Apart from an occasional rerouting snafu that may leave you stranded in the woods, your handy GPS device prevents you from getting lost and helps other people locate you in case of an emergency.
But what if you don’t want to be found? Could your beloved TomTom or Garmin betray your trust? Using GPS systems and their accompanying smartphone applications too frequently or without understanding certain aspects of the technology can land you in the sights of a stage-5 creeper. Constant access to GPS technology makes it easy for people–from complete strangers to estranged family members to business acquaintances to exes– to hunt you down and follow your movements. Here’s how.
Car Troubles
In the first place, someone could plant a GPS device on your vehicle–under the hood of your car, say–without your even knowing it. That’s exactly what happened to Gayane Indzheyan in 2004: Her ex-boyfriend Ara Gabrielyan pled no contest to one count of stalking and one count of making criminal threats after he planted a GPS device on Indzheyan’s car without her knowledge and then began following her around, repeatedly showing up wherever she happened to be and making menacing comments about what would happen to her if they did not get back together. He served nine months in California state prison before being deported to the Republic of Armenia, according to a Reader’s Digest feature and a report in the Los Angeles Daily News.
Such devices aren’t hard to come by, either. A quick Google search for “GPS spouse tracking” yields several gadgets and methods that can perform this type of dirty work. Some of these devices are so inconspicuous that they are difficult to detect; the GPS Tracking Key, for instance, comes equipped with a powerful magnet so the user can attach it to the bottom of a car in a matter of seconds.
Some private investigators use GPS devices to track people for their clients. The Gomez Detective Agency, made famous through the TV show Cheaters, lists GPS as one of the many surveillance tools it uses to catch people with their pants down. The agency’s investigators follow spouses from place to place and videotape evidence of infidelity, enabling the cheatee to catch the cheater in the act.
Rental car companies can legally track you and impose surcharges for violating their terms of service, as Ron Lee found out after he crossed the Nevada state line in a car that he rented in California. When he returned the car to Pay Less rental car company, the company socked him with a $1400 additional charge. So be sure to read the fine print–or at least ask about jurisdictional or mileage limitations when you get a vehicle.
Next: Smartphone betrayal and revealing applications.
Mobile Spy
Some tracking programs, like the pay-as-you-go AccuTracking software from AccuTracking Inc, can be downloaded to a cell phone. After activating the software, the tracker can determine the location of the phone at any moment by logging in online. The scary thing about AccuTracking is that the person using it can run it in “covert” mode, which renders it undetectable by anyone who doesn’t already know it’s there. AccuTracking forums member hsp2072 voiced his suspicion on the site’s forums, saying that his ex-wife had given him a cell phone as a Father’s Day gift and that he suspected “she had this tracking stuff installed in it before she gave it to me.” Yikes. 
Someone could take a cell phone, install the program, and give it back to the owner without leaving any sign that the software had been downloaded and activated, as London Guardian columnist Dr. Ben Goldacre proved when he tested the software out on his girlfriend’s phone. He had easy online access to her every location, in real time.
The Associated Press reported in April 2009 that James Harrison of Graham, Washington, tracked his wife by using her cell phone’s GPS feature after he suspected her of infidelity. He found her with another man and, in a rage, killed his five children and himself later that night.
Smartphone Maps and Apps
Aside from friend-location software for smartphones, map-based apps can divulge considerably more information than just where you had lunch. Sites like Foursquare, a game in which you log your location to gain rewards from bars, restaurants, and shops that you visit, and Postabon, where you post shopping deals as you see them, have corresponding apps for posting updates on-the-go from your smartphone. 
When you post to these sites, a geotagged map specifies the location of the place you are referencing. A person could easily find you through Foursquare, check which places you’ve logged into, and spot a link to your Facebook and Twitter presences, depending on what your security settings are.
If you use the new Google Buzz service on your smartphone, you’ve probably seen the map that pops up after you buzz. There you are–a bubble-marked dot on a map, surrounded by other dots linked to what other users have buzzed about in your immediate vicinity. So you can see, for instance, that John Doe was at the pizza place across the street, and that Jane Smith was meeting a friend right around the corner. And because Google encourages users to provide their first and last name to boost their public index, a particular person’s footprints are even more noticeable.
Though it offers a legitimate (and cool) way to organize photos and posts, geotagging is also a stalker’s dream function. When you geotag a Tweet, a review, a post, or a photo, metadata logs the exact time when that piece of data was captured and the exact geographical location where it was captured.
A follower with serious boundary issues might plug that information into Google Maps to get a street-view location, so be careful with the data you include with photos that you plan to share online.
Crushing the Teen Dream
GPS tracking is not just for weirdos. Concerned parents may be tempted to enlist the technology to keep track of their children’s whereabouts.
This is fine if the goal is to be able to rescue your child in the unlikely (think odds of getting struck by lightning) event that a stranger kidnaps them–or for that matter, if you warn your child about the tracking setup in advance, and everyone treats it as a safety measure rather than as a spying operation–but what about surreptitiously snooping in on your teen when she gets behind the wheel? A 2006 article in the San Francisco Chronicle reports that Paige White, then 17, was busted by her parents for going to a party after she had told them her destination was a friend’s house. Her parents had installed a CarChip in her car, which logged the routes she drove, her mileage per trip, her driving speed, and her driving tendencies, such as sudden stops and fast turns.
Safety
Under normal circumstances mapping and GPS technologies are safe, fun, and helpful for sharing data, simplifying navigation, and planning meet-ups with friends and family. But if you suspect that you have a stalker on your hands, it’s important to take safety precautions and to notify the authorities about what’s going on.
In the meantime, pay attention to privacy settings in your digital profiles, don’t allow strangers to add you to their Google Latitude list, and watch out for creeps.