Suspect spousal infidelity? GPS her!

In a rambling building that overlooks a freeway in San Diego, a bank of computers monitors the travels of trucks carrying hazardous materials, making sure they don't go anywhere near such landmarks as the White House and the capitol building of Arkansas.

Using GPS software, the computers also track cars for seven police agencies. Some of the vehicles are waiting to be stolen, while others are driven by unsuspecting suspects who are under surveillance.

And then there are the private citizens, some 5,000 of them, whose cars are tracked night and day. Finding their latitude and longitude is as easy as logging on to the Internet, typing in a password and looking at a computerized map. It's impossible, however, to find out how many of the customers track their spouses or partners without telling them.

"It does happen," admits John Phillips, president and CEO of Satellite Security Systems, a location-tracking company. "We don't promote it. We hope it's used more for safety for wives and husbands than spying on them."

But the company doesn't ask questions. And its tracking systems are so inexpensive and easily hidden that they may even tempt a suspicious spouse who pinches pennies. It costs just $600 to $700 to outfit a car or truck with a master control device, which is about the size of a compact disc case and an inch thick. It's connected by a wire to a matchbook-size GPS sensor.

While the U.S. Supreme Court has ruled that it's legal for cops to use technology to track a suspect on the road, it's not so clear whether you can monitor your spouse's movements. "As is so often the case, law develops behind new technology," said Mark Grossman, a Miami attorney who specializes in technology law.

Image: Tracking Unit