judges have argued, though, that the limited power of that device makes it different from the prolonged, automated tracking that GPS devices enable.

Last Thursday, five judges on the San Francisco appeals court dissented from a decision not to rehear a ruling upholding the warrantless use of GPS trackers. Chief Judge Alex Kozinski characterized the tactic as “creepy and un-American” and contended its capabilities handed “the government the power to track the movements of every one of us, every day of our lives.”

Savage writes that several state supreme courts — including those in Massachusetts, New York, Oregon, and Washington — have ruled that their state constitutions require police to obtain a warrant to use them.

The GPS question is likely to make its way to the Supreme Court. Which way will the court lean? “The few Fourth Amendment cases involving contemporary technologies to reach the Supreme Court have generally stuck to the principle that privacy rights cover only actions no one else could normally see or hear,” Savage writes. “In 2001, for example, the court ruled that without a warrant, police cannot point a thermal-imaging device at a home in search of heat associated with marijuana growing.”