The GPS as dashboard snitch

In their cocoons of leather upholstery, soothing high-tech sound systems, and automatically activated personal seat settings, drivers have come to regard their car interiors as mobile extensions of the homes that are their private refuges.

The courts have tended to disagree.

Global positioning systems and factory-installed “black box” event data recorders effectively keep late-model vehicles under surveillance 24/7, providing evidence that can place a suspect at a crime scene, undermine an alibi, expose a cheating spouse, or prove liability in an accident.

Although privacy rights advocates warn that the devices augment an already intrusive network of security cameras, speed-monitoring radars, and instantly available databases, police and prosecutors hail the technologies as powerful investigative and forensic tools.

GPS tracking records introduced at trial put a Yolo County, Calif., man at the scene of arson fires, leading to his conviction in October for setting a dozen blazes in 2006.

A Commerce, Calif., man suspected of robbery was tracked by police detectives who planted a GPS unit in his car, mapping his movements and using the evidence to convince a jury he was guilty of assault with a deadly weapon.

In murder cases in Illinois, Washington, and California, the technology has been credited with helping establish guilt.

The evidence is sometimes the product of unwitting self-surveillance. GPS units keep positioning tracks that, if not erased, create a record of a person’s movements.

Event data recorders are standard equipment in most new cars. They record speed, braking, signaling, and other driving behaviors, and can show investigators vital details about what led to a crash.

Wisconsin attorney David A. Schumann, who did some of the earliest legal analysis of GPS potential, points out its usefulness in tracking suspects, locating victims, and monitoring released convicts. “There are cases where people have gotten hung by their own GPS, bought for purposes of evading the law only to have it used against them,” Mr. Schumann says of drug traffickers and migrant smugglers caught with evidence they unknowingly gathered against themselves.

He also recalled the case of a Wisconsin man compelled to plead no contest to felony charges after using a GPS to stalk a former girlfriend.

Corporate owners of car and truck fleets, like rental and delivery companies, legally can track their vehicles and act on employee misconduct detected in the process.

But “tracks of third parties, or of their property, without their knowledge are probably inadmissible and even illegal unless the tracks are conducted by law enforcement,” Schumann says.

Also, in a slap at unauthorized consumer surveillance, state courts in Connecticut and California have struck down rental-car company practices of imposing surcharges based on GPS detection of excessive speeds or prohibited out-of-state travel. California banned such tracking four years ago, but rights advocates remain wary of the expanding surveillance. “We are always concerned about individuals being tracked without their knowledge or informed consent,” says Tori Praul, privacy researcher for the American Civil Liberties Union of Southern California.

Advocates of the new investigative tools claim that the evidence cuts both ways. In a recent trial in Sonoma, Calif., an 18-year-old driver was acquitted of speeding charges after data from his car’s GPS unit refuted police contentions.

As with DNA evidence, lawyers must rely on expert witnesses to interpret for a jury the data provided by GPS or automotive black boxes. Jon Price, a trainer with leading GPS producer Garmin Ltd., has testified in six trials, including two murder cases, in which the tracking information helped win convictions.

“There are limitations to it,” Mr. Price says. “Especially when it comes to some things law enforcement would like to do with it. The GPS position we’re going to calculate for you is only going to be accurate within about 20 to 25 feet. If there is a question about what lane they were in or which side of a divided highway, you can’t really tell.”

In the privacy debate, courts so far have come down on the side of taking advantage of the crime-solving value of the technologies. The 7th US Circuit Court of Appeals issued a landmark ruling last year that GPS tracking of a suspected methamphetamine manufacturer didn’t constitute unreasonable search or seizure as proscribed by the Fourth Amendment.

In “It’s Already Public: Why Federal Officers Should Not Need Warrants to Use GPS Vehicle-Tracking Devices,” attorney John S. Ganz wrote in the Journal of Criminal Law and Criminology three years ago that since 1967, courts consistently have upheld that citizens can’t expect privacy when traveling on public roads.